LI-670. Flow Control Unit. Instruction Manual

Transcription

1 LI-670 Flow Control Unit Instruction Manual

2 LI-670 Flow Control Unit Operating and Service Manual

3 NOTICE The information contained in this document is subject to change without notice. LI-COR MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. LI-COR shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. This document contains proprietary information which is protected by copyright. All rights are reserved. No part of this document may be photocopied, reproduced, or translated to another language without prior written consent of LI-COR, Inc. Copyright 1992, LI-COR, Inc. Printing History New editions of this manual will incorporate all material since the previous editions. Update packages may be used between editions which contain replacement and additional pages to be merged into the manual by the user. The manual printing date indicates its current edition. The printing date changes when a new edition is printed. (Minor corrections and updates which are incorporated at reprint do not cause the date to change). 1st Printing - June, 1992 Publication Number June, 1992 LI-COR, Inc Superior Street Lincoln, Nebraska FAX: Toll-free (U.S. & Canada) ii

4 Table of Contents Section 1. Unpacking What's What Optional Accessories Section 2. Pre-Operation Power On Battery Operation AC Power Filling the Scrubber Tubes Section 3. Operation Description Front View Rear View Internal View Applications Calibrating LI-COR Infrared Gas Analyzers Absolute and Differential Mode Calibration with One Span Gas Measuring in Absolute Mode Measuring in Differential Mode Reminders and Precautions iii

5 Section 4. Maintenance Replacing the Air Pump Diaphragm Internal Air Filters Recharging the 6200B Battery Soda Lime/Desiccant Tube 'O'-ring Seals Fuses Appendix A. Appendix B. Specifications List of Suppliers Warranty iv

6 Section 1 Unpacking What's What Check the packing list included with your LI-670 to verify that you have received everything that was ordered, and that you have also received the following items: Battery Leads For connection to a user-supplied battery ( VDC) or other DC power supply. Jumper Cable For connection to the LI-COR LI-6251, LI-6252, or LI-6262 infrared gas analyzers. Using this jumper, the LI-670 can be used to supply power to the analyzer; the LI-670 can be also be powered from the analyzer when the analyzer is operated with AC or battery power. Soda Lime/Desiccant Tube Assemblies Two each of the soda lime and desiccant tube assemblies are included. See Section 2, Pre-Operation for instructions on filling these tubes. Spare Parts Kit The spare parts kit contains replacement parts for your LI-670. As you become familiar with the Flow Control Unit you will learn which items to keep close at hand, and which items can be stored away. Unpacking 1-1

7 Section 1 Optional Accessories Several optional accessories are available for use with the LI-670, including: AC Module ( / VAC, Hz). The AC Module is required only when the LI-670 is used without a LI-COR gas analyzer, as it can be powered from the analyzer. 6200B Rechargeable Battery ( VDC). The 6200B Rechargeable Battery is tested and fully charged before it leaves the factory, but may discharge during shipping. It is a good idea to test your battery to make sure that it is charged. If the battery is below 12 volts, it should be charged before use. Refer to Section 4 for charging instructions. The 6200B requires the LI-6020 Battery Charger for recharging, or it can be recharged directly from a LI-COR gas analyzer. Never store batteries in a discharged state. Charge stored batteries every three months. LI-6020 Battery Charger (92-138/ VAC, 47 to 63 Hz). The LI-6020 can charge up to four 6000B or 6200B Rechargeable Batteries simultaneously. 1-2 Unpacking

8 Section 2 Pre-Operation Power On Battery Operation The 6200B Rechargeable Battery fits into the compartment on the back of the LI-670. To install the 6200B, loosen the two thumbnuts, and lift the bottom of the retaining strap to access the compartment. Place the 6200B in the compartment, and replace the retaining strap. See Table 2-1 for the approximate battery life of the 6000B and 6200B batteries when used with the LI-670. The LOW BATT light will illuminate when the battery reaches approximately 11.5 volts, and will get progressively brighter until it is fully lit at 11 volts. The LOW BATT circuit is enabled when the reference pump switch is set to either the BATT or ON positions. The detection circuit operates when the switch is in the BATT position, and draws approximately 20 ma. Instructions for recharging the 6000B and 6200B batteries are given in Section 4. Table 2-1. Hours of Battery Life for 6000B and 6200B Batteries (@ 25 C ambient). 6000B 6200B Using one pump 12.5 Hours 25 Hours Using two pumps 6.25 Hours 12.5 Hours AC Power If you are installing the , remove the retaining strap. Install the AC Module and replace the retaining strap. Tighten the thumbnuts securely. Connect the output power cable to one of the jacks labeled VDC on the rear panel. Pre-Operation 2-1

9 Section 2 Make sure the AC VOLTAGE selector on the AC module is set correctly (choose the 115 setting for VAC, or the 220 setting for VAC), and plug the line cord into the AC receptacle. WARNING: To prevent personal injury, never operate the AC Module unless it is inserted into the LI-670. Filling the Scrubber Tubes 1. Locate the two CO 2 SCRUB tubes (the longer tubes) and the two H 2 O SCRUB tubes. Remove the caps from one end of the CO 2 SCRUB tubes (the longer tubes). Inspect the caps to make sure that the filter paper covering the mesh over the exit passage within the cap is in place. Fill the CO 2 SCRUB tubes with soda lime. Fill the tubes with soda lime to within cm of the top, and then fill the remaining space with the polyester batting provided. This will help prevent dust formation due to the particles moving within the tubes. Replace the cap on each tube. Remove the red dust caps, and insert the 4 metal unions provided with the LI-670 into the 4 ports designated as the REFERENCE and SAMPLE CO 2 SCRUB loop. The two CO 2 SCRUB tubes may now be connected to the LI-670 by mating the ports in the tube cap with the unions. If you are using the LI-6262 CO 2 /H 2 O Analyzer's water channel, the H 2 O SCRUB tubes need to be filled, also. Remove the caps from one end of the H 2 O SCRUB tubes (the shorter tubes). Inspect the caps to make sure that the filter paper covering the mesh over the exit passage within the cap is in place. Fill the tubes with fresh magnesium perchlorate [anhydrous Mg(ClO 4 ) 2 ] to approximately cm from the top, and replace the caps. Leave a small air space at the top of the desiccant column to prevent caking of the desiccant. Connect the tubes to the REFERENCE and SAMPLE H 2 O SCRUB ports by following the same procedure as for the CO 2 SCRUB tubes. Remove the desiccant tube(s) and shake periodically to break up channels that will form as the magnesium perchlorate absorbs water. 2-2 Pre-Operation

10 Section 2 If you are not using the H 2 O SCRUB tubes, a short piece of the Bev-A- Line tubing can be inserted in place of the scrubber tubes. A list of chemical suppliers is provided in Appendix B. CAUTION: Magnesium perchlorate is a strong oxidizing agent. Contact with skin or mucus membranes may cause irritation. If exposed to skin, wipe off excess and wash with soap and water for 15 minutes. Avoid bringing it into contact with acids and organic substances such as cotton, rubber, grain dust, etc. Consult the container label. 2. Before connecting tubing from other instruments to the LI-670, test the flow rate through the LI-670. With all of the other switches OFF (down position) and the VENT valves closed, turn ON both the reference and sample pumps. With the rotameter valves fully open, there should be over 2 LPM flow through both of the rotameters. The flow will decrease slightly if the CO 2 /H 2 O SCRUB switches are turned ON. Check for the following conditions if one or both of the rotameters indicates zero flow: Pump(s) OFF. AUX switch ON or auxiliary flow path incomplete. DIFF ZERO switch ON and REFERENCE PUMP switch OFF. Vents open. CO 2 /H 2 O SCRUB switch ON and either soda lime or desiccant tube missing, and no jumper in place. Rotameter flow valves closed. Fitting disconnected inside the LI-670. Filter clogged. Torn pump diaphragm. Pre-Operation 2-3

11 Section 3 Operation Description The LI-670 is used to provide and control the flow of air (or other gas) to an infrared gas analyzer. It is designed for modular attachment to LI-COR infrared gas analyzers (LI-6251, LI-6252, and LI-6262) by means of removable mounting brackets which may be affixed to the top of the LI-670 and to the bottom of the gas analyzer, or vice versa. These brackets are included in the LI-670 spare parts kit. The LI-670 can also be used to provide power and a low battery detection circuit for LI-COR gas analyzers. The LI-670 features two independent flow paths - each with a separate pump, scrubbing chemicals, and rotameter - to give complete control over flow into the reference and sample cells of a gas analyzer. Front View Figure 3-1. LI-670 front panel. Operation 3-1

12 Section 3 Pump voltage potentiometers. Two small potentiometer screws adjacent to the reference and sample pump switches permit independent adjustment of the pump speed. The potentiometers control SAMPLE and REFERENCE pump voltages over a range of about 5 to 10 volts, corresponding to nominal flow rates of about 1 LPM to 2.5 LPM. Turn the potentiometer adjustment screws counter-clockwise to decrease the pump speed. Pump ON/OFF switches. The SAMPLE PUMP switch has only ON and OFF positions, but the REFERENCE PUMP switch has three positions; ON, OFF, and BATT. A low battery circuit is active when the REFERENCE PUMP switch is set to BATT or ON, or if the SAMPLE PUMP switch is ON. The LOW BATT light will begin to illuminate when battery voltage reaches about 11.6 volts, and will reach maximum brightness at about 11 volts. This provides a low battery warning for LI-COR gas analyzers when the LI-670 is used as the power supply. The LI-670 draws about 20 ma when the reference pump switch is set to BATT, so be sure it is in the OFF position when the instrument is not in use. SAMPLE and REFERENCE vents. Opening these vents reduces SAMPLE or REFERENCE output flow rates by bleeding off excess flow. The vents are used in conjunction with the rotameter flow valves to provide flow rate control. AUX PORTS switch and vent. This switch diverts the SAMPLE air flow to the AUX OUT port on the LI-670 back panel, where it can be routed to an external device such as a leaf chamber. The air flow returns to the LI-670 through the AUX IN port on the back panel. A vent on the auxiliary input allows some of the external flow to be exhausted, so that the flow rate through the SAMPLE side can be maintained at a low flow rate, while the flow rate to the external device is high. Leave the AUX PORTS switch OFF to bypass these ports and allow the SAMPLE flow to continue normally. DIFF ZERO switch. This switch vents the SAMPLE path air flow to the inside of the LI-670 case, and divides the incoming REFERENCE air flow between the SAMPLE and REFERENCE paths downstream from the switch. This allows the SAMPLE air flow to an external device to be maintained while checking the zero and/or span of a gas analyzer. CO 2 /H 2 O SCRUB switches. These switches divert the SAMPLE or REFERENCE air flow first through a soda lime CO 2 scrubber tube, and then through a magnesium perchlorate H 2 O scrubber tube. Other CO 2 scrubber or H 2 O desiccant chemicals may be used for special purposes. The scrubbers are bypassed when the switches are OFF. Either the CO 2 or H 2 O 3-2 Operation

13 Section 3 scrubber tubes may be replaced by a short piece of Bev-A-Line tubing if a scrubber is not required. SWAP switch. When ON, this switch will interchange the reference and sample flow streams. In the OFF position, the SWAP switch allows flow to continue normally through the reference and sample paths. This switch can be useful when performing operations such as checking for zero offsets when using a gas analyzer in differential mode. Rotameters with valves. Rotameters are provided to measure the SAMPLE and REFERENCE output flow rates. Maximum flow rates of about 2.5 LPM can be achieved in both the SAMPLE and REFERENCE paths when the SAMPLE and REFERENCE vents are closed and the rotameter flow valves are fully open. Flow rates can be reduced to zero smoothly by opening the vents and then closing the rotameter flow valves. It is not a good practice to reduce flow by closing a rotameter flow valve without first opening a vent, as this will pressurize the flow path between the pump and rotameter, which can cause water condensation if the air is moist. Rear View Figure 3-2. LI-670 back panel. Operation 3-3

14 Section 3 Air is drawn in to the LI-670 by the pumps through the REFERENCE IN and SAMPLE IN ports (Figure 3-2). If air is supplied from a regulated pressurized tank, either the REFERENCE IN or SAMPLE IN ports may be used, or the pumps may be bypassed by flowing air into the REF and SAMPLE VENTS and sealing off the REFERENCE IN and SAMPLE IN ports. The AUX PORTS OUT and IN (Figure 3-2) are used when the AUX PORTS switch is ON (see the front panel), and typically function to route the sample flow OUT to some type of chamber and back IN to the LI-670. Air exits the LI-670 through the REFERENCE OUT and SAMPLE OUT ports. The REFERENCE and SAMPLE CO 2 and H 2 O SCRUB tubes are designed with bayonet-mount caps and quick-fit unions for easy removal, and eliminate the need for hose fittings. For different flow configurations, however, 1/4" OD Bev-a-line tubing can be inserted directly into the scrubber tube caps or the instrument back panel by removing the metal unions. If the user desires to scrub either CO 2 or H 2 O, a short section of Bev-A-Line tubing may be used as a jumper across either the CO 2 SCRUB or the H 2 O SCRUB ports. The VDC battery jacks provide the LI-670 with power from either a battery or the AC Module, and allow the user to power other instruments from the LI-670. The external 1A fuse protects the LI-670 pumps. There is an external 1A slow-blow fuse protecting the AC Module. 3-4 Operation

15 Section 3 Internal View Figure 3-3. LI-670 internal view. A 10A internal fuse protects the batteries. The LI-COR 6200B Rechargeable Battery has a built-in 10A fuse, but this fuse is provided in the event that other batteries are used which do not have fuse protection. Two LI-COR air pumps are located on a 1/4" (0.64 cm) thick aluminum plate to reduce noise due to pump vibration. It is sometimes necessary to change the pump diaphragms. A description of how to remove the pump assembly and pump diaphragms can be found in Section 4. Two Gelman 1µm pore size and 20 cm 2 surface area air filters are located ahead of the air pumps (Figure 3-3) to remove any impurities from the airstream. It is not advisable to operate the LI-670 pumps for prolonged periods of time without the filters in place. See Section 4 for instructions on replacing the air filters. Another filter should be in place between the LI-670 and the analyzer optical paths to prevent any desiccant or soda lime dust from reaching the analyzer. These filters will be inside the LI-6251 and LI-6252 CO 2 Analyzers, and outside the LI-6262 CO 2 /H 2 O Analyzer. Operation 3-5

16 Section 3 Applications 1 Calibrating LI-COR Infrared Gas Analyzers Absolute and Differential Mode Calibration with One Span Gas. Absolute mode. Set zero. 1. Connect the analyzer sample cell to the LI-670 Out fitting, and the analyzer reference cell to the LI-670 Reference Out fitting. 2. Enter the station barometric pressure into the LI-COR analyzer. 3. Connect a span tank containing air (not nitrogen) with a known CO 2 mole fraction to the In and Reference In fittings, and turn both the reference and sample CO 2 /H 2 O Scrub switches ON. Use tank pressure to provide flow at a nominal rate near that used during measurements. Final flow rate adjustments can be made with the LI-670 SAMPLE and REFERENCE vents. 4. When the CO 2 reading is steady, adjust the zero potentiometer on the gas analyzer until the display reads zero. Ref. In Aux. Ports Diff. Zero CO2/H2O Scrub Swap Reference In LI-670 CO 2/H2O Scrub Scrub both cells. Absolute mode. Set span. 5. Turn OFF the sample CO 2 /H 2 O Scrub switch. Leave the REFERENCE CO 2 /H 2 O Scrub switch ON. Adjust the flow as needed. 6. Set the analyzer span when the displayed CO 2 reading is steady. Ref. In Aux. Ports Diff. Zero CO 2/H 2O Scrub Swap Reference In LI-670 CO2/H 2O Scrub Scrub only the reference cell. 3-6 Operation

17 Section 3 The analyzer is now ready for use in absolute mode. Differential mode operation requires three additional steps. Differential mode. Set zero. 7. Perform steps 1 through 6, and then turn OFF the REFERENCE CO 2 /H 2 O Scrub switch. Adjust the flow to near that which will be used during measurements. 8. Adjust the CO 2 analyzer to read zero when the displayed CO 2 mole fraction is steady. Only a small adjustment should be necessary (about 5 ppm) when switching from zero to 350 ppm in the reference cell. 9. Enter the span gas CO 2 mole fraction as CREF in the LI-COR analyzer. Read differential CO 2 on the analyzer display. Check the span by scrubbing the sample cell and reading the negative span gas value on the analyzer display. Ref. In Aux. Ports Diff. Zero CO2/H 2O Scrub Swap Reference In LI-670 CO 2/H 2O Scrub Scrub the sample cell. The analyzer zero or span can be checked during measurements by turning ON the Diff Zero switch, and then using whichever scrubbers are needed. Ref. In Aux. Ports Diff. Zero CO 2/H 2O Scrub Swap Reference In LI-670 CO 2/H 2O Scrub Flow the span gas through both cells of the analyzer. Many other calibration variations are possible. For example, you may want to recirculate air in a closed reference loop for absolute mode operation. The plumbing arrangement for this will be described in the next section. Modify these protocols as needed. Operation 3-7

18 Section 3 ➁ Measuring in Absolute Mode Assume that the absolute CO 2 mole fraction of an airstream is to be measured. The most efficient configuration with respect to the longevity of the scrubbing chemicals is to recirculate the reference gas at a low flow rate in a closed loop. The tubing connections for a LI-COR analyzer and the LI-670, as well as the LI-670 front panel settings are illustrated in Figure 3-4. The chopper housing is shown connected in series with the analyzer reference cell in Figure 3-4, but it could also be maintained as a separate circuit with its own scrubber tube as shown in Figure 3-5. Calibrate the analyzer for absolute mode operation as described earlier. Connect the LI-670 to the gas analyzer as shown in Figure 3-4 using the Bev-A-Line tubing included. Switch ON the LI-670 reference side pump. Turn the reference Pump Adjust screw counter-clockwise to decrease the pump speed to its lowest setting (approximately 1 LPM). Make sure that the reference side VENT valve is closed. Switch ON the LI-670 sample side pump. If desired, the sample side flow rate can be decreased by adjusting the pump speed potentiometer or by opening the VENT valve. Connect the air line to be measured to the In port, and switch ON the sample side pump. Adjust the flow rate if necessary and begin making measurements. This scheme can be modified as needed. For example, if only CO 2 measurements are to be made, the H 2 O scrubber tubes can be replaced with short pieces of Bev-A-Line tubing, and the chopper housing scrubber tube (if present) on the analyzer can be filled with only soda lime. Alternatively, you may wish to measure the CO 2 mole fraction of a dry airstream. In this case, retain both soda lime and magnesium perchlorate in the CO 2 /H 2 O scrubber circuits, and place a desiccant or a cold-trap between the AUX OUT and AUX IN ports. Moist air would then be measured when 3-8 Operation

19 Section 3 the AUX switch is OFF, dry air would be measured when the AUX switch is ON, and the ability to scrub either airstream would be retained. Another configuration might use a tank of compressed CO 2 -free air to provide a reference gas at a low flow rate (Figure 3-6). The reference air might be introduced through the LI-670 Reference In port, or through the Reference Vent port, thereby bypassing the pump. If you bypass the pump, the Reference In port should be sealed. In Aux. Ports Diff. Zero CO2/H 2O Scrub Swap Ref. LI-COR Gas Analyzer Reference IN To Chopper Reference In LI-670 CO 2/H 2O Scrub OUT From Chopper IN OUT IN OUT IN OUT Ref Reference Aux. Ports Vents Reference CO 2 Scrub CO 2 Scrub H 2O Scrub Reference H 2O Scrub LI-670 Back Figure 3-4. Hose connections for absolute mode operation when recirculating the reference side air flow. In Aux. Ports Diff. Zero CO2/H 2O Scrub Swap Ref. LI-COR Gas Analyzer Reference IN Mg(ClO 4 ) 2 To Chopper Reference In LI-670 CO 2/H 2O Scrub OUT Soda Lime From Chopper IN OUT IN OUT IN OUT Ref Reference Aux. Ports Vents Reference CO 2 Scrub CO 2 Scrub H 2O Scrub Reference H 2O Scrub LI-670 Back Figure 3-5. Hose connections for absolute mode operation when recirculating the reference side air flow with a separate scrubber tube circuit for the chopper housing. If an auxiliary chamber is attached to the AUX PORTS input, the auxiliary ports switch is turned ON so that the flow through the chamber enters the sample air stream. In some cases the flow rate through the chamber will be much higher than the desired flow through the analyzer. The excess flow can be exhausted by opening the auxiliary port vent on the front panel. Operation 3-9

20 Section 3 When the LI-670 and gas analyzer are supplied with air from a pressurized tank, the analyzer hose connections to its chopper housing are configured for differential mode operation (see the analyzer instruction manual). If the user wants to bypass either of the LI-670 pumps when supplying air from a pressurized tank, the air may be routed into the LI-670 REF VENT port or SAMPLE VENT port. In this case, the REFERENCE IN or SAMPLE IN port should be sealed. ➂ Measuring in Differential Mode Assume that the difference in the CO 2 mole fraction between two airstreams is to be measured. In the first example, consider the setup of an open, flow-through gas exchange system used for measuring leaf CO 2 uptake (Figure 3-6). Calibrate the analyzer for differential mode operation as described earlier, with a flow rate of approximately 0.5 LPM. Ambient air is drawn through a container of 2 liters or more to buffer CO 2 and/or H 2 O fluctuations, by switching the reference and sample pumps ON. The air is divided between the reference and sample sides of the LI-670, and the reference flow rate is maintained at approximately 0.5 LPM. The leaf chamber is connected between the AUX IN and AUX OUT ports. An electronic flow meter is placed ahead of the chamber to measure the incoming flow rate, to avoid errors that may arise from chamber leaks. Air flow is sent to the leaf chamber when the AUX PORTS switch is ON. Return air flow greater than 0.5 LPM is exhausted out the AUX PORTS vent so that the sample and reference flow rates are equal. The analyzer absolute zero and span and differential zero can be checked without interrupting the flow of air through the chamber by turning the DIFF ZERO switch ON and using the appropriate scrubbers. Alternatively, the differential zero can be checked during the measurement by turning the SWAP switch ON [for small differentials (around 10 ppm)]. The positive and negative CO 2 differentials should agree to within about 0.1 ppm, if there are no zero offsets. If there is an offset, the true differential may be found by subtracting the value displayed after the swap was performed from the value shown before the swap, and dividing the difference by 2. This is illustrated by 3-10 Operation

21 Section 3 C s - C r = [(C s - C r + δ) - (C r - C s + δ)]/2, where C r and C s are the reference and sample CO 2 concentrations, respectively, and δ is the offset. In the second example, a compressed tank of air is used for the reference gas, as shown in Figure 3-7. The reference side pump is OFF, and the sample side pump is ON. LI-COR Gas Analyzer Ref. Reference To Chopper In Aux. Ports Diff. Zero CO2/H 2O Scrub Swap IN OUT Mg(ClO 4 ) 2 Soda Lime Reference In LI-670 CO 2/H 2O Scrub Buffer Volume From Chopper Aux. Ports IN OUT IN OUT IN OUT Ref Reference Vents Reference CO 2 Scrub CO 2 Scrub Reference H 2O Scrub H 2O Scrub LI-670 Back Flow Meter Leaf Chamber Figure 3-6. Hose connections for differential mode operation, using a common air source (shown with an auxiliary chamber attached). In Aux. Ports Diff. Zero CO2/H 2O Scrub Swap Ref. LI-COR Gas Analyzer Reference IN Mg(ClO 4 ) 2 To Chopper Reference In LI-670 CO 2/H 2O Scrub OUT Soda Lime From Chopper Ref. Gas IN OUT IN OUT IN OUT Ref Reference Aux. Ports Vents Reference CO 2 Scrub CO 2 Scrub Reference H 2O Scrub H 2O Scrub LI-670 Back Figure 3-7. Hose connections for differential mode operation using a reference gas from an external tank. Operation 3-11

22 Section 3 Reminders and Precautions 1. In general, avoid differential pressurization of the analyzer's reference and sample cells. If the analyzer is calibrated at some differential pressure between the sample and reference sides and then operated under the same conditions, it is possible to make measurements under these conditions. However, for most situations it is advisable to simply vent off most of the flow before it enters the analyzer and then operate with equal and low flow rates through the reference and sample sides. 2. Check the integrity of the LI-670 soda lime and magnesium perchlorate frequently, especially when the CO 2 /H 2 O Scrub switches are on for long periods of time, or when a span tank gas is being scrubbed for absolute calibrations. 3. Do not restrict the flow through the LI-670 with the rotameter valves if the vent upstream is not at least partially open. 4. Pressures exceeding 15 p.s.i. may damage the LI-670 pump diaphragms, or cause the external scrubber tubes to pop off the fittings. 5. If the LI-670 pump is operated at the lowest voltage setting with a static pressure head downstream, it may not restart after it has been turned OFF. In that case, turn the pump speed adjustment screw clockwise to increase the voltage, or release the static pressure from the head. 6. Do not try to power the LI-610 Portable Dew Point Generator, a LI-COR analyzer, and the LI-670 from a single 6200B Rechargeable Battery. Only one analyzer and the LI-670 should be powered from a single battery. 7. It is possible to connect up to 3 batteries to the LI-670 and operate the LI-670 pumps for longer periods than would be possible with a single battery. When using multiple batteries, however, make sure that they are all at the same charge state (voltage) in order to prevent one battery from discharging the others. The normal current load of each LI-670 pump is approximately 200 ma Operation

23 Section 4 Maintenance Replacing the Air Pump Diaphragm The LI-COR pump diaphragms may fail from pressure surges or from prolonged operation; they have a normal operating life of more than 1400 hours. If the pump motor appears to be functioning normally, but the rate of air flow is greatly reduced, it may be an indication that the diaphragm has failed, or that a filter is clogged. A pump diaphragm leak can also cause erratic CO 2 and/or H 2 O readings because a leaking pump can pick up outside air. Test for a pump diaphragm leak by directing your breath into the LI-670 case, and watch for an increase in CO 2 concentration. Two replacement diaphragms are included in the spare parts kit. Spare diaphragms can be ordered from LI-COR under part # Follow these instructions to replace failed diaphragms: 1. Remove the 12 screws (8 on the top and 4 on the bottom) that attach the outer case of the LI-670 to the main body, and slide the cover off. 2. Remove the 6 screws on the bottom of the instrument case which hold the pump bracket/baseplate. Do not loosen the screws on the baseplate that are painted red. These screws attach each pump to vibration grommets, and are coated to prevent loosening due to vibration of the pumps. 3. Disconnect the pump inlet and outlet hoses at the quick-connect fittings. Disconnect the electrical harnesses and remove the pumps. 4. Remove the 4 screws on the pump head to access the diaphragm. Do not remove the 2 screws that are painted red; these screws hold the valvehead assembly together. Maintenance 4-1

24 Section 4 Diaphragm Retainer Connecting Rod Diaphragm Valve Cover Air Out Air In Base Plate Pump Head Figure 4-1a. Pump diaphragm replacement. 5. Remove the diaphragm retaining screw and washer, and lift off the diaphragm. 6. Clean the 2 surfaces of the pump head which are in contact with the diaphragm. Wash the diaphragm with warm, soapy water to remove any talc, if necessary. Apply a thin layer of the grease provided (Dow Corning 111) to the upper pump head surface (Figure 4-1b). Diaphragm Washer Pump Head Air Out Air In Apply a thin layer of Dow 111 grease to the pump head surface. Figure 4-1b. Pump diaphragm replacement. 7. Reattach the new diaphragm to the connecting rod. Align the holes in the diaphragm with the holes on the top surface of the diaphragm retainer, and hold in place while tightening the retaining screw. Make sure that the screw is flush with the surface of the washer. Tighten until the screw is snug (30 inch-ounces). The diaphragm will be curled slightly. Do not overtighten, as the diaphragm could be damaged. 8. Mount the pump head and valve assembly over the diaphragm and replace the 4 screws. Tighten evenly, until the diaphragm begins to bulge slightly around the edge of the pump head assembly (36 inchounces). Overtightening may damage the diaphragm; insufficient 4-2 Maintenance

25 Section 4 tightening may result in leaks, or loosening of the retaining screws due to vibration. 9. Re-install the pump base plate into the instrument case, and tighten the mounting screws firmly. 10. Connect the electrical harness and the inlet and outlet hoses (connect the air inlet hose to the barb on the pump head labeled IN). Internal Air Filters The frequency with which the Gelman air filters need to be replaced will depend upon the operating environment. Change the filters if you notice the flow rate dropping. The two filters are located inside the LI-670 case, on the hoses leading from the SAMPLE IN and REFERENCE IN fittings, as shown in Figure 4-3. Before installing a new filter, blow clean dry air through it to remove any fibers or other debris that may be loose inside. Old filters can be removed by pressing the red ring toward the center of the connector and pulling off the short piece of Bev-A-Line tubing. Attach a 1 1/4" (3.18 cm) piece of 1/4" (0.64 cm) O.D. Bev-A-Line tubing to the new filter(s) and insert the tubing into the coupling. Air In 1µm PTFE I N µpart I N # Air Out Figure 4-2. Install with lettering toward inlet ports. Install the new filter(s) with the blue lettering facing toward the SAMPLE IN or REFERENCE IN ports (Figure 4-2). Spare filters can be ordered from LI-COR under part # (1 each). Maintenance 4-3

26 Section 4 Figure 4-3. Location of internal air filters. Recharging the 6200B Battery Make sure that the voltage selector slide switch on the back of the LI-6020 Battery Charger is set to appropriate line voltage (115 or 230 VAC). Plug the charger into mains power. The AC indicator light will illuminate. The CHARGE indicator will illuminate if any of the batteries connected to the charger are being charged. One method for testing a battery s charge is to connect it by itself into the charger. If it is charged, the CHARGE light will come on for only a few seconds. If the CHARGE light illuminates with no batteries connected, the AC voltage selector switch on the back is in the wrong position. A fully discharged 6200B battery will require about 4 hours to recharge. Four discharged batteries connected simultaneously would require 16 hours to recharge. The 6200B can also be charged by a LI-COR gas analyzer, even when the analyzer is powered OFF. 4-4 Maintenance

27 Section 4 NOTE: The AC Module is not a battery charger. Charge the 6200B batteries with the LI-6020 Battery Charger or with a LI-COR gas analyzer. Soda Lime/Desiccant Tube 'O'-ring Seals The soda lime and desiccant tubes contain O-ring seals in the caps. Extra O-ring seals are included with the soda lime/desiccant tube assemblies, and can be ordered under part # A modified screwdriver is also included in the spare parts kit to facilitate removal of the O-rings should they need to be replaced. The screwdriver can be inserted behind the O-ring to aid in prying it out. A small container of grease is provided in the spare parts kit; spread a thin layer over the O-rings as needed should they become dry. Fuses If the LI-670 pumps fail to operate when turned ON, check the 1A external fuse on the back panel of the LI-670 AC Module. Alternatively, the 1A external fuse protecting the pumps (located near the VDC jacks) may also be checked. Finally, check either the 10A internal fuse in the LI-670 (Fig. 3-3), or the 10A internal fuse in the 6200B Battery. Maintenance 4-5

28 Appendix A. Specifications Pump Life: Motor: Diaphragm: Pump Voltage Adjustment: >3500 hours typical. >1400 hours typical Volts. Maximum Flow Rate: 2.5 liters min -1. Power Requirement: Flow Meters: Flow Meter Accuracy: Filter Life: Max. Input Pressure: Low Battery Detection: VDC, 0.5 amps. (2) Dwyer series RMA. 2.5 liters min -1 full scale. ± 4% of full scale reading. 1 year typical (dependent upon operating environment). 15 p.s.i. (103.4 kpa). 11 Volts. Connectors: Rapid connect hose fittings for 1/8" (0.32 cm) ID by 1/4" (0.64 cm) OD plastic tubing. Weight: 4.42 kg (9 lbs. 12 ozs.); 6.58 kg (14 lbs. 8 ozs.) with 6200B Rechargeable Battery or AC Module. Size: cm (W H D). 12" 6.25" 8". Specifications A-1

29 Appendix B. List of Suppliers The company names, addresses, and phone numbers are the most current we have at the time of this printing. In some cases the information may change without notice. Soda Lime Part #S-201-3, Mesh 6-12 Fisher Scientific 711 Forbes Avenue Pittsburgh, PA (412) (LI-COR Part # ) Magnesium Perchlorate - Anhydrous Part #M Fisher Scientific (Address above) Part #C260M61 (P74935) Thomas Scientific Vine Street at Third Box 779 Philadelphia, PA (215) Manufactured by G. Frederick Smith Chemical Co. P.O Box Columbus, OH (614) Cat. # VWR Scientific P.O. Box 7900 San Francisco, CA (415) B-1 Suppliers

30 Warranty Each LI-COR, inc. instrument is warranted by LI-COR, inc. to be free from defects in material and workmanship; however, LI-COR, inc.'s sole obligation under this warranty shall be to repair or replace any part of the instrument which LI-COR, inc.'s examination discloses to have been defective in material or workmanship without charge and only under the following conditions, which are: 1. The defects are called to the attention of LI-COR, inc. in Lincoln, Nebraska, in writing within one year after the shipping date of the instrument. 2. The instrument has not been maintained, repaired, or altered by anyone who was not approved by LI-COR, inc. 3. The instrument was used in the normal, proper, and ordinary manner and has not been abused, altered, misused, neglected, involved in and accident or damaged by act of God or other casualty. 4. The purchaser, whether it is a DISTRIBUTOR or direct customer of LI-COR or a DISTRIBUTOR'S customer, packs and ships or delivers the instrument to LI-COR, inc. at LI-COR inc.'s factory in Lincoln, Nebraska, U.S.A. within 30 days after LI-COR, inc. has received written notice of the defect. Unless other arrangements have been made in writing, transportation to LI-COR, inc. (by air unless otherwise authorized by LI-COR, inc.) is at customer expense. 5. No-charge repair parts may be sent at LI-COR, inc.'s sole discretion to the purchaser for installation by purchaser. 6. LI-COR, inc.'s liability is limited to repair or replace any part of the instrument without charge if LI-COR, inc.'s examination disclosed that part to have been defective in material or workmanship. There are no warranties, express or implied, including but not limited to any implied warranty of merchantability of fitness for a particular purpose on underwater cables or on expendables such as batteries, lamps, thermocouples, and calibrations. Other than the obligation of LI-COR, inc. expressly set forth herein, LI-COR, inc. disclaims all warranties of merchantability or fitness for a

31 particular purpose. The foregoing constitutes LI-COR, inc.'s sole obligation and liability with respect to damages resulting from the use or performance of the instrument and in no event shall LI-COR, inc. or its representatives be liable for damages beyond the price paid for the instrument, or for direct, incidental or consequential damages. The laws of some locations may not allow the exclusion or limitation on implied warranties or on incidental or consequential damages, so the limitations herein may not apply directly. This warranty gives you specific legal rights, and you may already have other rights which vary from state to state. All warranties that apply, whether included by this contract or by law, are limited to the time period of this warranty which is a twelve-month period commencing from the date the instrument is shipped to a user who is a customer or eighteen months from the date of shipment to LI-COR, inc.'s authorized distributor, whichever is earlier. This warranty supersedes all warranties for products purchased prior to June 1, 1984, unless this warranty is later superseded. DISTRIBUTOR or the DISTRIBUTOR'S customers may ship the instruments directly to LI-COR if they are unable to repair the instrument themselves even though the DISTRIBUTOR has been approved for making such repairs and has agreed with the customer to make such repairs as covered by this limited warranty. Further information concerning this warranty may be obtained by writing or telephoning Warranty manager at LI-COR, inc. IMPORTANT: Please return the User Registration Card enclosed with your shipment so that we have an accurate record of your address. Thank you.

32 4421 Superior Street P.O. Box 4425 Lincoln, NE U.S.A. Phone: FAX: Toll-free (U.S. & Canada)