User s Manual. Agilent P Series Micro Gas Chromatograph

Transcription

1 User s Manual Agilent P Series Micro Gas Chromatograph

2

3 Agilent G2890/G2891 Micro GC Agilent P Series Micro Gas Chromatograph

4 Agilent Technologies 2000 All Rights Reserved. Reproduction, adaptation, or translation without permission is prohibited, except as allowed under the copyright laws. Part No. G Replaces DOC-2084 First edition, APR 2000 Printed in USA Safety Information The following general safety precautions must be observed during all phases of operation, service, and repair of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of this equipment. Agilent Technologies assumes no liability for the customer s failure to comply `with these requirements. Ground the instrument. To minimize shock hazard, the instrument chassis and cabinet must be connected to an electrical ground. The external power supply provided with this instrument is provided with a three-conductor ac power cable. The power cable can either be plugged into an approved three-contact electrical outlet or used with a three-contact to two-contact adapter with the grounding wire (green) firmly connected to an electrical ground (safety ground) at the power outlet. Do not operate in an explosive atmosphere. Do not operate the instrument in the presence of flammable gases or fumes. Operation of any electrical instrument in such an environment constitutes a definite safety hazard. Keep away from live circuits. Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified maintenance personnel. Do not replace Agilent Technologies, Inc Centerville Road Wilmington, DE USA components with power cable connected. Under certain conditions, dangerous voltages may exist even with the power cable removed. To avoid injuries, always disconnect power and discharge circuits before touching them. Do not service or adjust alone. Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present. Do not substitute parts or modify instrument. Because of the danger of introducing additional hazards, do not install substitute parts or perform any unauthorized modification of the instrument. Return the instrument to Agilent.Technologies. Service for repair to ensure that safety features are maintained. Do not over-pressurize internal gas cylinder. The internal gas cylinder on the Model P200/ P200H must not be pressurized to greater than 1,800 psi (12,410 KPa). Only Agilent Carrier Refill Kit number PNU-2058 can safely be used to recharge the internal gas cylinder. The use of any other tank filling apparatus is dangerous and could result in injury. Additionally, the only approved carrier gases are helium or argon Using any other carrier gas is dangerous and could result in injury. Agilent Technologies also recommends that the internal gas cylinder be hydrostatically checked at least every five years to insure its structural integrity. Only Use Supplied Power Source. All Agilent products require the use of an external power source to either recharge the internal battery or power the instrument. The only approved power supply for all Agilent equipment is the Model PWR-1800 or The use of any other power supply could result in catastrophic failure of either the battery or electrical system leading to personal injury. Therefore only use the recommended power supply. Hot surfaces should be avoided. The P200H and M200H have heated inlets which are maintained at 110 C. Contacting the inlets once they are at operating temperatures can result in injury. Extreme care should be taken to avoid these surfaces. Safety Symbols This manual contains safety information that should be followed by the user to ensure safe operation. WARNING A warning calls attention to a condition or possible situation that could cause injury to the user. CAUTION A caution calls attention to a condition or possible situation that could damage or destroy the product or the user's work. Sound Emission Certification for Federal Republic of Germany. If Test and Measurement Equipment is operated with unscreened cables and/or used for measurements in open set-ups, users have to assure that under these operating conditions the Radio Interference Limits are still met at the border of their premises. The following information is provided to comply with the requirements of the German Sound Emission Directive dated January 18, 1991 Sound pressure Lp < 70 db(a) During normal operation At the operator position According to ISO 7779 (Type Test)

5 Contents Chapter 1 Introduction General description... 2 How to use this manual... 3 Technical specifications... 4 Chapter 2 Basic Theory What is gas chromatography?... 8 What is a gas chromatograph? What is a chromatogram? Parameters affecting a separation Chapter 3 Installation Unpacking Initial installation Carrier gas selection Filling the P200 internal carrier gas cylinder Verifying installation Sample connections Running a sample Chapter 4 Hardware Description Front panel Back panel Right panel Internal components Chapter 5 Columns Introduction Analysis conditions Column conditions Chapter 6 Theory of Operation Electronic block diagram Pneumatic schematics Chapter 7 Troubleshooting Troubleshooting Assembly/ parts replacement i

6 Contents Glossary Appendix A TCD Schematic and Nominal Resistance Values 105 Appendix B Quad-Series Micro Gas Chromatograph 117 Appendix C Precolumn backflush-to-vent and the backflush modules Theory of operation of the precolumn backflush-to-vent Eight steps to backflush method development Connecting a sample to the backflush modules Analytical columns in the backflush modules Sample component identification Example chromatograms from backflush modules Other applications for the BFM Typical BFM operating parameters Benefits of BFMs Troubleshooting ii

7 1 Introduction

8 Introduction General description Welcome to the world of high speed Micro Gas Chromatography. The Agilent P200 and the P200H are completely self-contained, miniaturized gas chromatographs (GCs) designed specifically for fast, accurate analysis. These analyzers are used in combination with the powerful Windows TM based EZChrom 200, the Agilent data handling and instrument control software. The complete package is a comprehensive, easy to use gas analysis system. Today, high-speed gas analysis is possible in the field with the Micro GC. Each GC contains one or two GC modules, an internal carrier gas cylinder and a rechargeable battery pack. The P200 analyzes gases at ambient temperature with boiling points up to 150 C. While the P200H analyzes heated samples (to 110 C) with boiling points up to 220 C, plus samples containing H 2 O vapor. With the P200/ P200H Micro GC, a personal laptop or notebook computer, and the EZChrom 200 data system you can: Analyze gas samples at the source, eliminating sample transfer difficulties and delays. Perform high resolution gas analysis in seconds. Set up, modify, catalog, recall and print instrument settings peak identification tables calibration tables integration parameters. 2

9 Introduction How to use this manual Start and stop the instrument, upload and download experimental conditions and monitor instrument status. Catalog and recall chromatographic data. Integrate and identify observed peaks. Setup and run automated sequences. Perform calibration sequences. Graphically manipulate data displays via zooming functions, scroll bars and cursors. Graphically specify timed integration events. Calculate, display, and print area%, normalization and external standard reports. Generate analysis conditions and sample identification reports for ease in accountability of the data. Store integrated results in a variety of formats for direct input to spreadsheet applications. Main components of the P200/ P200H Using similar technology to that developed for the manufacturing of integrated circuits, components of Micro GCs are fabricated on silicon wafers by batch processing. Silicon batch processing provides repeatable, reliable and inert components with negligible dead volume. The P200/ P200H consists of a micromachined injection system, microbore analytical and reference columns and the micromachined solid state detector (SSD). Combined into a single GC module, these components offer reliability and minimum band broadening essential for high resolution gas analysis. How to use this manual This manual covers the operation of the P200/P200H Micro GC. 3

10 Introduction Technical specifications Chapter 1 describes the principles of gas chromatography and the basic components of a gas chromatograph. Chapter 2 discusses the general installation of the P200/ P200H and the connection of samples. Chapter 3 describes the P200/ P200H hardware front and back panels. This section also focuses on each internal component in detail. Chapter 4 describes the various column options and their applications. Starting conditions are given for each column. Chapter 5 covers the theory of operation and begins with an electronic block diagram description of the P200. It is followed by a description of the pneumatic functions performed by each major subassembly. Chapter 6 focuses on troubleshooting. Chromatographic and hardware symptoms are displayed in troubleshooting tables that lead you to a particular assembly, component or operational problem. A large portion of this section deals with disassembly and assembly of the P200/ P200H. The glossary contains technical terms used in this manual. Quad-Series If you purchased the Quad-Series refer to Appendix B in this book. Technical specifications P200/P200H Carrier gas Externally connectable supply of Helium, Nitrogen, or Argon, 80 psi input. 4

11 Introduction Technical specifications Power P200: Internal 12 volt rechargeable lead-acid battery or 12 VDC power supply, 6 to 8 hours/30 watts maximum P200H:Internal 12 volt rechargeable lead-acid battery or 12 VDC power supply, 4 hours/60 watts maximum Environmental Operating temperature range 0 C to 50 C Humidity range 0 to 95% noncondensing Physical P200: 15 cm (6 inch) high, 36 cm (14 inch) wide, 36 cm (14) deep, 10.4 kg (23 lb) P200H:15 cm (6 inch) high, 36 cm (14 inch) wide, 36 cm (14) deep, 13.2 kg (29 lb) 5

12 Introduction Technical specifications 6

13 2 Basic Theory

14 Basic Theory Read this section if you are new to gas chromatography or if you want to review those principles that affect gas chromatographic separations. If you are familiar with gas chromatography but would like to know more about the theory of operation of your P200, continue to Chapter 6 of this manual. What is gas chromatography? Gas chromatography is an analytical technique used for the separation of the sample components between two phases; a mobile phase (the carrier gas) and a stationary phase (the column packing or coating). The separation begins when a gaseous sample fills the sample loop of the injector. The sample is then injected from the loop onto the column. Carrier gas (mobile phase) transports the sample down the length of the column. Because the different components in a sample have different affinities or solubilities, each component spends different amounts of time in the column packing/coating. When in the packing/coating, a component does not progress down the column. When diffused out of the packing/coating, they progress down the column at the same rate as the carrier gas. As a result, the components spend different amounts of time in the two phases, separating as the carrier gas moves them through the column. Assume that a component takes 5 seconds to travel through an empty column at a constant carrier gas flow rate. Now, fill or coat the tube with stationary phase in which the component is soluble. The same component spends 50% of the time in the stationary phase and 50% in the mobile phase. Therefore, the component elutes in 7.5 seconds rather than 5 seconds. Assume that a second component also emerges in 5 seconds when it travels through an empty column. However, because of its different solubility or affinity, the second component spends 30% of its time in the carrier gas and 70% of the time in the stationary phase. The second component now emerges in 8.5 seconds when it travels through the column. Therefore, the two components separate. 8

15 Basic Theory What is gas chromatography? 10 seconds 20 seconds 30 seconds 40 seconds Column Figure 1 50 seconds Detector Computer A gas chromatography separation Figure 1 is divided into 5, 10 second steps. The first step shows the initial separation of a two component sample (A and B) as it begins in the column. The baseline, representing pure carrier gas, has started to be drawn on the computer screen. The second step shows increasing separation of the two components. The first component (A) begins to pass through the detector. The third step shows the second component continuing to move down the column. The first component (A) has now gone to vent. Finally, the fourth step shows the second component (B) as it begins to pass through the detector. As each component emerges from the column, a peak is drawn on the screen for the detector response versus time plot. In the fifth step the separation is complete and baseline has been reestablished. 9

16 Basic Theory What is a gas chromatograph? What is a gas chromatograph? Now that you know the factors affecting chromatographic separation, it is easy to understand the function of the main components in a Micro Gas Chromatograph. This section discusses the function of the five main components of a Micro GC as seen in Figure 2. Figure 2 Basic GC compounds Carrier gas and gas control The first component of a Micro GC is the carrier gas or mobile phase. The carrier gas is contained in a high pressure cylinder. A two stage regulator is attached to the cylinder to allow monitoring and regulation of pressure. It also enables you to determine when replacement or refilling of the tank is necessary. An on/off valve allows you to open the tank to let the carrier gas flow through the injector, through the column and the detector then out through the instrument vents. The most common carrier gas used is helium. Helium provides the required sensitivity for most GC applications. 10

17 Basic Theory What is a gas chromatograph? The injector The second major component is the injector. The injector introduces a measured amount of sample into the inlet of the analytical column. The Micro GC contains a timed injector micromachined from a silicon wafer using manufacturing techniques borrowed from the semiconductor industry. The injection sequence begins when the carrier gas for the reference column flows through the injector. Two flow restriction channels moderate the flow of carrier gas to both the reference and analytical columns. To take a sample, the sample microvalve in the injector opens allowing the internal vacuum pump to pull sample gas through the sample loop and out the vent. The sample microvalve then closes, the vacuum pump turns off and a switch valve connects to the outlet of the pressure regulator, thereby pressurizing the sample loop. Because of the flow restriction channels, the pressure in the sample loop is slightly higher than the pressure at the inlet of the analytical column. Therefore, when the inject microvalve opens, the sample from the loop flows into the channel leading to the analytical column. The amount of sample injected depends on the length of time the inject microvalve is open. After a user defined time (typically about 40 msec), the inject valve is closed and the switch valve connects to the vacuum pump. The injected sample flows into the analytical column, where the sample is separated into its components. The separation system The third component and the separation system is the column. The column tubing is packed/coated with a chemical substance that attracts some of the sample components more than others. As a result, components will separate as they pass through the column. A wide selection of columns offer a wide selection of selectivity. Although column length as well as tubing dimensions influence separation, separation is primarily influenced by solubility. Because solubility is affected by temperature, column temperature must be controlled. 11

18 Basic Theory What is a gas chromatograph? Reference flow R1 S1 S1 R1 Sample flow Signal Supply voltage Figure 3 Thermal conductivity circuitry Detection system The fourth Micro GC component is a detector. A detector monitors the carrier gas and senses a change in its composition when a component in the sample elutes from the column. One of the most common, reliable and easy to use detectors is the universal micromachined Solid State Detector (SSD). The SSD is a micromachined version of the Thermal Conductivity Detector (TCD). The design of this detector is derived from a Wheatstone Bridge which is an electronic device that compares the electrical resistance of two branches in a circuit. In an SSD, pure carrier gas elutes from the analytical column and passes over two matched filaments (S1, Figure 3). The bridge compares their resistance against those of the reference side (R1, Figure 3). When both sides have pure carrier gas flowing over the filaments, the bridge is balanced and the output is zeroed. When a component elutes, the thermal conductivity on the sample side of the bridge changes. Therefore, the resistance of the analytical side changes and the output indicates a peak is eluting. A regulated power supply controls the voltage being fed to the filaments at a constant level. The bridge also has a balance control and an autozero circuit to zero the detector output between runs. The user can select high, medium or low sensitivity levels which changes the gain level of the electronics. This is unlike 12

19 Basic Theory What is a gas chromatograph? standard TCDs where sensitivity increases by increasing filament temperature and corresponds with a decrease in detector life. Data system The final or fifth component of a Micro GC is the data system. The main purpose of a gas chromatographic system is to generate both qualitative and quantitative data. Data systems provide both a visual recording of the detector output and an area count of the detector response. The detector response is used to identify the sample composition and measure the amount of each component by comparing the area counts of the sample to the analysis of a known calibration standard. Computer based data systems can communicate with the analyzers. This added versatility allows the analyst to store and set operating conditions for an analysis in the computer, making the data system and the analyzer an integrated instrument Peak identification: 1. Oxygen/nitrogen 2. Methane ppm 3. Carbon dioxide ppm 4. Ethane ppm 5. Acetylene ppm Figure 4 Time (seconds) The chromatogram 30 13

20 Basic Theory What is a chromatogram? What is a chromatogram? A chromatogram is a plot of the detector response versus time (Figure 4). The plot begins as you place the sample into the carrier gas stream and should continue until the last component in the sample elutes. The chromatogram depicts each component as it exits the column as a peak. It also shows the separation achieved for that particular sample. Each peak is identified by its retention time and the length of time that a component takes to travel through the column. If analysis conditions (flow and temperature) are maintained constant, the chromatographic trace is very reproducible and could be used for both qualitative and quantitative analysis. Qualitative analysis Qualitative analysis is designed to identify the components of a sample. Gas chromatography is not an absolute qualitative tool and usually must rely on other techniques for peak identification. However, a Micro GC containing two GC modules can seperate the components of a sample with two different stationary phases, simultaneously. The result is peak identifiction and confirmation in a single analysis. To analyze qualitatively, a calibration standard of known composition must be analyzed first. Pure compounds elute at the same time under exactly the same analytical conditions. If you match the calibration standard peaks with those in your samples, you can be fairly sure that you have those compounds in your sample. Quantitative analysis Quantitative analysis is designed to determine the amount or proportions of the components of a sample based on the detector response. The detector response (area or height) is proportional to the amount of a component in a sample. However this response varies slightly with each component. Therefore, it is necessary to experimentally determine the area (or height) concentration relationship by running a calibration standard containing the components of 14

21 Basic Theory Parameters affecting a separation interest. The conditions in which the detector response for the calibration standard must be the same as those in the unknown samples. Table 1 Typical Conditions for the Analysis of C1-C2 Hyrocarbons Column 2 m mm id, 10 um df, PoraPLOTQ Column head pressure 20.5 psi Carrier gas Helium Column temperature 40 C Detector sensitivity HIGH Sample time 10 seconds Injection time 40 milliseconds Run time 32 milliseconds Parameters affecting a separation In order to repeat an analysis or to compare it with standards, the parameters that affect the separation and the general appearance of the chromatogram must be held constant. For example, the chromatogram shown in Figure 4 was obtained under the conditions given in Table 1. Because solubility is a primary factor in the chromatography separation mechanism, temperature controls the rate at which a component elutes from a column. Higher temperatures will accelerate the elution of a compound by decreasing solubility. Temperature control and stability are necessary to duplicate a separation. Temperature limits are dictated by the hardware and the column type. Column head pressure determines the velocity of the mobile phase as it progresses through the column. The velocity of the mobile phase affects how fast a component travels through a column. Setting and maintaining the column head pressure, along with column temperature, controls the elution time of a peak from a column. 15

22 Basic Theory Parameters affecting a separation Two columns with exactly the same stationary phase will behave differently if one is twice as long as the other. Column head pressure will need to be higher for the longer columns. The more narrow and long a column, the higher the head pressure needs to be to achieve the same flow rate. The analyst should consider column dimension factors when trying to duplicate analysis in two different columns. The packing or coating material also affects separation. In GLC, the variety of coatings applied to the solid support or column wall offer an assortment of separation mechanisms that a chromatographer exploits to achieve the best separation possible for its particular application. Agilent Technologies offers an assortment of column types in different dimensions, each of which are recommended for a particular gas analysis application. Chapter 5 discusses columns and their applications. 16

23 3 Installation

24 Installation Chapter 3 describes how to prepare your P200/ P200H for operation. It also includes how to make connections to a computer and how to verify proper installation. Unpacking Your P200/P200H GC is shipped in one container. Other cartons may be included with the shipment if additional accessories or spares have been ordered. Inspect the shipping container for damage. If the container or packing material appear damaged, notify the carrier as well as Agilent Technologies. Keep all shipping materials for the carrier s inspection. Compare the contents of your shipment versus the packing list and your purchase order. If there is mechanical damage or if the instrument does not pass the performance test outlined in the installation instructions, notify Agilent Technologies or your sales representative immediately. The shipping container and the packing are designed to protect your instrument during shipment. Keep the packaging in a safe place for future shipping needs. Initial installation To install and checkout your instrument, place your P200/ P200H in a location near an electrical outlet. Make sure you can easily access both the front and back panels of the instrument. To begin: Caution Do not power your P200 yet! The P200 should not be powered on until the carrier gas is flowing through the detector. 18

25 Installation Initial installation Serial port Power 12 VDC ANALOG/CONTROL SERIAL I/O AUX 12VDC IN A & B RS-232 POWER 12VDC CARRIER FILL 1800 PSI MAX COL A VENT SAMPLE VENT COL B VENT CARRIER OUT REF A VENT CARRIER IN REF B VENT COLUMN A PRESSURE COLUMN B PRESSURE H Sample & column vents Figure 5 P200/ P200H back panel 1. Plug the battery charger into the electrical outlet and then into the P200/ P200H back panel at the location marked Power 12VDC. When the P200/ P200H power is off, the battery charger will replenish power to the internal battery. A minimum charge time of 14 hours is recommended. The battery charger has a trickle charging circuitry to prevent overcharging. The charger can be left on indefinitely without harming the battery. When operating the P200/ P200H, the instrument can run from the internal battery or from the charger. The P200 battery provides 8 hours of power when running with moderate chromatographic conditions. The P200H battery provides 4 hours of power when running with moderate conditions. When operating at high temperatures, as when "baking out" or "column conditioning", run the GC from the charger to avoid running out of power. When a battery is less than 20% charged, it should be recharged. The LED on the front panel power switch of the P200/ P200H begins to flash when the battery is about 80% discharged. The battery status (% Battery) also displays the charge % in the EZChrom 200 Instrument Status window. 19

26 GAS SAMPLE ONL CAUTION: SAMPLE INLET(S) HOT Installation Carrier gas selection Caution To protect the battery from permanent damage, the P200/ P200H will automatically disconnect the load from the battery when it reaches approximately 10.4 Volts. At this point, the green light stops flashing and turns off. If the battery is allowed to discharge to this level repeatedly, the life of the P200/ P200H battery will be dramatically shortened. 2. Connectthe RS-232 cable to the P200/ P200H serial port and to the serial port of your computer. Consult the software manual to choose the communicating COM port. 3. At the front panel of your P200/ P200H, turn the carrier gas on by turning the knob straight up (Figure 6). Carrier on/off ON H OFF GAS SAMPLE ONLY CAUTION: SAMPLE INLET(S) HOT CARRIER CARRIER POWER SERIAL P Series Power on/off Figure 6 P200H front panel 4. At the front panel of the P200, turn on the instrument by pressing the power button. A green light should appear on the button. Carrier gas selection The P200 carrier gas moves the sample through the column. The carrier gas should be dry and of high purity. The thermal conductivity of your carrier gas should differ from components you want to analyze. Because of its high thermal 20

27 Installation Carrier gas selection conductivity, the best choice for most applications is helium. Choose a gas with a purity of at least %. When analyzing low ppm of oxygen and nitrogen, the helium should be at least % pure. If you are analyzing helium or hydrogen in a sample, nitrogen or argon are good carrier gas selections. Caution Your P200/ P200H is configured at the factory to use helium/ hydrogen or nitrogen/ argon as the carrier gas. Use of another carrier gas generates filament temperatures that are too high and that result in damage to the detector if run at the standard voltage levels. The GC controller board will adjust the filament voltage when using argon or nitrogen so that filament temperatures are comparable to those when using helium. These adjustments are discussed in Chapter 6 Theory of Operation. Caution Agilent Technologies does not recommend using hydrogen in the internal tank of the P200. The use of a carrier gas other than helium or hydrogen pose problems that result in a loss in sensitivity. This is caused by the following: a. The reduced voltage results in approximately an eight fold reduction in sensitivity. b. The similarity in thermal conductivity between the carrier and the component being analyzed reduces the detector signal. c. The physical characteristics of the carrier (viscosity, etc.,) results in a loss of column efficiency. In addition, you may see negative peaks due to sample components with higher thermal conductivities than the carrier gas. While the data system provides the Invert Timed Event function, you may also use an invert circuit plug that converts the analog signal for negative peaks to positive and vice versa. Both the voltage adjustments and the installation of the detector invert circuit are discussed in Chapter 5. 21

28 Installation Filling the P200 internal carrier gas cylinder Filling the P200 internal carrier gas cylinder Your P200 Portable Gas Chromatograph contains a refillable, high pressure carrier gas supply cylinder. The cylinder volume is 300 ml and will last 35 to 40hours under normal operating pressure. This cylinder has been certified by the U. S. Department of Transportation (DOT) to a pressure of 1800 psig (12,405 KPa). Periodically, you will need to refill this cylinder. Observe the schematic of the carrier gas refiller apparatus (Figure 7). WARNING High pressure gas is an incredible source of energy and is very dangerous. However, filling the tank can be done safely using the carrier refill setup. Pressure gauge To P psi (12,405 KPa) carrier refill line Needle valve CGA 580 fitting Supply tank valve Transfer line with Swagelok fittings Figure 7 Overpressure vent Supply tank Carrier refill setup p/n PNU-2058 Caution For your safety, read the steps that follow before making any connections. 22

29 MADE IN U.S.A. Installation Filling the P200 internal carrier gas cylinder Cylinder specifications: The P200 Gas Analyzer is equipped with a refillable carrier gas cylinder. This cylinder is U.S.D.O.T. rated at 1800 psig ( 12,405 KPa ) maximum with a 5 year Hydrostat approval. Components Required: 1. P200 Refiller Apparatus, PNU P200 Micro Gas Analyzer 3. Bulk Carrier gas cylinder ( 1800 psi/12,405 KPa or less ) with CGA-580 fittings Caution Hewelett-Packard is not responsible for personal injury or damage to equipment as a result of filling gas cylinders with this apparatus. To avoid injury, the following steps should be followed. 1. Connect the P200 refiller apparatus to the supply tank ( 1800 psi/12,405 KPa or less ) via the CGA-580 fitting ( Figure 7 ). To avoid leaks, use an adjustable wrench and securely tighten the connections. 2. Make sure the needle valve of the refiller apparatus is fully closed by turning the needle valve clockwise until firmly seated. 3. Slightly open the valve on the supply tank. No gas should flow at this point. HMODEL: SERIAL NO.: COL. A: COL B: Carrier jumper tube "A" Carrier filler/carrier in port Figure 8 Back of P200 23

30 Installation Filling the P200 internal carrier gas cylinder 4. Connect the 1/8 inch tube from the filler apparatus to the "Carrier Filler/ Carrier In Port" of the P200 back panel via the Swagelok bulkhead fitting (Figure 8). Finger tighten and then loosen 1/4 turn. 5. Slightly open the needle valve on the refiller apparatus and listen for gas leaking through the loose 1/8 inch fitting on the back panel. This purges the refilling apparatus transfer lines so that no air enters the P When the transfer lines have been sufficiently purged (about 15 seconds), turn the needle valve on the refiller apparatus clockwise until seated and then tighten the 1/8 inch fitting on the back panel of your P200. If your P200 carrier gas cylinder has not been completely emptied or you are not changing to a different carrier gas, go to step To purge air or a different carrier gas from your P200 carrier gas cylinder, you must first loosen the Swagelok fitting that secures the carrier jumper tube ("A" Figure 8) to the "CARRIER IN" port on the P200 back panel. 8. If the P200 carrier gas cylinder contains an unwanted carrier gas, you may empty it at this time by turning the Carrier On/Off control valve on the P200 front panel ( Figure 6) to the "On" position. When you no longer hear gas escaping, ensure that the Carrier On/Off control valve is "Off". 9. Slowly open the needle valve on the refiller apparatus until you see an increase in pressure on the refiller apparatus pressure gauge. 10. When you see and indication of approximately 500 psi, turn the Carrier On/ Off control valve ( Figure 6) to the "On" position. You will hear a rush of gas escaping from the end of the carrier jumper tube. When the Gauge needle returns to zero, turn the Carrier On/Off control valve to the "Off" position. The pressure gauge needle will begin to rise again. When the gauge needle again reaches 500 psi, repeat the process. For best results, the P200 carrier gas cylinder should be purged, as described above, a minimum of three times. 11. Close the needle valve on the refiller apparatus. 12. Tighten the Swagelok connection between the Carrier Jumper Tube ("A"Figure 8) and the "CARRIER IN" port on the P200 back panel. 24

31 Installation Verifying installation 13. Observe the pressure gauge in the refiller apparatus. Slightly open the needle valve on the refiller apparatus. When the pressure on the gauge reads 1500 to 1800 psig, close the needle valve on the refiller apparatus. Do not exceed 1800 psig ( 12,405 KPa). WARNING If pressure in the P200 tank exceeds 1800 psig/ 12,405 KPa during filling, you will hear a relief valve on the refiller apparatus open. A loud startling noise continues until the supply tank pressure is at 1800 psig/12,405 KPa. 14. Completely close the valve on the supply tank and disconnect the 1/8 inch tube from the back panel of your P Replace the Swagelok cover fitting over the carrier fill inlet. Verifying installation In order to operate your P200/ P200H Micro GC you will need a computer with the Agilent EZChrom 200 software and the GC Tools Programs. The computer and software will allow you to send a method to your analyzer and to verify that communication has been established between the computer and the P200/ P200H. This section assumes that your software has been installed on your computer. Refer to the GC Tools User s Manual for an explanation on how to use the GC Verification Tool should you have difficulty establishing communications between your computer and GC. To verify proper function of your Micro GC 1. Double click on the EZChrom 200 icon in the HP Window to open the program. 2. In EZChrom, click on the Instrument menu on the main menu bar (Figure 9): Figure 9 EZChrom menu bar 25

32 Installation Verifying installation 3. Click on Status. If using the keyboard, type: <T>. A status window should appear in a few seconds (Figure 10): Figure 10 Instrument status window Parameters for items in the status window should be within the ranges shown in Table 2. Table 2 Parameter Status Parameters Range Column temp 30 C to 180 C Pressure 5 to 45 Auto zero 419 to +419 Detector filament Heaters ON Battery % 14 to 100 OFF/HTG/RDY (P200H only) 4. If all items in the window are within the parameter limits, your system installation is correct. Should the status window fail to appear or should items fall outside given parameters, consult the Troubleshooting Chapter of this Manual. 26

33 Installation Sample connections 5. Press <Enter> or click on [OK] to close the status window. Sample connections When connecting a sample to your analyzer inlet port, you may want to use an inlet filter and/or a flow meter to ensure troublefree operation. The filters The P200/ P200H contains several internal filters. The sample inlet contains a 10µ filter and the injector contains two built-in 5µ filters. These filters protect the fine passages inside the instrument. However, only authorized personnel can replace these filters, therefore it is to your advantage to install the optional external sample filter kit (KIT-2052) to protect the internal filters whenever you suspect that particulate matter may be present. Droplets of oil or water should be removed before attempting to run a sample. An installation diagram for the external 10 µ sample filter kit is shown in Figure 11. Sample inlet port Two holed ferrule 10 µ Filter assembly Sample line 1/16" Nut Front panel Dual end ferrule Figure 11 External filter installation 1/16" Swagelok unit The External Sample Filter Kit contains the parts listed below (Table 3): 27

34 Installation Sample connections Table 3 External Sample Filter Kit (Kit 2052) Item p/n Quantity Description 1 MCH Sample filter cartridge 2 KIT /16 inch Swagelok union, SST 3 FRI Dual end ferrule 4 FRT micron replacement filters The flow meter The sample inlet of the Micro GC can withstand sample pressures from 0 to 30psi. The flow meter will allow you to reduce the flow of high pressure samples (up to 1000psi) and monitor the flow of gas going into the instrument s sample inlet line. Because the flow meter is not heated, it is recommended for use with the P200 only (not the P200H). A typical flow meter gas path is shown in Figure

35 Installation Sample connections To sample reservoir [1000 psi max.] Sample flow controller Flow control knob Vent Rotameter BTU gas analyzer M/P unit support bracket Figure 12 Sample flow controller module Caution Moisture-containing samples, hot samples (above ambient temperature) and/ or samples containing particulates may damage the P200. Samples above 110 C and/ or samples containing particulates may damage the P200H. Precautions with these samples must be taken or you will void the warranty. 1. Connect your sample container to the flow meter and fasten the connections with a wrench. 2. Connect the flow meter outlet to the GC inlet, but leave the connections slightly loose to allow you to purge the lines with the sample. The sample/ calibration gas should be within 5 C of ambient room temperature and generate a pressure between 0 and 1000 psi gas. 3. Open the valve at the standard container to allow the sample to flow into the flow meter. Adjust the flow to read 4cc/min by observing the flow meter. 29

36 Installation Running a sample 4. Let the sample gas purge the lines. Sample gas will exit through the loose connection between the flow meter outlet and the GC inlet. 5. Allow sufficient time for the transfer lines to be cleared of air. Using a wrench, securely tighten the fitting at the GC sample inlet. Running a sample To run a sample, make sure the GC has received the method chosen to run the analysis and the conditions are stable. This procedure assumes you have established a method in your computer suitable for the analysis of your sample. A good place to start is by running a calibration standard similar to the one used to test the P200. A copy of the chromatogram and a printout of the instrument conditions is shipped inside the instrument folder that accompanies your P200. However, if your P200 is part of a BTU Analysis system, you should follow the BTU User s guide instructions on how to run a calibration standard. 1. At the EZChrom Main Menu bar, click on Instrument. 2. Click on Send the Current Method. The method that appears when you first boot up is the one last used either at the factory or by the last user of the GC. 30

37 Installation Running a sample Figure 13 Status window 3. After the method transfers to the GC, allow several minutes for the column temperature to equilibrate. At the Instrument pull-down menu, click on Status. 4. In the GC Status window (Figure 13) the parameters in the window will be those of the method you sent from the computer to your GC. When temperatures have stabilized, they will fluctuate only 1 C. 5. Click on [OK] to leave the Status window. 6. At the EZChrom Menu bar, click on Start (Figure 14): Figure 14 EZChrom menu bar 7. At the Run window, click on [Start]. 8. Compare your chromatogram with the one shipped with your unit. More detail instructions on how to run a sample can be obtained from your EZChrom or BTU Users Manuals. 31

38 Installation Running a sample 32

39 4 Hardware Description

40 Hardware Description This section gives detailed information on the P200/P200H hardware. Front panel The front panel of the P200/P200H (Figure 15) includes the following: Carrier gas gauge This gauge indicates the pressure in the P200/P200H internal carrier gas tank. Carrier on/off Carrier gas gauge Gas sample inlet OFF ON GAS SAMPLE ONLY H WARNING! 110º C CAUTION: SAMPLE INLET(S) HOT CARRIER CARRIER Power on/off POWER SERIAL P Series Serial port Figure 15 P200/P200H front panel Power on/off This button turns power on or off to the entire system including the detector filaments. The green light on the button acts as an internal battery charge and power cutoff circuitry indicator. 34

41 Hardware Description Front panel Caution Do not power up the GC unless the carrier gas is on. The presence of air inside the detector cell will cause a rapid rise in the filament temperature. This may result in irreversible damage to the detector. Serial port The serial port of the front panel is the same as the serial port on the back panel of the P200/ P200H. Two ports are available for convenience purposes. This serial port is made through a female DB-9 connector which conforms to the RS-232 standard. Agilent Technologies has several types of cables available to correspond to different PC connectors (Table 4). Table 4 Serial Interface Cables Signal name from PC P200 pin # DB-9 male Cable CBL-1482 DB-25 female DCD 1 held true 8 1 RXD 2 TXD 3 2 TXD 3 RXD 2 3 DTR 4 ignored 20 4 SIG, Gnd DSR 6 held true 6 6 RTS 7 ignored 4 7 CTS 8 held true 5 8 Cable CBL-1010 DB-9 female Gas sample inlet The sample inlet, a 1/16 inch Swagelok union containing a 10µ frit, is located in the center of the upper edge on the P200H (see Figure 15). The inlet on the nonheated P200 is located to the right of the front panel serial port. With either instrument, use a compression fitting at this inlet to connect to a sample line. The inlet on the P200H is heated electrically to 110ºC. 35

42 Hardware Description Back panel WARNING Contact with the gas sample inlet on the P200H after it has reached the set temperature will cause burns. Carrier on/off This valve opens and closes the carrier flow from the internal tank to the system at 80psi. Back panel The back panel of the P200/P200H (Figure 16 ) is split into two parts to correspond to two separate compartments inside the unit. Analog/control A&B Serial I/O Power12VDC ANALOG/CONTROL SERIAL I/O AUX 12VDC IN Vents COL A VENT A & B RS-232 SAMPLE VENT POWER 12VDC COL B VENT CARRIER FILL 1800 PSI MAX CARRIER OUT REF A VENT CARRIER IN REF B VENT COLUMN A PRESSURE COLUMN B PRESSURE H Column A&B pressure controls Figure 16 P200/P200H back panel Left back panel The left back panel corresponds to the GC compartment that contains the GC chassis, the two GC modules, the pneumatics and the controller board. 36

43 Hardware Description Back panel Power 12 VDC A round black female connector allows you to plug the 12 VDC recharger to the P200/P200H. If connecting to voltage greater than 115 volts, make sure the power supply is for the correct line voltage. The 12 VDC power supply recharges the sealed lead-acid battery inside the P200/P200H whenever the power switch is turned off. For battery charging instruction, see Chapter 3. Whenever possible run your P200 with the 12 VDC power supply connected to the power line. This prolongs the life of your internal battery and eliminates the need to recharge it often. When the internal battery needs replacing, the procedures which should be followed are covered in Chapter 7 of this Manual. Serial I/O RS-232 connector This connector enables control of the GC from a computer data system. Pin assignments are the same as those described in Table 5 for the front connector. Analog control (A & B) The analog/control port enables the signal to be transmitted to data collecting or instrument control devices. The analog connector provides pins that allow you to control the Start function of the GC through analog signals. In addition, you can take the analog output of channel A and B detectors to a third party data system. Vents The back panel of the P200 contains four color coded vents for both column A and column B (sample is red and reference is green) and a fifth sample vent (white) coming from the sample pump. For protection and to avoid contamination, the vents are closed using Luer-Lock plugs when the unit leaves the factory. 37

44 Hardware Description Back panel WARNING The Luer-Lock plugs must be removed when the unit is operating. Save plugs to use for long term storage. Table 5 Analog Control Pin Assignments Pin number Description Pin number Description 1 Ready in 8 A-analog 10 volt 2 Start in 9 Digital ground 3 Start out 1 10 Ready out 1 4 Start out 2 11 Ready out 2 5 B analog 1 volt 12 Chassis ground 6 B analog, 10 volt 13 B analog return 7 A analog, 1 volt 14 Chassis ground 15 A analog return Control A and B pressure controls The two controls are used to set the column head pressure. This parameter setting strongly influences the retention time and separation of the components being analyzed. P200 instruments ussed for BTU analysis require the use of a flat blade screwdriver to change the settings. Caution Consult either the BTU or the EZChrom User s guide for instructions on how to set column head pressure. 38

45 Hardware Description Right panel Table 6 P200 Instrument parameters Parameter Range Function Column temperature C Control the column oven heaters. Sample time seconds Time for the vacuum pump to draw sample through the loop at a flow of 8 cc/min. Inject time milliseconds Determines the amount of sample injected into the column. For tens and percent concentration 40 msec is recommended. For low levels, 100 to 200 msec. Detector filament On/Off Turns the filament current Off and On. Auto zero On/Off Zeroes the detector filament in between runs. Detector sensitivity Low, medium, high The three settings differ by a factor of 10 (5, 50, 500). Right panel The right back panel corresponds to the compartment containing the internal battery and the internal carrier gas cylinder. ANALOG/CONTROL SERIAL I/O Carrier gas jumper line Auxiliary 12VDC AUX 12VDC IN A & B RS-232 POWER 12VDC CARRIER FILL 1800 PSI MAX 1800psi tank inlet COL A VENT SAMPLE VENT COL B VENT CARRIER OUT COLUMN A PRESSURE REF A VENT CARRIER IN COLUMN B PRESSURE REF B VENT Carrier out H Carrier In Figure 17 P200/P200H back panel 39

46 Hardware Description Right panel Carrier gas jumper line The jumper line brings the carrier gas from the internal gas cylinder (carrier out) to the GC components (carrier in), injector, columns and detector of both modules. If using an external carrier gas source, first turn off the internal carrier gas main valve on the front panel, then disconnect the jumper at Carrier In and connect the alternate carrier (regulated to 80 psi) to the inlet line (Figure 17). Caution Make sure power is off before disconnecting the carrier gas jumper line. Caution Your unit has been set for either hydrogen/helium or nitrogen/ argon as the carrier gas. If argon or nitrogen is used, certain switch settings in the mother board will need to be changed to avoid damage to the detector filaments. See Chapter 6 for instructions. Auxiliary 12 VDC The auxiliary 12 VDC allows you to run your P200/ P200H from any other 12 VDC power source such as a vehicle cigarette lighter plug psi inlet This inlet provided is used to recharge the P200/ P200H internal carrier cylinder. Installations on how to perform these operations were covered in Chapter 2 of this manual. Carrier outlet The carrier outlet on the right back panel connects a stainless steel jumper tube to the carrier inlet on the back left panel. When the front panel carrier gas knob is turned on, carrier gas is released through this outlet at 80 psi. 40

47 Hardware Description Internal components Carrier inlet The carrier inlet on the left back panel connects to a stainless steel jumper tube to the carrier outlet on the back right panel. When the front panel carrier gas knob is turned on, carrier gas flows into the inlet at 80 psi. Internal components This chapter describes the main components inside your P200/ P200H case (Figure 18). Component details are located in Chapter 6 where the GC assembly and disassembly is discussed. WARNING To avoid damage to your unit, do not remove the P200/ P200H cover while power is on. Turn the power off and disconnect the 12 VDC power supply. The P200/ P200H contains two main internal compartments, each with its own back panel fastened to the P200 frame by four Phillips head screws. Facing the front panel, the right compartment contains the mother board which rest over the pressure control regulators for channel A and B. Partially covered by the board are the two GC modules. Module B is to the left and Module A is to the right. Jumper Battery Check valve Internal carrier gas tank Controller board Labels Regulator Modules Figure 18 Internal P200 components (top view) 41

48 Hardware Description Internal components The left compartment contains the 300 ml gas cylinder, the cylinder pressure regulator, the connecting tubes to the Carrier Out and the1800 psi carrier refill ports. Under the gas cylinder is the 5 amp/ sealed lead acid battery. The main power line is also routed to this compartment. The Front Panel carrier gauge shows the pressure of the internal carrier gas cylinder and allows you to determine when it needs refilling. The EZChrom Instrument Status window displays the % battery charge to help indicate when the battery needs recharging. Modules Inside each module is a complete gas chromatograph consisting of a micro injector, columns (analytical and reference), column oven, universal micro solid state detector and heaters (Figure 19). The module can be easily exchanged by following directions in Chapter 7. However, individual components can only be exchanged at the factory. 42

49 Hardware Description Internal components Columns Micro injector Carrier and sample lines Vents Universal solid state detector Figure 19 GC module components Observe that each module has an outside label (Figure 20). This clearly identifies the column type, length, heater scale and the offset. Scale and offset will be discussed in Chapter 7, since they need to be considered or are important when exchanging modules. H S/N: DATE OF MANUF.: COLUMN TYPE: COLUMN TEMP. OFFSET: MAX COLUMN TEMP.: COLUMN TEMP. SCALE: Figure 20 Module label INJECTOR TYPE: FIXED LOOP INJ. TIME: MADE IN USA 43

50 Hardware Description Internal components Also note that the controller board has a label similar to those on the outside of the modules. The label is affixed to the aluminum box attached to the controller board. It lists important information you will need if reentering the instrument configuration. Chapter 6 will provide additional details on the instrument configuration. Fuses There are 3 amp fuses in the GC. The first is on a small, printed circuit board that rests on the GC compartment dividing wall. It protects the unit from auxiliary power source surges. The second fuse is for the cable power and can be found inside the line coming from the main power switch. A third fuse protects the unit and is found in the controller board, if a fuse burns out, replace the fuse with a 3 amp fuse that has the same characteristics as those presently in your GC. 44

51 5 Columns

52 Columns Chapter 5 describes the various column options available for the M200/M200H micro GC. Descriptions include the stationary phase type, applications, typical chromatograms and common column conditions. Introduction The column is the basis of gas chromatographic separation. It is the column that contains the stationary phasae which can either be solid or liquid. Therefore, there are two types of gas chromatography; gas solid chromatography (GSC) and gas liquid chromatography (GLC). In GSC, a solid stationary phase separates components by the differing component affinities to the active sites. Different affinities cause components to be delayed different amounts of time as they move through the column. Example of GSC columns are the PoraPLOTQ, PoraPLOTU, molecular Sieve 5A PLOT, and Al 2 O 3 /KCl PLOT. In gas liquid chromatography (GLC), the stationary phase is a liquid coated on a solid support. The components dissolve in the liquid coating, forming an equlibruim between the stationary and the mobile phases. The variance in solubility for different componetns cause component separations. For example, OV-1, OV-73 and OV-1701 are GLC columns. 46

53 Columns Introduction Table 7 Columns Part number Application Dimensions/stationary phase OPM-0104 Analysis of non-polar compounds 4 meter 0.15 mm ID, 1.2 µ df, OV 1 OPM-1704 Analysis of mid polar compounds 4 meter 0.10 mm ID, 0.5 µ df, OV 1701 OPM-7304 Analysis of non polar compounds 4 meter 0.10 mm ID, 0.5 µ df, OV 73 OPM-AL10 OPM-HA25 OPM-MS04 OPM-WX04 OPM-PQ04 OPM-PQ08 OPM-PU04 High resolution column for analysis of C1-C5 hydrocarbons Analysis of fixed gases and light hydrocarbons, C0 2,H 2 S, SO 2, CH 4,C 2 H 6,C 2 H 4, C 2 H 2, C 3 H 8 High resoultion column for the analysis of permanet gases H 2, O 2, N 2, CO, CH 4, noble gases High resolution column for the analysis of alcohols and other polr volatile hydrocarbons. Analysis of fixed gases and light hydrocarbons, CO 2, CH 4, C 2 H 6, C 2 H 4, C 2 H 2, and C3, C4, C5 isomers High resolution column for the analysis of fixed gases and light hydrocarbons CO 2, CH 4, C 2 H 6, C 2 H 4, C3 Analysis of fixed gases and light hydrocarbons, CO 2, CH 4, C 2 H 6, C 2 H 4, C 2 H 2, H 2 S, COS, SO 2 and C3, C4, C5 isomers 10 meter mm ID, 0.5 µ df, Al /KCI PLOT 25 cm 0.5 mm ID, packed, HayeSep A 4 m mm ID, 30 µ df, molecular sieve 5A PLOT 4 m mm ID, 0.5 µ df, carbowax 4 m mm ID, 10 µ df, PoraPLOT Q 8 m mm ID, 10 µ df, PoraPLOT Q 4 m mm ID, 10 µ df, PoraPLOT U 47

54 Columns Analysis conditions Part number Application Dimensions/stationary phase OPM-PU06 Analysis of fixed gases and light hydrocarbons, CO 2, CH 4, C 2 H 6, C 2 H 4, C 2 H 2, H 2 S, COS, SO 2 and C3, C4, C5 isomers 6 m mm ID, 10 µ df, PoraPLOT U OPM-PU08 Analysis of fixed gases and light hydrocarbons, CO 2, CH 4, C 2 H 6, C 2 H 4, C 2 H 2, H 2 S, COS, SO 2 and C3, C4, C5 isomers 8 m mm ID, 0.5 µ df, PoraPLOT U OPM-XXX Custom column configurations 2 to 10 m 0.1 to 0.32 mm ID or micropacked 25 cm to 60 cm, 0.5 mm ID Analysis conditions As discussed in Chapter 2, column temeperature and carrier gas flow are the physical properties affecting Micro GC separations. Column temperature affects solubility of components in the stationary phase. Carrier gas flow affects the rate at which the components in the mobile phase travel through the column. In order to optimize the separation of components, a balance between column temperature and carrier flow must be achieved. This is known as method optimization. This chapter provides "average" column conditions and chromatograms that may be used as a starting point in method development process. When your instrument is shipped, it includes a folder that contains a test chromatogram and its conditions. This is a great place to start setting conditions for general gas analysis applications. 48

55 Columns Analysis conditions Molecular Sieve 5A plot (MS5A) The MS5A column separates hydrogen, oxygen, nitrogen, methane, carbon monoxide and selected noble gases. Using its 5 Angstrom pore size sieve the column separates components by molecular size and configuration. Molecular Sieve stationary phases are notorious for absorbing water (eg. moisture in air), which affects its separation ability. Therefore, periodic column conditioning is required (refer to column conditioning). To determine if column conditioning is necessary a simple test can be done. Analyze a sample of ambient air. If no separation of air into oxygen and nitrogen occurs, reactivate the column by conditioning. A typical chromatogram for the analysis of fixed gases is shown in Figure 21. Typical conditions for the analysis of fixed gases are: Column: Column head pressure: Carrier gas: 4 m mm ID, 30 um d, molecular sieve 5A Plot 30 psi Helium Column temperature: 45 C Detector sensitivity Run time: Sample time: Injection time: Run time: High 30 seconds 15 seconds 50 milliseconds 60 seconds 49

56 Columns Analysis conditions Consult the EZChrom User s Guide for Instrument Setup instructions Peak identification: 1. Hydrogen % 2. Oxygen % Nitrogen % 4. Methane % 5. Carbon monoxide -1.00% Time (seconds) Figure 21 Fixed gases: transformer gas analysis on a MSSA column 50

57 Columns Analysis conditions HayeSep A(HSA) This micropacked column separates oxygen/nitrogen (air composite), methane, carbon dioxide, ethane, acetylene, propane and selected sulfur gases. Compounds larger than propane take a long time to elute from this column. Molecules larger than propane are better analyzed on any of the OV columns. A typical chromatogram is shown in Figure 26. Typical conditions for an analysis are: Column Column head pressure Carrier gas 25 cm 0.15 mm ID, 100/120 mesh HayeSep A 17 psi Helium Column temperature 52 C Detector sensitivity Sample time: Injection time Run time Low 10 seconds 50 milliseconds 80 seconds 51

58 Columns Analysis conditions 2 Peak identification: 1. Nitrogen 2. Methane 3. Carbon dioxide 4. Ethane 5. Propane Time (seconds) 80 Figure 22 Hydrocarbons C1 to C3: Natural gas analysis on a HSA column 52

59 Columns Analysis conditions OV-1 and OV-73 These two columns separate nonpolar compounds by boiling points. These columns are ideal for the analysis of natural gas. A typical chromatogram for the analysis of natural gas is shown in Figure 23. Typical conditions or an analysis are: Column 4 m mm ID, 1.2 µ d f, OV-1 Column head pressure 23.2 psi Carrier gas Helium Column temperature 40 C Detector sensitivity Medium Sample time: 10 seconds Injection time 50 milliseconds Run time 95 seconds 53

60 Columns Column conditions Peak identification: 1. Composite 6. n-pentane 2. Propane 7. Hexanes 3. i-butane 8. Heptanes 4. n-butane 9. Octanes 5. i-pentane Octanes Time (second) 95 Figure 23 C 3 to C 8 - natural gas analysis on an OV-1 column OV-1701 The OV-1701 column separates mid polar compounds by boiling point. This column is also ideal for hydrocarbons from C4 and beyond. Column conditions Certain columns such as the MS5A and the Al 2 O 3 /KCl PLOT become slowly deactivated at normal operating temperatures. Deactivation is caused by the absorption of certain compounds such as water and carbon dioxide. This is indicated by decreased separation caused by the active sites in the stationary 54

61 Columns Column conditions phase being covered. Figure 28 showws a deactivated MS5A showing poor separation, one after 1000 injections of air saturated with water vapor. Figure 24 Poor separation on a molecular sieve column Caution Not all columns tolerate the same high temperatures as the molecular sieve columns. For example, the HAyeSep A column deteriorates above 160 C and a TCEP columns above 110 C. Once a column is damaged, the column and possibly the detector may need replacement. Please contact Agilent Technologies for maximum temperatures of your column. To condition a column 1. At the EZChrom Main menu bar, select Method then Instrument setup. You will access the Instrument Setup window Figure 25. To avoid discharging the P200/P200H internal battery, use the battery charger during the conditioning procedure. 55

62 Columns Column conditions Figure 25 Instrument setup window 2. Set the temperature for the molecular sieve 5A PLOT or Al 2 O 3 /KCl PLOT column to 180 C. 3. Click on Method then on Save As. Enter an eight character name with the extension ".met". For example, name the method bakeout.met. this will be your column conditioning method. 4. Click on Instrument then on Send Current Method. Leave the instrument on with carrier flowing for a minimum of four hours, or overnight for maximum benefit. This cleans the column of moisture and resuidues left from prior runs. 5. To end conditioning process, click on Method, then click Open and choose your original method. Send Current Method to the GC. this will reset the temperature conditions for the analysis. 6. Click on Instrument and Status to check that the instrument conditions are those of the original method. 56

63 6 Theory of Operation

64 Theory of Operation This section begins with a description of the P200 Gas Chromatograph electronic block diagram. It is then followed by a discussion of the P200 pneumatic schematics. Understanding the function of the main components of the P200 will make it easier to understand its operation and will aid in problem isolation during the Troubleshooting Section. Electronic block diagram The P200/ P200H Micro GC is a microprocessor controlled instrument with easily identifiable major electronic blocks and signal paths. The blocks include the channel module electronics (one for channel A and an exact replica for channel B), the main PCB electronic board and a series of analog and data paths used to receive or send information. Figure 26 is the electronic block diagram of the P

65 Theory of Operation Electronic block diagram User connections Start and ready out ^ Start and ready in Serial I/O RS VDC connector 10V. Analog out (Ch A) 1V. Analog out (Ch A) Status LED ^ Sync. logic Diagnostic sensors < > < > Data status out MICROPROCESSOR Serial out Serial in Instrument control in Power supplies Channel B analog outputs/ inputs Channel A amp Ω Autozero voltage ± 2 mv steps > 1/10 Detector sensitivity low, med, high (Gain=5,50,500) > TCD Detector signal > Constant voltage driver RAM EPROM Battery backup Digital/analog converter > < < Microprocessor bus ^ Power control ^ Valves and vacuum pump Analog digital converter Reference and diagnostics inputs ^ Power control ^ Column heater ^ Analog multiplexer ^ ^ Column temperature sensor Channel B duplicate electronics of channel A Column pressure sensor Figure 26 P200 electronic block diagram 59

66 Theory of Operation Electronic block diagram Printed circuit board The main printed circuit board contains most of the electronics in the P200/ P200H GC. It provides all control functions for the detector, valves, heaters and other chromatographic hardware. All hardware such as the sampling pump, column heaters, temperature sensors and the column pressure sensor connect to the board on the left portion of the block diagram. The rear panel connections are on the right of the diagram. Ports The diagram shows only the back Serial I/O RS-232 port. The front RS-232 port is an exact duplicate of the back port and is not shown. Also, because the second channel is an exact replica of the first channel (Channel A), it is not shown. Each control block connects directly to the microprocessor bus which runs across the full width of the diagram. The operational parameters for the blocks as well as the status data transfer over the bus directly to the microprocessor (the shaded block in our diagram). This design eliminates any need for mechanical switches, potentiometers and/or meters. All the parameters that the P200/ P200H microprocessor needs to operate the GC must be received through the serial port input (either at the front or back of the P200/ P200H). Parameters are only accepted from one port at a time to avoid ambiguity. A logic switch determines from what port to accept a signal. Normally, the back panel port is active. Instrument status parameters (temperature, column head pressure) are sent from the instrument to the PC through the RS-232 port. During a run, this connector also carries the digitized detector signal output that the EZChrom software needs to process the chromatograms and perform measurements. EPROM and RAM The EPROM stores the control program, while the RAM stores all the method parameters (set points), hardware configuration values and temporary 60

67 Theory of Operation Electronic block diagram information for a run. An internal battery maintains the contents of the RAM chip. Chromatographic data or results are not kept within the P200/ P200H. The P200/ P200H stores only instrument control parameters. However, the RS-232 port sends out data to the computer. EZChrom software collects, manipulates and processes this information. Analog to digital converter The Analog to Digital Converter (ADC) takes any analog input that needs to be digitized and translates them. The microprocessor selects what signal will be digitized at a given time by selecting what input of the Analog Multiplexer is to be connected to the ADC. The detector signal from either Channel A or B can be selected as well as a variety of reference and diagnostic inputs. Detector The universal micro Solid State Detector (SSD) is a four filament resistive bridge. The sample effluent from the analytical column flows over two filaments and the flow from the reference column flows over the other two filaments. In addition, the jumper in the controller board controls the current to the filaments. This current change is for applications using argon or nitrogen as a carrier gas. Caution Using an incorrect jumper setting will damage the filaments. An auto-zero voltage generated by a digital to analog converter (DAC) sums the detector output signal. The DAC cancels the offset voltage of the bridge when no sample is present. EZChrom 200 controls the sum of the signal and the amplification by choosing Low, Medium or High sensitivity. This choice changes the amplifier gain from 5, 50, and 500. Dividing the output by 10Ω through a resistor creates a one volt output. The front and back panel ports provide the full detector output. 61

68 Theory of Operation Electronic block diagram Power blocks The microprocessor controls two power blocks. One operates the timing of the injector valves and the operation of the sample vacuum pump. The other controls the column heater. The method stored in EZChrom controls the timing of the valves and the pump. The microprocessor receives the temperature sensor signal and controls the heater duty cycle to maintain the instrument temperature set point you have chosen in your method. Diagnostic sensors The status LEDs (diagnostic sensors) are a valuable aid in troubleshooting the P200/ P200H. They are mounted internally to the controller board and are used to isolate problems to the main board or to the external power supply. Other sensors check the operation of the power switches for the valves and heaters. Logic synchronization block The Logic Synchronization block orchestrates the operation of the P200/ P200H with external devices. One contact closure signals when the GC is ready to sample. Another closes momentarily when an injection is made. The START and READY inputs are pulled up to the internal logic supply. Any external devices that use these inputs must connect them to the P200/ P200H ground. The synchronization connections, along with the analog signal outputs are available at a DB-15 connector in the rear panel. This connector provides signals for both Channel A and Channel B (the illustration shows them separate). You can therefore tap the signals for either channel at this connector. Check Table 5 on page 38 for a description of the pin assignments. Instrument configuration parameters As stated earlier, each module and controller board have unique parameters critical to the operation of the P200/ P200H. The battery protected RAM stores the parameter that regulate the performance of the column heaters and column 62

69 Theory of Operation Pneumatic schematics head pressure sensors. These values are entered on a label on the controller board unit when tested at the plant (See Figure 20). After exchanging a module, controller board or pressure transducers the instrument configuration parameters must be reset. Also, it is possible for the parameters to change or become scrambled due to electronic "glitches", improper connection to external devices or simply due to the failure of the backup battery. Pneumatic schematics The P200 GC contains all the basic components of any gas chromatograh in a simple modular design. The modular design diminishes dead volume to maximize efficiency, increase reliability and provide ease of operation. Carrier gas flow path Located inside the left compartment (as you face the front of the P200) is the internal carrier gas cylinder (A) (Figure 26, on page 59). The tank is filled at the carrier fill 1800 psi inlet (B). The carrier fill inlet contains a check valve (C) to prevent overfilling. Pressure at the tank can be monitored at a front panel gauge (D). An On/Off front panel knob (E) opens and closes the flow that comes from the pressure regulator (F) that has been factory set to 80 psi. The carrier gas then travels towards the back of the unit to the carrier outlet (G). A stainless steel jumper tube (H) takes the carrier to the carrier inlet (I) on the back panel of the P200. The carrier is split into two streams, each going to its own manifold and pressure controller (J). From each manifold, the carrier gas continues to the injector (K) inside each module (L). The flow goes through the analytical and reference columns (M), to the detector (N) and out through the vents (O). Pressure at the head of the column is monitored by a pressure transducer which generates an analog signal that is digitized at the controller board. The pressure is displayed in EZChrom s Instrument Status window. 63

70 Theory of Operation Pneumatic schematics H B G I C O O A J J K N K N F M L M L D ON E OFF A- Internal carrier gas cylinde G- Carrier outlet M- Analytical/reference columns B- Carrier fill 1800 psi inlet H-Jumper tube N- Detector C- Check valve I- Carrier inlet O- Vents D- Pressure gauge, front panel J- Pressure regulator E- Carrier on/ off knob K- Injector F- Internal pressure regulator L- Module Figure 27 Carrier gas flow path 64

71 Theory of Operation Pneumatic schematics Sample flow path The gas sample enters the GC at the sample inlet (see Figure 28). The connected sample, ranging in pressure from 0 to 30 psi flows through two separate sample lines held together by a two-holed ferrule. The sample flows to the sample microvalve at the injector. The instrument receives a signal from EZChrom to begin an analysis. The vacuum pump activates and draws the sample through the now open sample valve. The sample enters the sample loop and exits to vent until the user selectable sample time is completed. The sample valve closes, the pump stops and the loop pressurizes. The inject valve then opens for a user selectable inject time, allowing sample to be swept onto the analytical column. The analytical and reference column flow passes through a solid state detector and the flow exits at the back of the unit through the vents. 65

72 Theory of Operation Pneumatic schematics Alternate carrier gas option Microvalve Channel B column Manifold Vents Injector & microvalves Manifold A Detector Detector Channel B vents Sample inlet 0-30psi Microvalve Channel A column Injector & microvalves Detector Vents Manifold Manifold B Vacuum pump Sample pump Carrier in 80psi Channel A vents Vacumn pump vent Figure 28 Sample flow path On occasion, it may be necessary to change the carrier gas from helium/hydrogen to argon/nitrogen or vice versa. When using argon, be aware that its thermal conductivity will make the detector filaments run much warmer at the same voltage level than with helium hydrogen. WARNING Running the SSD with argon or nitrogen at the settings intended for hydrogen or helium will irreparably damage the detector. The GC controller board has two jumper switches enabling you to decrease the voltage level from the standard 20 Volts to 8.5 Volts. This voltage matches the 66

73 MADE IN U.S.A. Theory of Operation Pneumatic schematics argon/ nitrogen filament temperature to the helium/ hydrogen filament temperature. The following procedure for changing carrier gas assumes that you are viewing the P200 from the front. WARNING Disconnect all power and turn off the instrument before removing the top cover. 1. Remove the four screws that fasten the top cover to the frame and lift the cover up. 2. Observe the aluminum box (Figure 29) seated close to the edge of the board with the serial number and scale information. On each side of the box there are two jumper switches labeled JP4 and JP5. They are for Channel A and B respectively. The printed circuit board has markings indicating the correct position for each carrier gas jumper (HE for helium and hydrogen, and AR for argon and nitrogen). 3. Remove the jumper to uncover the three pins on the board. Move the jumper to the AR label. When the jumper is positioned for argon, the pin next to the AR label will be covered as shown in Figure 29. Ar Ar JP5 He JP4 He HMODEL: SERIAL NO.: COL. A: COL B: Figure 29 Alternate carrier gas jumper switches 67

74 Theory of Operation Pneumatic schematics 4. Plug the inverter printed circuit board (PCB-2017) between the detector ribbon cable and the J9 and J2 connectors on the controller board. The inverters are small printed circuit boards with two connectors. One mates to the ribbon cable coming from the module; the other connects where the ribbon cable normally plugs when using helium or hydrogen as the carrier. When using argon, the difference in thermal conductivity of many gases will generate many negative peaks. When using argon as the carrier gas, it is strongly recommended that you use the detector signal inverter. 5. Ensure cables, inverters and jumpers are correctly plugged and properly seated. 6. Put the cover back on and fasten it to the frame with the four screws. 7. Connect the carrier gas (when using an external source, set pressure to 80psi) and let it purge for several minutes. Turn the instrument on and try a sample run. You will have to adjust your method because the new carrier gas will reduce peak sizes and shapes. 68

75 7 Troubleshooting

76 Troubleshooting This section begins with a troubleshooting guide listing problems and their possible cause. This section also shows you how to exchange different assemblies and/ or parts of the P200 and P200H. Troubleshooting The troubleshooting section is composed of a series of tables, each addressing a particular problem. Within each problem, you may be referred to another section of this chapter if replacement of a particular assembly or part is necessary. The tables include: Chromatographic problems Temperature readout problems Pressure readout problems Fuse problems Output problems Electric problems Communication problems 70

77 Troubleshooting Troubleshooting Table 8 Chromatographic Problems Problem Assembly/part Comments Poor separation Column Some separation problems are corrected by conditioning the column. See Chapter 5. Water in sample. Damaged column. Operational parameters Check that the column temperature and head pressure are suitable for the analysis. Varying peak heights Sample transfer lines Check for loose connections and leaks. Do not use Snoop. Vacuum pump See "No vacuum/low vacuum" problems. Injector Call Agilent Technologies. Ghost peaks Column contamination Conditions the column to eliminate residues from prior injections. Sample with a 30 second sample time to clean all transfer lines. Increase run time between injections to avoid carryover in subsequent run. Sample inlet and manifold assembly Check for leaks at the transfer lines. Check for leaks at manifold assembly entry. Negative peaks Carrier gas Refill internal carrier gas tank after purging at leat 3 times. Noisy baseline Environment Check for mechanical vibrations or heavy fluctuations in ambient pressure. Detector Check if problem exists in both modules. Control PCB board Replace control board as outlined in Chapter 7. Low sensitivity Control PCB Check carrier gas setting. When the PCB switches are set for argon, sensitivity is decreased. Vacuum pump Check pneumatic problems Table 11. Sample inlet frits Check external sample inlet frits for plugging Module connecting tubes Check O rings and replace if necessary. Injector Possible plugged. Need to send module or instrument to Agilent Technologies for repair. 71

78 Troubleshooting Troubleshooting Table 9 Temperature Readout Problems Problem Assembly/part Comments Temperature Display Make sure you are monitoring the correct channel. readout is different than setting Heater Check that the heater cable is properly seated on its connector. Memory Reset memory of EPROM. Update CT scale. Control PCB Replace control PCB. Table 10 Pressure Readout Problems Problem Assembly/part Comments Pressure readings are erratic Display Make sure you are monitoring the correct channel. or wrong Pressure transducer assembly Check that the pressure cable is properly seated on its connector. Parameters Reset the memory chip and reenter the CHP system configuration values. Make sure carrier is off for at least 5 minutes. Control PCB Faulty board. Replace control PCB. 72

79 Troubleshooting Troubleshooting Table 11 Table 12 Pneumatic Problems Problem Assembly/part Comments No vacuum/low vacuum Parameters Make sure the sample time is at least 5 seconds. Vaccum pump Check connections. Replace vacuum pump. Control PCB Replace control PCB. Sample inlet Check inlet line filter frit. It may be plugged. Injector Send unit to Agilent Technologies for repair. Leaks-high helium usage- low Solenoid valves Check for leaks at solenoid valves. sensitivity Connections Check for leaks at carrier gas connections. Do not use Snoop or any liquid to check for leaks. Pressure transducer Check to ensure that the pressure transducer "O-ring" has not become unseated. Sample transfer lines Check the fitting connections for all sample transfer and connection lines Fuse Problems Problem Assembly/part Comments Fuses burned out Control PCB connectors Check to make sure the cables are inserted correctly and are not offset EPROM If new EPROMs have been installed, check that they are properly seated and that no pins are bent. Control PCB Ensure that the control PCB is properly mounted and is not touching the top of the modules. Check valves Check the 1800 psi inlet line. If the check valve is faulty, carrier gas with leak out of the inlet line. Sample transfer lines Check the fitting connections for all samples. Power switch LED does not come on after charging battery Battery charger Measure the battery charger output. The cahrger should be volts under load. Fuses Interconnections Check the 3 amp fuse on the power circuit PCB. Check the 3 amp fuse which is part of the power cable assembly. Ensure that all cables which are connected to the control PCB and power circuit PCB are properly seated. 73

80 Troubleshooting Troubleshooting Table 13 Output Problems Problem Assembly/part Comments No output-auto zero out of specs Detector The autozero specification is less than 420 millivolts. Detector may need to be replaced it out of spec. Range. Check the instrument setup screen to make sure the detector filamants are on for the channel you are monitoring. Rear panel Check to ensure that the 5 Luer lock connectors have been removed. Optional carrier gas If you are using argon or nitrogen as the carrier gas, check the switch settings on the control PCB. Connections Make sure all cables are properly seated at the PCB control board. Sample inlet Make sure the inlet frit or the sample transfer lines are not plugged. Control PCB Check that all connectors at the control PCB are properly inserted and fully seated. Replace control PCB as described in Chapter 7. Vacuum pump Check that the vacuum pump is set with a sampling time of at least 5 seconds. EPROM Power off and on. Confirm temperature reading. If temperature is wrong, see Readout problems in Table 9. Table 14 Electric Problems Problem Assembly/part Comments P200 power P200 battery With the GC turned off and the battery charger disconnected, measure the voltage between the fuse on the power circuit PCB and pin 4 switch does not function of the DIN power connector. If the voltage is less than 10.5 volts, recharge the battery overnight. If the battery is not rechargeable, replace it. 74

81 Troubleshooting Assembly/ parts replacement Table 15 Communication Problems Problem Assembly/part Comments No communications with comrectly installed. Software Make sure the computer is properly configured and software is corputer Check communication port interrupt (IRQ) conflicts in the computer BIOS. Computer Check serial cable connections. Press <Esc> if EZChrom is hung up. Connections of serial Check serial cable connections. cable Replace the serial cable. Control PCB board Ensure the cable is pin to pin straight-through type cable. Replace control PCB board. Assembly/ parts replacement The P200/ P200H is a modular system consisting of easy to assemble and disassemble modules and assemblies. Because of the modularity and small size of the silicon components, the most expedient way to repair an instrument is to exchange assemblies and/or modules. This section details the replacement of the main components of your P200/ P200H. Replacing the controller board of the P200 Tools required: Blade screwdriver Phillips screwdriver 1/4 inch open end wrench or nut driver All functions of the system are routed to the controller board. Pressure and temperature signals, power control to the sampling pump and to the heaters, as well as detector signals originate or are processed by the controller board. The Serial I/O port on the board takes the method parameters and sends them to the microprocessor where they are translated and routed to the proper device. 75

82 Troubleshooting Assembly/ parts replacement To replace the controller board do the following: 1. Turn the power switch off on the front of the P200. WARNING During this process you will expose the internal components and voltages of the unit. To avoid damaging the unit, disconnect all external power to the unit and turn the power switch off. 2. Disconnect all cables from the back of the P200 (RS-232 cable, the Analog Control Cable and the 12 VDC power supply cable). 3. With a Phillips head screwdriver, remove the four screws that are on the side of the top cover. Lift and remove the top cover. Top cover screws Top cover screws ON H OFF GAS SAMPLE ONL CAUTION: SAMPLE INLET(S) HOT CARRIER CARRIER POWER SERIAL P Series Figure 30 Top cover screws Locate and record the scale and offset values that are written on the label on the metal aluminum cover near the front of the unit on the new controller board. Locate and record the column heater and offset values that are found on each of the module labels. These numbers may be used to set your unit configuration in the future. 4. Lifting the cables straight up, remove all connectors between the controller board and the chassis tray. 5. Disconnect the RS232 Cable at the J20 position in the controller board. This cable comes from the front panel of your P200 and provides the second I/O port. 76

83 Troubleshooting Assembly/ parts replacement 6. Disconnect the battery cable. This is the cable that plugs into the small orange connector, at position J19 and is next to the 12 VDC plug. 7. Using a 1/4 inch open end wrench or nut driver, remove the two nuts that secure the board to the metal standoffs that are fastened to the bottom of the frame. 8. Lift and remove the controller board at a slight angle to clear the sides and free the back connectors from the back panel. Set the old controller board aside, making sure the underside is face up to protect the circuitry. 9. Remove the new board from its protective wrappings. Place the new controller board in the location occupied by the old one by reversing the disassembly steps. 10. Continue with "Resetting the instrument configuration". Resetting the instrument configuration To reset the instrument configuration parameters, do the following: 1. Connect power and serial cables. Do not connect carrier gas. 2. Follow the instructions in Chapter 3 for "Verifying Installation". 3. A window should appear indicating an error condition. Click [OK] and Verification Confirms that there are problems. Figure 31 Checking for error conditions 77

84 Troubleshooting Assembly/ parts replacement Since you want a functioning GC, click Yes. The next window advises you that the GC has forgotten its name (serial number). Figure 32 Instrument ID Type in the serial number (which is on a sticker on the back of the GC and click [OK]. If you have typed in the serial number correctly, GC Verification will restore its configuration. Figure 33 Status After the configuration is restored, you have to cycle the GC s power. GC Verification walks you through this process. First you will have to turn the GC OFF. 78

85 Troubleshooting Assembly/ parts replacement Figure 34 Cycle GC power I Unplug the GC first and then click the [OK] button. Now you need to turn the GC back ON. Figure 35 Cycle GC power II Plug the GC back in and then click the [OK] button. Because of the way certain options are implemented, it will probably be necessary to cycle the power again. GC Verification will know if this is the case and, if so it will ask you to turn the GC OFF and then back ON again. When the sequence is done, you will see the following window: 79

86 Troubleshooting Assembly/ parts replacement Figure 36 Cycle GC power III Click [OK], reconnect carrier gas. Resetting column head pressure (CHP) values If there were problems with memory that might have compromised the column head pressure (CHP) offset data stored in the memory, you see the following window. 80

87 Troubleshooting Assembly/ parts replacement Figure 37 Resetting CHP offset I Disconnect the helium carrier from the back of the GC and then click the [OK] button. GC Verification will repeatedly send a command to set the CHP to zero and then check that the CHP actually is 0 unti lthat is the case. Each time through this process, the number of retries is incremented. The process should be complete within retries, if it goes longer, there may be a problem with the carrier gas plumbing. If the number of retries becomes excessive (more than 10 or so), click Cancel and call Agilent Technical Support. If the CHP reset is successful, the window will display: 81

88 Troubleshooting Assembly/ parts replacement Figure 38 Resetting CHP offset II Click [OK] to continue. Usually this will fix any problems and you will see the GC Verification Successful window. Figure 39 GC verification Replacing a P200 module Tools required: Blade screwdriver 1/4 inch open end wrench nut driver 82

89 Troubleshooting Assembly/ parts replacement 7/16 inch open end wrench Needle nose pliers Low flow rate flow meter (option) Phillips Screwdriver 5/16 inch open end wrench 9/64 inch hex driver/ module tool Helium leak detector (optional) The two GC modules can be replaced individually. To begin you will need to do the following: WARNING During this process you will expose the internal components and voltages of the unit. To avoid damaging the unit, disconnect all external power to the unit and turn the power switch off. 1. Remove any nuts or fittings from sample inlet connection at front of unit. 2. Remove Carrier gas connections. 3. Remove the top cover from the instrument by removing the four Phillips head screws on the top cover (Figure 30). 83

90 Troubleshooting Assembly/ parts replacement Back panel screws ANALOG/CONTROL SERIAL I/O AUX 12VDC IN A & B RS-232 POWER 12VDC COL A VENT SAMPLE VENT COL B VENT CARRIER FILL 1800 PSI MAX CARRIER OUT REF A VENT CARRIER IN REF B VENT COLUMN A PRESSURE COLUMN B PRESSURE H Figure 40 Back panel connections Carrier gas transfer tube Back panel screws 4. Remove the power and data cable connectors and the ground lug connected to the PCB mounting screws. 5. Remove the four screws located inside back panel feet (Figure 40). 6. Carefully remove the entire module/ chassis assembly from the case by sliding the assembly out the rear of the case. (See Module removal on page 88). Take care that the front panel cable does not interfere with the removal of the assembly. Set the case aside. 7. Remove the controller board from the module/ chassis assembly. a. Remove all electrical connections between the controller board and the chassis assembly. b. Remove two nuts and one remaining screw with the 1/4 inch wrench and Phillips screwdriver. Remove controller board and set aside. 8. Disconnect the plastic tubing from the module by removing the Luer-lock fittings. Fold these tubes out of the way. 84

91 Troubleshooting Assembly/ parts replacement 9. With the module tool (stored inside instrument) or a 9/64 inch hex driver, loosen the two cap screws that secure the injector tubes to the manifold block approximately one full turn. Do not remove these screws. 10. Turn the chassis assembly on its side and remove the module mounting screws from the module which is to be replaced. Return the chassis assembly to its right-side-up orientation. 11. Remove the module and set aside. For long term storage, it is advisable to store the GC module with the Luerlock caps installed on the column vents and the injector tubes sealed with non-coring septum. This will protect the internals of the system from oxygen and water. 12. Carefully insert the replacement module tubes into the matching positions of the manifold block openings. The sample tube (lower right) will butt against the back of its passage; the four tubes should move freely fore and aft. A pair of needle nose pliers will help greatly in this operation. 85

92 Troubleshooting Assembly/ parts replacement Module Pressure control manifold Nut screws Fastening screws Vents Figure 41 Module connections Lines to manifold A pair of needle nose pliers will help greatly in this operation. 13. Turn the chassis on the side of the replacement module. This will help support the module. Replace the two mounting screws. 14. Turn the chassis upright. Using the module tool or a 9/64 inch hex driver, tighten the two cap screws to secure the five injector tubes. Return the module tool to its holder for future use. 15. Connect the unit to a source of 80 psi of helium carrier gas and leak check the manifold tube connections using a mass specific of hand held leak detector. Do not use liquid leak detectors! If leaks are detected at the tube connections, tighten the appropriate screws until no leak is detected. 16. If available, connect a flow meter to the sample and reference exhaust ports to verify proper flow. At 20 psi carrier pressure, capillary columns should 86

93 Troubleshooting Assembly/ parts replacement flow approximately ml/ min and PLOT columns approximately ml/ min. If no or low flow is detected out of the module exhaust ports a plug is indicated in the bottom left module tube and the connection should be redone after checking the end of the tube for particles. 17. Reassemble the unit. a. Put the controller board back in to place and fasten using the two screws and nuts. Do not install screw closest to the power connector. Redo all electrical connections making sure to check that the cable connections are lined up correctly with the PCB connector base. It is quite easy to inadvertently hook up the electrical connectors so that they are offset to one side or the other. b. Carefully slide the chassis assembly back into the case making sure that the edges of the chassis plate are lined up with the plastic slides in the case. Slide the chassis into the cases until the back panel is approximately one from the case bezel. Secure the P200 data cable ground lead with the remaining controller board mounting screw at this time. Continue sliding the chassis assembly into the case until the sample inlet fitting is protruding through the front panel and the back panel is resting against the case. c. Install the four back panel screws and the carrier gas transfer tube. d. Connect the power and data cables into place on the controller board. e. Before putting on the cover, make a note of the column heater offset and scale factors which are written on the module label located on top of the module. 18. Please follow the instructions for Verifying installation on page Operate instrument to verify normal operation. 20. Replace instrument cover and secure with the four black case screws. 87

94 Troubleshooting Assembly/ parts replacement Replacing a P200H module Tools required: See replacing P200 module The sample transfer lines are thin-walled and fragile. Sharp bends may break the sample transfer line. Removal and installation of the GC module involves handling of the sample transfer lines. In particular, the installation of the sample transfer lines into the sample inlet fitting housing requires special care. Module removal These instructions would be inserted between Item 6 and Item 7 in the P200 Service Instructions (see page 84). a. Find the sample inlet fitting housing, located on the backside of the front panel. The sample transfer lines run from the sample inlet fitting housing to the top of the GC modules. Find the six-conductor cable which connects the sample inlet fitting housing to the printed circuit board on the backside of the front panel. Disconnect the cable from the printed circuit board on the backside of the front panel. Use a medium size straight-blade screwdriver to pry the locking tab on the cable connector and free the connector from the socket on the printed circuit board. b. Carefully pull the 1 inch diameter yellow foam thermal insulation (or remove the yellow foam insulation) and the 1/8 inch diameter white sleeve away from the sample inlet fitting housing, thereby exposing about 3/4 inch of the metal sample transfer lines. c. Carefully pull the sample inlet fitting housing away from the back of the front panel, sliding the fitting housing along the sample transfer lines, thereby exposing the nut which holds the sample transfer lines onto the 1/16 inch Swagelok bulkhead union which is the GC sample inlet. Loosen the nut with a 5/16 inch wrench. d. Carefully detach the nut and the sample transfer lines from the bulkhead union. Carefully remove the ferrule from the ends of the sample transfer lines (Save the ferrule for possible reuse). Remove the nut from the ends of the sample transfer lines. 88

95 Troubleshooting Assembly/ parts replacement e. Carefully slide the sample inlet fitting housing off the ends of the sample transfer lines. P200H module replacement II These instructions should be inserted between Item 16 and Item17 in the P200 Module Replacement instructions (page 86). a. Pull the white sleeve and the yellow foam insulation away from the ends of the sample transfer lines, thereby exposing about 3/4 inch of the ends of the metal sample transfer lines. b. Find the sample inlet fitting housing. That there is an eight-hole TEKA connector on the printed circuit board of the sample inlet fitting housing. The middle four holes are active and equivalent (each is electrically connected to chassis ground). Align the sample inlet fitting housing so that the cable will be located for easy reconnection to the printed circuit board on the backside of the front panel. Carefully insert the end of each sample transfer line into one of the middle four holes (of the eight holes) of the TEKA electrical connector on the PCB of the sample inlet fitting housing. c. Carefully slide the sample inlet fitting housing onto the sample transfer lines, thereby compressing the white sleeve and the yellow foam insulation. Pull the metal sample transfer lines and push the sample inlet fitting housing until the ends of the metal sample transfer lines protrude about 3/4 inch from the other side of the sample inlet fitting housing. d. Slide the ends of sample transfer lines into the nut. e. Carefully slide the ends of the sample transfer lines through the ferrule. Slide the ferrule onto the sample transfer lines so that the ends of the transfer line extend about 1/16 inch beyond the ferrule. f. Carefully insert the ends of the sample transfer lines into the 1/16 inch Swagelok bulkhead union sample inlet, at the backside of the front 89

96 Troubleshooting Assembly/ parts replacement panel. Using a finger or a 5/16 inch wrench, tighten the nut onto the bulkhead union, thereby securing the ends of the sample transfer lines onto the bulkhead union. Tighten the nut about 1/2 to 1 turn beyond finger tight, or as required to obtain a leak-tight connection. If possible, check this connection for leaks. Connect 30 psi helium to the GC inlet and check for a leak at this connection. g. Carefully slide the sample inlet fitting housing over the bulkhead union. Some rotation of the housing may be require to align the hexagonal flats on the nut with hexagonal core of the sample inlet heater. The housing should fit closely against the backside of the front panel (the gap should be less than 1/16 inch). h. Adjust the white sleeve on each sample transfer line, so that the sleeve presses against the TEKA connector. The white sleeve should completely cover the metal sample transfer line and no metal sample transfer line should be exposed. i. Install or adjust the yellow foam thermal insulation, so that the sample transfer line is completed enclosed from the top of the GC module to the sample inlet fitting housing printed circuit board. j. Reconnect the cable from the sample inlet fitting housing printed circuit board to the printed circuit board on the backside of the front panel. Replacing the P200/ P200H solenoid valves Tools required: Standard blade screwdriver 1/4 inch open end wrench or nut driver 1/16 inch Allen wrench Phillips screwdriver Heavy needle (or any instrument with a fine point.) The solenoid valves are seated at the top of the controller blocks. Each valve is secured to the controller block with two screws. The electrical leads come from 90

97 Troubleshooting Assembly/ parts replacement the top of the solenoid valve and travel towards the controller board through cables that are shrink wrapped (Figure 42). The cable ends on a connector housing that mates into the P200 controller board. To replace any of the solenoid valves, do the following: WARNING During this process you will expose the internal components and voltages of the unit. To avoid damaging the unit, disconnect all external power to the unit and turn the power switch off. 1. Remove the controller board using the steps given on page Using the 1/16 inch Allen wrench, remove the two screws that fasten the solenoid valve to the controller block. To other solenoid valves Shrink wrap cable Locking barbs Allen screw heads Connector housing Solenoid body Figure 42 Solenoid connections 3. First identify the two leads coming from the solenoid you are replacing at the connector housing. 4. Using a needle or a very narrow blade screwdriver, depress the locking barbs at the connector housing for the two wires and pull the leads out. Record the location and color of each wire at the connector housing so that the new solenoid connections are made exactly the same. 91

98 Troubleshooting Assembly/ parts replacement 5. Pull the leads through the shrink wrap to free the solenoid from the cable harness. Set the free solenoid aside. 6. Thread the leads of the new solenoid through the shrink wrap and connect the end leads to the connector housing. Make sure wires are at the correct locations and are properly inserted. 7. Inspect the solenoid gaskets mating surfaces for dust and contaminants. Clean if necessary. Seat the valve and replace the two Allen screws. Caution Do not exceed three inch/pound torque as higher force may strip the threads off and/or distort the body of the solenoid valve. 8. Reassemble the unit, replacing the controller board and reinserting the entire assembly into the P200 case. Follow all instructions given on prior sections when replacing and testing the installation of any new assembly or part. Replacing the P200/ P200H sampling pump Tools required: Standard blade screwdriver 1/4 inch open end wrench or nut driver Phillips screwdriver Precision Phillips screwdriver The P200 sampling pump is located to the right of the "channel A" pressure controller. The sampling pump uses the vacuum to draw the sample into the injector loop on command of the microprocessor and for a duration specified in the method. 92

99 Troubleshooting Assembly/ parts replacement WARNING During the removal of the sampling pump you will have to remove the unit s top cover and expose the internal components and voltages of the unit. To avoid damaging the unit, disconnect all external power to the unit and turn the P200 front power switch off. 1. Remove the P200 Controller board. Follow the instructions given on page Pull the vacuum lines from the body of the vacuum pump. One line goes to the pressure controllers. The second line goes to the rear vent. 3. Disconnect the electrical lines from the top of the vacuum pump solenoid. 4. Turn the assembly on its side to get a clear view of the bottom plate and locate the two Phillips screws that secure the vacuum pump to the bottom plate of the assembly. 5. While holding the vacuum pump, use a Phillip s head screwdriver to remove the two screws. 6. Replace the vacuum pump by reversing the steps used to remove the assembly. When reinstalling the P200 controller board, read the instructions given for replacing this board. Pay special attention to the electrical connections. Replacing the P200 battery Tools required: Standard blade screwdriver (2) 1/2 inch open end wrench Phillips screwdriver To replace the battery, do the following 93

100 MADE IN U.S.A. Troubleshooting Assembly/ parts replacement WARNING During the removal of the battery you will have to remove the units top cover and expose the internal components and voltages of the unit. Secondly, you must disconnect the carrier jumper line. To avoid damaging the unit, disconnect all external power to the unit and turn the P200 front power switch off. Turn the carrier gas off. 1. Remove the top cover of your P200 (see Figure 30). 2. Place the unit with the back panel facing you. 3. Remove the four slotted screws located in the outside perimeter of the left panel (Figure 43). Right back panel Slotted screws HMODEL: SERIAL NO.: COL. A: COL B: Carrier gas jumper line Battery Slotted screws Figure 43 Battery compartment 4. Loosen and remove the jam nuts securing the carrier jumper line. 5. Grab hold of the rightmost rear foot and pull the small rear panel off the P200 chassis. 6. The battery case will now be visible. Remove the battery carefully so not to scratch or damage the battery terminals. 7. Disconnectthe red and blackwires from the old battery and install them on the new unit. Make sure the redwire is connected to the negative terminal ( ) on the battery. 94

101 Troubleshooting Assembly/ parts replacement 8. Slide the battery into the unit. Be careful not to pinch the battery leads as you insert the battery. 9. Reattach the small rear panel to the unit, replace the jumper tube. Use the EZChrom instrument status window to determine the charge on your new battery. Replacing the P200H battery Tools required: Phillips screwdriver To replace the battery, do the following: 1. Turn the carrier gas off and turn off power. 2. Flip the unit over and set it down on its top cover. 3. Remove all 4 Phillips screws holding the bottom cover, remove the cover. 4. Facing the front panel of the unit, on the right side you will see the battery compartment. The panel covering the compartment is held by a single Phillips screw on the right edge of the panel. Remove this screw. Remove the panel. 5. Remove the battery and disconnect the terminal leads connected at each end. 6. Notice on either end of the new battery are "+" and "_" signs. Reattach the red terminal lead to the "+" end and the black terminal lead to the "_" end. 7. Place the new battery into the battery compartment. 8. Replace the compartment and bottom panels by reversing the initial steps. 95

102 Troubleshooting Assembly/ parts replacement 96

103 Glossary

104 Glossary For your convenience, this section gives an alphabetical listing of the technical terminology used in this manual. A-B Analog to digital converter (ADC): A device that takes the analog inputs and translates them to digital form so that they can be processed by a computer. Baking out: Running your P200/ P200H Column ovens at very high temperature to elute impurities from the column. Same as "column conditioning" this procedure is also called "column conditioning". C Carrier: A pressurized gas that pushes the sample through the column. The carrier also known as the mobile phase in a gas chromatography separation, should be dry, pure and inert. Chromatography: A technique used to separate sample mixtures based on the different affinity of compounds to a stationary phase. Chromatogram: A plot of the detector response versus time. Column: The component of a chromatograph where separation occurs. Column conditioning: An operation that removes traces of moisture and strongly adhered components of a column that do not elute under the normal operating conditions from a column. This procedure is also called "baking out". Column dead time: The time it takes for an unretained compound to elute from a column. Column head pressure: An instrument parameter that controls the carrier flow and therefore affects the retention time of all peaks in a chromatographic run. 98

105 Glossary Column head pressure offset (CHP offset): A calibration factor that is experimentally determined for each pressure transducer. This value in the system configuration permits correct determination of the column head pressure. Column head pressure scale (CHP scale): A calibration factor that is experimentally determined for each pressure transducer. This value in the system configuration permits correct determination of the column head pressure. Column temperature: Parameter that affects the retention time and separation of all peaks in a chromatographic run. Column temperature offset (CT offset): A calibration factor that is experimentally determined for each temperature sensor. This value when entered into the system configuration permits correct determination of the module temperature. Column temperature scale (CT scale): A calibration factor that is experimentally determined for each temperature sensor. This value when entered into the system configuration permits correct determination of the module temperature. Configuration: The designation of an analyzer and /or modules that are attached to a computer. It also permits the resetting of the column head pressure offset and column upper temperature protection limits. D Data acquisition: The phase of data handling that begins with the sensing of the detector signal and ends with recording of raw data (chromatograms). Data output: The data generated by the acquisition system. Data reduction: The process of ordering, classifying, sorting and summarizing data that results in the conversion of the data bunches into areas. Data system: Devices that generate qualitative and quantitative information by comparing chromatograms of standards and samples. 99

106 Glossary Defaults: Parameters that automatically appear upon initial setup. Detection system: The part of a gas chromatograph that senses the elution of the components from the column. E Equilibration time: The time required for a system to stabilize both chemically and thermally. Elution: A component is injected into a column to pass through the detector. Erasable programmable read only memory (EPROM): Computer chips that contain program information. External standard: A calculation that compares (column head pressure, temperature and detector sensitivity) the area of a peak in sample to the area of the same peak in calibration gas analysis. F Flow meter: A device that provides adjustment and a visual indication of flow. Function keys: Keys in the computer keyboard that may be used as shortcuts to implement commands in a pulldown menu. G Gas chromatography (GC): An analytical quantitative and qualitative technique that separates the components in a gas mixture by passing them with the aid of a carrier gas over column packing/ coating. Depending on the stationary phase (column packing/ coating) gas chromatography can either be Gas Liquid Chromatography or Gas Solid Chromatography. Gas solid chromatography (GSC): An analytical quantitative and qualitative technique that separates the components in a gas mixture by passing them with the aid of a carrier gas over a column packed/ coated with an absorbent material, such as MSSA. 100

107 Glossary Gas liquid chromatography (GLC): An analytical quantitative and qualitative technique that separates the components in a gas mixture by passing them with the aid of a carrier gas over a column coated with a chemically bonded liquid phase, such as OV-1. H-M Injector: A micromachined device used by the Agilent analyzers to introduce a precise volume of sample into the column. Method/ instrument parameters: A set of instrument parameters that control the operation of your system; the peak detection and identification settings, the response factors and the peak calibration areas (Everything listed under the Method menu in EZChrom 200). Molecular sieve: Synthetic zeolites, rigid column packing material used to separate compounds in GC based in their molecular size and structure. N-P Normalization: A process that reports the corrected area (per channel) of a peak to the total of the corrected areas of all peaks in an analysis. Corrected areas have taken into account variations in detector response due to selectivity of a detector. Peak concentrations (mole fractions) are rounded to four places pass the decimal point. Pressure: An operational parameter that affects the elution time of the peaks in an analysis (See column head pressure.) Q-R Qualitative analysis: Calculation of concentrations done by relating the detector response (areas or heights) of a standard sample, to those of a sample that is run under exactly the same analysis conditions. Random access memory (RAM): Computer memory that can be erased and rewritten. This type of memory holds all method files, data files and reports. 101

108 Glossary Raw data: Unprocessed chromatograms consisting of data points transmitted by the P200 to a data system for processing. Response factor: A number that relates the detector response (area or height) of a peak to its concentration in a calibration standard. Retention time: The time from the moment of injection to the apex of a peak in a chromatogram. Retention times are measured in seconds. The retention time of a peak is affected by column head pressure and temperature. S Selectivity: A property of a column that results in the separation of two substances as they elute from a column under specific conditions. Serial port: A connector that carries or receives information from one device. In the P200, the serial port receives the method conditions from a computer and sends data and status information. Sensitivity: A detector setting that gives a larger response to a substance (other factors being equal) and a better signal-to-noise ratio. High sensitivity provides precise analysis of very low sample concentrations. Standard: A calibration gas with known composition and concentration that you can use to determine response factors for sample gases. Stationary phase: The immobile phase (column packing or coating) in the chromatographic separation process. T-Z Thermal conductivity: The ability of a substance to conduct heat from a warmer to a cooler surface. Helium is chosen as a carrier gas because of its high thermal conductivity value versus most sample components. Test chromatogram: A chromatogram from the instrument manufacturer that shows the separation of a particular sample under a specific set of conditions. 102

109 Glossary Thermal conductivity detector: A solid state detector in the Agilent gas analyzers that measures the difference in resistance on two branches of a Wheatstone bridge. The TCD output generates a chromatogram. Troubleshooting: A systematic approach that results in fault isolation and correction of an operational or hardware problem. Wheatstone bridge: A device for measuring electrical resistances, that consists of a conductor joining two branches of a circuit. This bridge is the basics of the SSD. 103

110 Glossary 104

111 Appendix A TCD Schematic and Nominal Resistance Values

112 TCD Schematic and Nominal Resistance Values This appendix describes some of the component calibration and specifications for parts in different assemblies of the P200. In addition, two power schematics are provided As discussed in Chapter 6 of this manual, the micro universal Solid State Detector (SSD) is based on a Wheatstone Bridge where two branches of a circuit are joined to compare resistance. When pure carrier gas passes through both branches of the bridge, the cooling effect on the filaments is the same and the bridge, which was initially balanced, will stay balanced. When a component elutes from the column and touches one set of filaments, the cooling effect on the on one set of filaments will change. With the change in temperature the resistance of the filaments will change and the bridge will become unbalanced. The bridge will become balanced again when pure carrier gas passes again through the filaments. Figure 44 is an schematic of the P200/ P200H SSD. Reference flow R1 S1 Sample flow S1 R1 Pin 1 Pin 3 Pin 4 Pin 2 Signal Supply voltage Figure 44 Solid state detector circuitry Our schematic shows the four matched filaments (R1, R1, S1, and S1). Two of those filaments are exposed to the flow coming from the sample column, and 106

113 TCD Schematic and Nominal Resistance Values two are exposed to the flow coming from the reference column. Pin 1 and Pin 3 bring out the detector signal, while Pin 4 and 2 bring in the regulated power supply voltage to the filaments. Controller board J9 J Cable connectors Ribbon cable Figure 45 Detector connector pin assignments Table 16 Nominal Detector Resistance Values Measured between Nominal value Comments Pin 1 and 3 Pin 2 and 4 Pin 1 and 2 Pin 2 and 3 Pin 3 and 4 Pin 4 and These readings should be within 5 ohms of each other. Values higher than 400 ohms indicate a damaged or broken bridge Figure 45 shows the location of those pin assignments in the ribbon cable connector that mates at the controller board. Table 16 shows the nominal resistance readings and the tolerance limits of the filaments as their resistance is read with an ohmeter. The detector filaments for both Channel A and B should have filament resistance values that are very close to each other so that the bridge can be balanced. 107

114 TCD Schematic and Nominal Resistance Values Resistance readings of heater/sensor elements Resistance readings of heater/sensor elements Each channel module contains a heating/sensor system that sets and regulates the temperature of the encapsulated components in each module. A ribbon cable that connects at the controller board carries the output signals and the power to the elements. As in the case of the pressure transducer, the heating elements must be calibrated to obtain a correct temperature reading. The calibration will generate a column temperature offset and a column temperature scale factor. Both of these numbers need to be entered in the system configuration for a particular instrument and are unique for each module. The factory calibration factors are written on a label that is affixed to each module. When a heating or sensor pin is damaged, you can easily determine it by measuring the resistance at the connector in the ribbon cable that mates at terminals J11 and J4 of the controller board (Figure 46) GND Sensor Heater Red lead Figure 46 Heater/Sensor connector pin assignments 108

115 TCD Schematic and Nominal Resistance Values Resistance readings of heater/sensor elements Table 17 Nominal Heater/Sensor Resistance Values Contacts Reading Comments Pin 2 and ohms See column sensor calibration Pin 4 and 5 Pin 2 and 4 Pin 3 and 4 Pin 2 and 5 Pin 3 and 5 Pin 1 and 2 Pin 1 and 3 Pin 1 and 4 Pin 1 and 5 24 ± 3 ohms All these pairs should read infinity Figure 47 Power hookup schematic 109

116 TCD Schematic and Nominal Resistance Values Resistance readings of heater/sensor elements Figure 48 Power protection circuit schematic 110

117 TCD Schematic and Nominal Resistance Values Single channel P200 Single channel P200 If you would like to change your dual channel unit to a single channel unit, you can remove one channel and reestablishing the system configuration through the EZChrom software. It is necessary to add a "heater dummy " and a "transducer dummy" plugin circuit to the controller board at the locations normally occupied by the corresponding ribbon cables. A schematic of both of these circuits is shown in Figure 49 and Figure approx J4 (A-Side) J11(B-Side) 499 ohms, 1% Pin approx Side view 5 Pin Molex connector Figure 49 Heater dummy circuit p/n CON

118 TCD Schematic and Nominal Resistance Values Single channel P200 Solder 4.99K ohms, 1% 0.10 approx 4.99K ohms, 1% J6(A-Side) J13(B-Side) Pin approx Side view 4 Pin Molex Connector Figure 50 Tranducer dummy circuit p/n CON-2104 Table 18 Recommended Spares Description Part number Comments P200 charger (USA) PWR 1355 Recharges 12 V battery, while supporting a amximum load of 1A. Input 115 V ± 10% Hz. P200 charger (International) PWR 1459 Vacuum pump PMP 1659 Flow rate > 0.3 L/min. Valve solenoid VLV 1191 Normally open Valve solenoid VLV 1192 Normally closed Pressure transducer PCB Pressure range 70 psi Recharges 12 V battery, while supporting a maximum load of 1A. Input 230 V ± 10% Hz. 112

119 TCD Schematic and Nominal Resistance Values Single channel P200 Table 19 Accessories Description Part number Comments Carrying case for M200 and P200 and accessories General purpose integrator cable Integrator cable for SP4400 and SP4270 Multipurpose analog/contact closure control (P200) Auxiliary power cable adapter External sample filter kit CAS 1343 CBL 2019 CBL 2188 CBL 2048 CBL 2131 (Spade lugs) Cable DB 15 to terminal block For vehicles cigarette lighter KIT Complete unit, cartidge, ferrules and 5 10 um filters Replacement filters KIT 2170 For use with external sample filter kit (5 10 micron filters Sample flow controller PNU 2103 Constant sample bypass flow unit max inlet pressure 1000 psi Gas filter assembly PNU 2058 For refilling P200 internal tank Welker sample conditioning system Spare GC modules PNU 2105 MOD XXXX Replace XXXX with last fourdigits of column option (see Chapter 4) Filter and flow controller Module exchange accessory kit (QA00,QB00, or QABO required in instrument 113

120 TCD Schematic and Nominal Resistance Values Single channel P200 Table 20 Sampling from Dispoable Syringe (Kit 2021) Item Description Quantity 1 60 cc Disposable syringe mm Syringe tip filter 30 3 Miniature syringe valve 1 4 1/16 inch SS needle, blunt 2 inch 1 5 1/16 inch Swagelok nut and ferrule 1 6 Syringe support bracket 1 Table 21 Sampling from Reusable Syringe (Kit 2022) Item Description Quantity 1 30 cc Micro mate glass syringe mm Syringe tip filter 30 3 Miniature syringe valve 1 4 1/16 inch SS needle, blunt 2 inch 1 5 1/16 inch Swagelok nut and ferrule 1 6 Syringe support bracket 1 114

121 TCD Schematic and Nominal Resistance Values Single channel P200 Table 22 Sampling from Tedlar bag (Kit 2023) Item Description Quantity 1 1 liter tedlar bag SS 10 2 SS sampling tube, inch 12 inch 3 3 1/16 inch Swagelok nut and ferrule 3 4 Ferrule, 1 hole 0.5 mm DIA 1/16 inch 10 Table 23 Sampling from VOV Vial Kit 4 (Kit 2024) Item Description Quantity 1 40 ml vial, silicone septa 72 2 SS sampling tube, inch 12 inch 3 3 1/16 inch Swagelok nut and ferrule 3 4 Ferrule, 1 hole 0.5 mm DIA 1/16 inch 10 Table 24 Sampling from High Pressure Source (Kit 2025) Item Description Quantity 1 Sampling conditioning system 1 2 Flow controller 1 115

122 TCD Schematic and Nominal Resistance Values Single channel P

123 Appendix B Quad-Series Micro Gas Chromatograph

124 Quad-Series Micro Gas Chromatograph Introduction This document is intended as a supplemental User s Manual for the operation of the Quad-Series Micro Gas Chromatograph (GC). It serves as an addendum to the P200/P200H Micro Gas Chromatograph User s Manual that has been shipped with your Quad-Series instrument. This document describes the basic functional and operational differences between the Quad-Series instrument and that described in the accompanying P200/P200H manual. Although the differ-ences between these two instruments are minor and thus do not necessitate a separate manual, they are documented here for clarification in the operation of this Quad instrument. Items not discussed in this addendum regarding the Quad-Series GCs can be found in the P200 Micro Gas Chromatograph User s Manual. The differences in the EZChrom 200 and EZChrom 400 Chromatography Data Systems are documented in the Introduction Section of the EZChrom Chromatography Data System User s Manual. Please refer to this manual for a description of the software differences. Quad-Series Micro Gas Chromatographs Your new Quad-Series Micro GC is quite simple and closely parallels the operation of the P200 Gas Chromatograph, whose User s Manual is included with your instrument. The fundamental differences between the two instruments are the available number of modules (i.e., independent gas chromatographs), the number of sample inlets, and the number of carrier gas inlets. The Quad-Series micro GC can be configured with two to four modules, one to four sample inlets, and one to two carrier gas inlets. These operational differences are better understood by viewing the front and rear panels of the Quad-Series Micro GC. 118

125 Quad-Series Micro Gas Chromatograph Quad-Series Micro Gas Chromatographs It should be noted that Agilent Technologies offers two versions of the Quad- Series Micro GCs.One is a laboratory Quad GC and the other is a portable Quad GC. The portable Quad houses a refillable internal carrier gas cylinder and a rechargeable sealed lead-acid battery. The laboratory Quad GC does not offer these features. Overview of Instrument Distinctions H Micro GC Figure 51 Quad-Series instrument front panel Sample inlets: The Quad-Series GC can have one to four sample inlets on the front panel. If you chose the optional rear panel mounted sample inlets, then your sample inlets will be found on the rear panel. 119

126 Quad-Series Micro Gas Chromatograph Quad-Series Micro Gas Chromatographs Analog/control Analog/control AUX 12 VDC in Carrier out Carrier fill 1800 PSI Power 12 VDC H RS-232 Port Carrier in Sample vent Figure 52 Quad-Series instrument rear panel AUX carrier in RS-232 Port Caution Important message below! Please read the following description on the proper connection of the RS-232 communication ports and your computer s serial ports before using your Quad-Series GC. RS-232 Ports: The Quad-Series Micro GC has two RS-232 ports. In order for the Quad-Series GC to function properly, it is imperative that the RS-232 port for Channels A and B be attached to COM 1 on your computer and the RS-232 port for Channels C and D be attached to COM 2 on your computer. Analog/control: The Quad-Series GC has two Analog/Control ports for Channels A and B and Channels C and D. Power 12 VDC: The portable Quad-Series GCs have a rechargeable internal battery pack which requires the use of a battery charger for operation. The laboratory Quad-Series GCs use a 12 VDC power supply for operation. Both the battery charger and the power supply plug into this connector. 120

127 Quad-Series Micro Gas Chromatograph Quad-Series Micro Gas Chromatographs Carrier fill 1800 psi: This option is valid only on the portable Quad-Series GCs. It is used to refill the internal carrier gas cylinder with up to 1800 (1,240 KPa) psi of high purity carrier gas. Carrier out: This option is valid only on the portable Quad-Series GCs. This connector is used AUX 12 VDC in: This option is valid only on the portable Quad-Series GCs. This connector is used for alternate power sources such as the cigarette lighter adapter cables Sample vent: The common outlet vent for the two internal sample vacuum pumps for Channels A, B, C, and D. Carrier in: This connection provides an inlet for a primary carrier gas to Channels A, B, C, and D. AUX carrier in: This connection is to be used only when it is desirable to use two different carrier gases. For example, Helium may be used on Channels A and B, while Argon is used on Channels C and D. It is important to understand that Channels A and B share the same carrier gas (i.e., the carrier gas plumbed to the Carrier in connection) and that Channels C and D also share the carrier gas (i.e., the carrier gas plumbed to the AUX Carrier in connection). When only the Carrier in port is used, Channels A, B, C, and D will all share the same carrier gas. The carrier gas configuration is customer specified. Please refer to the P200/P200H Micro Gas Chromatograph and EZChrom Chromatography Data System User s Manuals for all other information regarding the use of your Quad-Series GC and EZChrom

128 Quad-Series Micro Gas Chromatograph Quad-Series Micro Gas Chromatographs 122

129 Appendix C

130 Precolumn backflush-to-vent and the backflush modules Backflush-to-vent Modules Precolumn backflush-to-vent and the backflush modules A GC module with a precolumn backflush-to-vent configuration has two columns a short precolumn and a longer analytical column. The backflush valve lies between the precolumn and the analytical column. The stationary phase and length of the precolumn is chosen so that, at the operating temperature of the columns, undesirable sample components that interfere with the analyses are retained on the precolumn stationary phase. The sample components for quantification have minimal affinity for the stationary phase of the precolumn, and pass quickly through the precolumn. After the last sample component for quantification exits the precolumn and enters the analytical column, the backflush-to-vent valve located between the precolumn and the analytical column opens. The carrier gas flow through the precolumn is reversed and backflushes the undesirable sample components off the precolumn. The sample components for quantification continue to flow through the analytical column for separation and detection. At the end of the analytical run, the backflush GC module is fully purged of all sample components and is ready for the next analysis. Theory of operation of the precolumn backflush-to-vent Figure 53 is a schematic diagram of an Agilent micro gas chromatograph with a precolumn backflush-to-vent GC module, during sample injection. During sampling, the backflush and sample valves are open and the inject and foreflush valves are closed. Sample gas is drawn into the GC by the pump or the sample gas pressure. The sample gas fills the sample chamber in the injector. A section of the sample chamber is a "fixed-volume" sample loop. The sample valve closes, then the sample gas in the chamber is pressurized and the backflush valve closes. 124

131 Theory of operation of the precolumn backflush-to-vent Next, the inject valve and foreflush valve open. Carrier gas flows from the opened foreflush valve into the sample chamber at one end of the fixed-volume section of the sample chamber. The carrier gas from the foreflush valve forces the sample gas from the fixed-volume section of the sample chamber through the opened inject valve, and into the carrier gas flow to the precolumn and analytical column. The sample gas in the fixed-volume section passes through the inject valve and injects in about 1 second. As the injected sample gas flows through the precolumn, the sample components begin to separate spatially. The foreflush valve and inject valve remain open until the sample components for quantification exit the precolumn and enter the analytical column. At the "Backflush At" time, the foreflush valve closes, the backflush valve opens, and the flow of carrier gas through the precolumn reverses-or backflushes. All sample components remaining on the precolumn backflush to the sample vent, while the sample components for quantification continue to flow through the analytical column to the detector. The amount of sample gas injected depends on the volume of the fixed volume section, and on the temperature and pressure of the sample gas in the fixed- 125

132 Theory of operation of the precolumn backflush-to-vent volume section at the moment sample injection begins (Ideal Gas Law: PV = nrt). Figure 53 Injection event schematic for backflush GC module Carrier gas pressure surges WARNING Carrier gas pressure surges greater than 1.4 psig/sec may damage the analytical columns. It is critical in BFMs to set the column head pressure knobs to deliver zero psig before startup see Figure 54. If full pressure is applied to the BFM, the precolumn phase dislodges from the column wall and flakes away causing a flow restriction. Flow restrictions are known to change the retention times, peak elution, Backflush at Times and even destroy the detector. Therefore, it is necessary to always back-out the column head pressure knobs for BFMs before turning on the carrier gas. To ensure the integrity of the analytical columns in BFMs, do not subject the columns to pressure surges. Before connecting a BFM to carrier gas, set the 126

133 Theory of operation of the precolumn backflush-to-vent column head pressure knob to zero psig by turning the knob counter clockwise. After the carrier gas is connected, slowly turn the knob clockwise to increase the column head pressure to original operating condition. To view column head pressure open the Status window in EZChrom. As standard practice with BFMs, the column head pressure should be set to zero psig when finishing up for the day. To protect the GC, turn the detectors off and cool the columns to about 40 C. Then, turn the column head pressure knob counter clockwise until the carrier gas is set to deliver zero psig. It will take about 10 minutes for the pressure in the columns to decline to below 5 psig. Caution To protect the detectors, always turn the detectors off before decreasing column head pressure to zero psig. The manifold delivers a column head pressure of about zero when, looking down the edge of the BFM GC back panel, the black knob is 3/8 inch from the manifold stem. Figure 54 shows the knob position for zero column head pressure. Channel D Channel C Channel B Channel A Figure 54 Knob position for zero column head pressure 127

134 Eight steps to backflush method development Figure 55 shows the knob position for 30 psig column head pressure. The manifold delivers a column head pressure of around 30 psig when the black knob becomes difficult to adjust. Channel D Channel C Channel B Channel A Figure 55 Knob position for 30 psi column head pressure. Eight steps to backflush method development Use this eight step guide for developing new methods for a GC module with the precolumn backflush-to-vent configuration (i.e., Modules A, B, and C in the standard BFM). Verify that the GC is ready for sample analysis and a sample source is connected to the GC sample inlet before starting method development. Consider using the Starter Method and the operating parameters used for the Sample Run provided with your GC as the starting point for method development. 1. Set the column temperature and column head pressure as appropriate. See Figure 58 for guidance on the appropriate operating parameters for your BFM. 2. Set the "B backflush At" time to a value likely to produce the desired chromatogram. See Figure 58 for guidance on the appropriate operating 128

135 Eight steps to backflush method development parameters for your BFM. In the absence of more specific guidance, set the "Backflush At" time to 10 seconds. As the "Backflush At" time is reduced, fewer sample components exit the precolumn and pass into the analytical column for separation, detection, and quantification. When modifying the "Backflush At" time, begin by changing the time by ± 1 second, eventually using ± 0. 1 second increments to fine tune the "Backflush At" time. The maximum "Backflush At" time is 25.5 seconds; in 0.1 second increments. Figure 56 Instrument setup window for quad 129

136 Eight steps to backflush method development Figure 57 Instrument setup window for M/P Set the sampling time to 15 seconds or longer so that the BFM receives a sample with consistent composition to the GC analytical column. Use shorter sampling time only if you obtain reliable results. Avoid sampling times shorter than 5 seconds. 4. Set the run time to 160 seconds. Select a shorter run time if you are certain that all of the sample components for quantification will be detected within the shorter run time. A long run time facilitates the detection of carry-over peaks and the passage of undesirable sample components from the precolumn to the analytical column. 5. Analyze a sample. Determine if all the sample components for quantification appear in the chromatogram. If all the sample components for quantification are not detected, go to step Change the Method and BFM operating parameters to optimize the analysis. Adjust the column temperature, column head pressure, or "Backflush At" time to optimize the analysis. Potential improvements to the analysis include: detecting all the sample components for quantification; reducing 130

137 Eight steps to backflush method development the run time needed to get peaks for all the sample components for quantification; improving peak separation; and reducing the "Backflush At" time. In general, shorter "Backflush At" times and lower column head pressures yield better chromatography. Increasing the column temperature generally improves peak shape for the late-eluting peaks. On the downside, increasing the column temperature can undesirably reduce the resolution of the early-eluting peaks in the chromatogram. k. If peaks for all the sample components for quantification appear in the chromatogram, monitor the peak area of the last peak for quantification. The "last peak for quantification" means the peak with the longest "retention time" among the peaks used for calculating sample results. If the size or shape of the last peak for quantification causes inaccurate peak integration, then monitor the peak area of another peak near the last peak. Reduce the "Backflush At" time and rerun the sample. Compare the previous run peak area for the monitored peak to the peak area in the rerun of the sample. If the peak areas agree within 2%, then the shorter "Backflush At" time is preferred. On the other hand, if the previous run peak area of the monitored peak quantification is more than 2% greater than the peak area from the rerun then increase the "Backflush At" time and rerun the sample. Make small adjustments (tenths of a second) when you think you are close to the optimum time, and larger adjustments (1 to 5 seconds) when you are far from optimum time. Find the minimum "Backflush At" time that delivers all the sample components for quantification to the analytical column. Determine the value of this minimum "Backflush At" time, then add some time increment (e.g., 5% to 10%) as a buffer against system variability. For example, if 3 seconds is the minimum time, select 3.3 seconds for the "Backflush At" time. Remember that the "Backflush At" time has a resolution of 0.1 second. Verify the repeatability of the GC with the selected "Backflush At" time. Agilent Technologies suggests analyzing the same sample eight successive times. The peak area RSD ("relative standard deviation") of 131

138 Eight steps to backflush method development the last five runs should be below 2% for the last peak if the peak is adequately resolved. The RSD will generally be below 1% for a wellresolved peak above 1000 ppm. If the RSD exceeds 2%, the "Backflush At" time may be too short to reliably deliver all the sample components for quantification to the analytical column. Increase the "Backflush At" time, the column temperature, or the column head pressure and repeat Steps 5 and 6. Look for carryover peaks. If carryover peaks appear, go to Step 6l. Carryover peaks (from previous samples) may not appear until after the third run. l. If carryover peaks appear, the selected "Backflush At" time is insufficient to separate the sample components of interest from the other components in the sample. Decrease the "Backflush At" times a few tenths of a second or reduce the column temperature a few degrees and then repeat Steps 5 and 6. The "time window" between the minimum "Backflush At" time to pass all the sample components for quantification and the "Backflush At" time that allows undesirable sample components to enter the analytical column widens as the column temperature decreases. m. If all the sample components for quantification were successfully detected, consider further adjustments of the method to optimize the analysis. Decrease the run time, or increase the column temperature or column head pressure. Increasing the column temperature or increasing the column head pressure causes faster elution of the sample components. Increasing the column head pressure, tends to reduce the minimum "Backflush At" time required. Changes to the column temperature or the column head pressure may require adjustment of the "Backflush At" time (by repeating Steps 5 and 6). 7. If any sample component for quantification is not detected, increase the column temperature, increase the column head pressure, or increase the "Backflush At" time, then and repeat Steps 5 and 6. Try increasing temperature by 5 C to 20 C, pressure 3 to 8 psig, or "Backflush At" time- 1 to 5 seconds. 132

139 Connecting a sample to the backflush modules 8. If the chromatography achieved following Step 1 through Step 7 is not satisfactory, the particular precolumn and analytical column combination in the module may not suit the analysis attempted. Connecting a sample to the backflush modules All samples delivered to the sample inlet on the front panel of the GC must be gases with the following characteristics: Low pressure: ambient to 30 psig Room temperature No particulate contamination No liquid contamination If the sample meets all the characteristics listed above, proceed and connect the sample directly to the GC sample inlet. Particulate-free samples in Tedlar bags usually meet all the characteristics required for direct connection to the BFM sample inlet. If the sample does not meet all of the above characteristics, you must condition the sample before the sample enters the GC. Analytical columns in the backflush modules Standard column configurations for BFMs are listed in Table

140 Sample component identification Table 25 Analytical Columns in the Standard BFM Carrier Gas Precolumn Analytical Column Ar/He Molsieve 13x, 2.0m x 0.32mm ID Molsieve 5Å, 10m x 0.32 mm ld He RT QPLOT, 1.0 m x 0.32 mm ID PoraPLOT U, 8 m x 0.32 mm ID He RT Alumina, 1.0 m x 0.32 mm ID Al 2 O 3 s Deactivated 10m x 0.32mm ID Sample component identification Table 26 is a list of the recommended channel for identification and quantification of each common gas sample component. Although several sample components may be quantifiable on more than one channel. The channel that usually provides the best separation and quantification for that sample component is listed in Table 26. The BFM gas analysis chromatograms in this section provide further details regarding the identification and quantification of common gas sample components. Table 26 Channel for Optimal Sample Component Identification and Quantification Chemical Class Sample Component Optimal Column for Quantification Permanent Gases Helium Molsieve 5Å Hydrogen Molsieve 5Å Oxygen Molsieve 5Å Nitrogen Molsieve 5Å Carbon Monoxide Molsieve 5Å Carbon Dioxide PoraPLOT U C 1 - C 3 Hydrocarbons Methane Molsieve 5Å or PoraPLOT U Ethane Ethylene Acetylene PoraPLOT U PoraPLOT U PoraPLOT U 134

141 Sample component identification Chemical Class Sample Component Optimal Column for Quantification Propane PoraPLOT U or Al 2 O 3 Propylene PoraPLOT U or Al 2 O 3 1,2 - Propadiene Al 2 O 3 Propyne (methyl acetylene) Al 2 O 3 C 4 Hydrocarbons n - Butane Al 2 O 3 iso - Butane Al 2 O 3 iso - Butene Al 2 O Butene Al 2 O 3 trans Butene Al 2 O 3 cis Butene Al 2 O 3 1, 3 - Butadiene Al 2 O Butyne Al 2 O 3 C 5 Hydrocarbons n - Pentane Al 2 O 3 iso - Pentane Al 2 O 3 neo - Pentane Al 2 O 3 Cyclopentane Al 2 O Pentene Al 2 O 3 trans Pentene Al 2 O 3 cis Pentene Al 2 O Methyl Butene Al 2 O Methyl Butene Al 2 O Methyl Butene Al 2 O 3 C 6+ Hydrocarbons Methylcyclopentane Al 2 O 3 135

142 Sample component identification Chemical Class Sample Component Optimal Column for Quantification 2,2 - Dimethylbutane Al 2 O 3 2, 3 - Dimethylbutane Al 2 O Methylpentane Al 2 O Methylpentane Al 2 O 3 Misc. Compounds Hydrogen Sulfide PoraPLOT U Sulfur Dioxide PoraPLOT U Carbonyl Sulfide PoraPLOT U 136

143 Example chromatograms from backflush modules Example chromatograms from backflush modules Molecular Sieve 5Å Analytical Column: 10 m x 0.32 mm ID, 30 µm film, Molecular Sieve 5Å Column Temperature: 110 C Carrier Gas: Argon; CHP = 30 psi Timed Parameters: Sampling Time = 15 sec, Run Time = 160 sec Injector: Fixed Volume of 1.0 µl Detector: TCD at Low sensitivity Backflush Mode: Precolumn = 2 m Molecular Sieve 13X, Backflush At = 8 sec Peak No. Sample Component 1 Helium 2 Hydrogen 3 Nitrogen 4 Methane 5 Carbon Monoxide 137

144 Example chromatograms from backflush modules PoraPLOT U Analytical column: 8 m x 0.32 mm ID, 10 µm film, PoraPLOT U Column Temperature: 80 C Carrier Gas: Helium; CHP = 32 psi Timed Parameters: Sampling Time = 15 sec, Run Time = 160 sec Injector: Fixed Volume of 1.0 µl Detector: TCD at Low sensitivity Backflush Mode: Precolumn = 1.0 m PoraPLOT Q, Backflush At = 7 sec Peak No. Sample Component 1 Carbon Dioxide 2 Ethylene 3 Ethane 4 Acetylene 5 Hydrogen Sulfide 6 Propane/Propylene 7 1,2-Propadiene 8 Methyl Acetylene (Propyne) 138

145 Example chromatograms from backflush modules Alumina Analytical column: 10 m x 0.32 mm ID, 8 µm film, Al 2 O 3 Column Temperature: 140 C Carrier Gas: Helium; CHP = 25 psi Timed Parameters: Sampling Time = 15 sec, Run Time = 160 sec Injector: Fixed Volume of 0.4 µl Detector: TCD at Low sensitivity Backflush Mode: Precolumn = 1.0 m Al 2 O 3, Backflush At = 5 sec Peak Sample Component Peak Sample Component 1 n-propane 12 3-methyl- 1 -Butene 2 Propylene 13 trans-2-pentene 3 iso-butane 14 2-methyl-2-Butene 4 n-butane 15 1-Pentene/2-methyl-1-Butene 5 trans-2-butene 16 cis-2-pentene 6 1 -Butene 17 Methylcyclopentane/2,2-Dimethylbutane 7 iso-butene 18 2-Butyne 8 cis-2-butene 19 2,3 Dimethylbutane/2-Methylpentane 9 iso-pentane 20 3-Methylpentane 10 n-pentane 21 n-hexane 11 1,3-Butadiene 139

146 Other applications for the BFM Other applications for the BFM The BFM can do gas-related analyses, such as: Stack Gas Analysis (N 2,O 2, CO, CO 2, H 2 S, CH 4, C 2 H 6, C 2 H 4, C 2 H 2 ) Reductive Flue Gas Analysis (H 2, CO 2, N 2 O, SO 2, H 2 S, O 2, N 2, CH 4, CO) Liquefied Petroleum Gas (LPG) using a sample vaporizer Extended Natural Gas Analysis with specification of C 6 +components Analysis of Trace Level Impurities in Ethylene and Propylene Feedstocks Refinery Gas Typical BFM operating parameters Table 27 Typical BFM Analyzer Operating Parameters Column Type Sample Time (sec) Backflush Time (sec) Column Temp. ( C ) Column Flow rate* (ml/min ) Column Head pressure (psig) Molsieve 5Å 15 4 to 9 90 to to 35 PoraPLOT U 15 4 to 9 80 to to 35 Alumina 15 3 to to to 35 *Analytical column carrier gas flow rate as measured with a bubble flow meter at the analytical column vent. Benefits of BFMs The precolumn with backflush-to-vent optimizes the analyses and vents the unwanted sample components before reaching the analytical column as seen in Figure 58. The precolumn is used to retain undesirable sample components 140

147 Benefits of BFMs which attribute to poor separation, sample carry-over, and extended run times. In this way BFMs ensure long-term column performance and eliminates time between analyses due to sample carry-over. Figure 58 Chromatograms with and without backflush Peak No. SampIe Component Peak No. Sample Component 1 iso-butane 4 Nitrogen 2 iso-pentane 5 Methane 3 Oxygen 6 Ethane Plus 141

148 Troubleshooting Troubleshooting Table 28 Troubleshooting Guide Disap- Peaks pear If the "Backflush At" time is too short, the peaks of interest may be backflushed to vent. Try increasing the "Backflush At" time, in 1 second intervals. Check the current method for any changes to the: "Backflush At" time, Column Head Pressure, Inject Time, Column Temperature. Detectors(On/Off) or Run Time. Check the Detector Autozero in the Instrument Status window. If the Autozero is +/- 440 mv, the detector is dead and must be sent to Agilent Technologies for repair. If late eluting peaks are missing and all method parameters are the same, try conditioning the columns. Column temperatures for the Molsieve Å and the Alumina columns should be set to 180 C for reconditioning. The recommended PoraPlot U column reconditioning temperature is 160 C. 142

149 Troubleshooting Unknown Peaks Unknown peaks which occur after the first run may be late eluting peaks carrying over from prior runs. Try decreasing the "Backflush At" time in 0.5 to 1 second intervals. (Carry over peaks are typically rounded and flat). Extra peaks may occur if the carrier pressure to the GC is not set to 80 psig. Injector valves will not function properly, and may cause a double injection. Air components appearing in the chromatogram can be caused by a leak in the GC. To check the GC for a leak: set the inject time to zero, set "Backflush At" time to zero and run an analysis. If the analysis shows any peaks, the GC may need to be repaired at Agilent Technologies. If a sample is not connected properly, air will appear in the chromatogram. Check the sample connections. Retention Time Shifts Column temperature changes will cause retention time shifts. Check the past calibration data for original method parameters. Changes in column head pressure will cause retention time shifts. Check the past calibration data for original method parameters. Check the retention time of the unretained peak, (air composite). If the retention time has shifted out at the same column temperature and pressure, the GC may be damaged and require servicing at Agilent Technologies. Environmental temperature changes will cause retention time shifts when the column temperature is set below or at room temperature. Most common temperature swings are from heated buildings to outdoor winter climates that attribute to retention time shifts. 143

150 Troubleshooting Reduced Peak Areas Dirty sample filters can restrict flow causing reduced peak areas. Change external filters and try another analysis. The sample inlet has a 1 µm frit filter in the fitting. If the filter in the sample inlet is plugged with contaminants, the restriction in flow will cause reduced peak areas. Sample pressure less than zero psig, a vacuum, will show reduced peak areas or even have air peaks appear. Reduced peak areas can be attributed to changes in the method, such as, column temperature, column head pressure, detector sensitivity, inject time and "Backflush At" time". If a module has been recently installed, problems with reduced peaks may be attributed to the module installation. Try re-installing the module. Reseat the module tubing in the manifold by pulling the tubes a millimeter back. 144

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152 Printed on recycled paper This product is recyclable. Agilent Technologies Printed in USA 4/00 Manual Part No. G