TES Construction Standards 17 Instrumentation. Revision #: 2.2 Document #: CS17063 Page: 1 of 26 Title: Instrument Specifications-Flow

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1 Revision #: 2.2 Document #: CS17063 Page: 1 of PURPOSE Provide guidelines for specifying flow instruments. 2. SCOPE Specification of flow instruments at the Kankakee site. 3. RESPONSIBILITY It is the responsibility of all who design (including modifications) instrumentation or control systems at the Kankakee site to follow this procedure. 4. SAFETY MEASURES N/A 5. MATERIAL AND EQUIPMENT 5.1 Consult Kankakee Project Engineering and the Maintenance E&I department for recommended device manufacturers. 5.2 Consult the BASF NA Regional standard device list Instrumentation, and G-S-790 for BASF global standard device list Instrumentation. 6. DEFINITIONS N/A 7. PROCEDURE 7.1 Drawings Site Standards Instrument Installation Detail Drawings 7.2 Protocols If available, specify transmitters with either a 4-20 ma Hart or Foundation Fieldbus output depending on the application. 7.3 Terminology and Equations Velocity Profile The velocity profile of a flowing stream is a critical parameter when selecting and installing flow meters. It is the reason why certain technologies require a straight run of pipe upstream and downstream of the meter. Pipe elbows and valves distort the velocity profile and cause errors in measurement. There are two types of velocity profiles commonly referred to in flowmeter selection. They are laminar and turbulent. Below are drawings showing each profile. These profiles are directly related to a dimensionless coefficient called the Reynolds number. The Reynolds number is a ratio of inertial forces to viscous forces. It is defined by the following equation: vd / = density lb/ft³

2 Revision #: 2.2 Document #: CS17063 Page: 2 of 26 V = velocity in ft/sec D = pipe diameter in inches = viscosity in centipoise Typically, if the Reynolds number is below 2000 the flow is laminar. If the Reynolds number is above 4000 the flow is turbulent. In between 2000 and 4000 there is a transition region where the velocity profile is unpredictable. The Reynolds number usually only becomes an issue in liquid flow. Due to the low viscosity encountered in gas and steam flow they are almost always in the turbulent region. Laminar Flow Velocity Profile Turbulent Flow Velocity Profile In reviewing the drawings above it becomes obvious why turbulent flow is preferred. In laminar flow there is a much higher velocity in the center of the pipe than near the wall. In turbulent flow the velocity is more consistent across the diameter of the pipe. Most flowmeters are sensitive to the velocity profile of the fluid Liquid Flow Liquid flow is typically expressed in either volumetric (gpm) or mass units (lb/hr). Below are some useful equations when applying liquid flow meters. Convert lb/hr to gpm, Gpm = lb/hr / 500 x sg Sg = specific gravity Calculate specific gravity of liquid, Sg = density of liquid (lb/ft³) / density of water (lb/ft³) Calculate velocity of a liquid, V = q / d² V = velocity in ft/sec Q = flow in gpm D = diameter of pipe in inches

3 Revision #: 2.2 Document #: CS17063 Page: 3 of 26 To convert English to metric units, use conversion factors available in many reference manuals. In addition, there are several websites such as that will perform various conversions Gas Flow Gas flow is typically represented in standard units such as SCFM (Standard Cubic Feet Per Minute). This represents the flow at standard conditions which are 14.7 psia and 60 ºf. Sometimes either the data is given in ACFM (actual cubic feet per minute) or the flowmeter requires the sizing to be done using these units. To convert from actual conditions to standard conditions use the following equation: (ACFM) x (Ts/Ta) x (Pa/Ps) = SCFM To convert from standard to actual, (SCFM) x (Ta/Ts) x (Ps/Pa) = ACFM Ts = Temperature at Standard in Degrees Rankin = = 520 Ta = Temperature at Actual Conditions in Degrees Rankin = ºF Ps = Pressure at Standard Conditions in Psia = 14.7 Psia Pa = Pressure at Actual Conditions in Psia = Psig Other useful equations and conversions used for gas flow are as follows: Convert lb/hr to scfh, Scfh = lb/hr x 379 / m M = Molecular Weight Convert Ncm(Normal Cubic Meters)/hr to Scfh Scfh = Ncm/hr x Calculate Velocity of a gas, V = (qh x tf) / (pf x d²) V = Velocity in Ft/Sec Qh = Flow Rate in Scfh Pf = Flowing Pressure in Psia Tf = Flowing Temperature in Degrees Rankin (ºf + 460) D = Diameter of Pipe in Inches Calculate Specific Gravity of Gas, Sg = Molecular Weight of Gas / Molecular Weight of Air Molecular weight of air = 29 Calculate Density of Gas, = M x Pa / Ta Z = Density in lb/ft³

4 Revision #: 2.2 Document #: CS17063 Page: 4 of Data Gathering M = Molecular Weight Pa = Operating Pressure in psia Ta = Operating Temperature in Degrees Rankin (ºf + 460) Z = Compressibility Ratio (Typically near 1 in normal applications) Before writing a specification for any flow device, gather all the data that will define the requirements. These requirements are as follows: Process Data Flow, Pressure, Temperature, Physical Properties, etc Hazardous Area Classification Signal Type Analog, Fieldbus, etc Power Supply 24Vdc or 120Vac Piping Specifications Process Type Sanitary or not 7.5 Features While writing the instrument specification, consider which features that you want to select that are offered by a flow device. Some of these are as follows: Local Indication (Preferred) Remote Mounted Transmitter (Transmitter mounted separate from sensor) Stainless Steel Mounting Brackets Enclosure Rating Materials of Construction Chemical compatibility of parts in contact with process fluid including seals General housing compatibility with area environment GMP Considerations 7.6 Accuracy Requirements The accuracy requirements of an application are sometimes poorly defined and often misunderstood. Several factors must be considered when defining the requirements for an instrument. They are rangeability, linearity, accuracy, and repeatability. The rangeability is defined as the ratio of the maximum to minimum values that the instrument can effectively read while still staying within the limits of its accuracy specification. It is typically represented in terms such as 10 to 1. The linearity is defined as the closeness to which an instrument s input vs. Output represents a straight line. It typically is represented as a percent of reading. Accuracy is the conformity of an indicated value to a recognized accepted standard value, or ideal value. It is typically represented as a percent of reading, percent of span or a deviation of the actual unit of measurement (e.g. +/- 1ºf). Repeatability is the closeness of agreement among several consecutive measurements of the output for the same value of the input under the same operating conditions,

5 Revision #: 2.2 Document #: CS17063 Page: 5 of 26 approaching from the same direction. It typically is represented as a percent of reading or a deviation of the actual unit of measurement. In many cases absolute accuracy is not as important as repeatability. Many operators know that when they set the setpoint of a control loop at a certain value their process operates well. The actual value is not as important in this case. It is more important that the instrument is repeatable so that the operator gets the same results consistently. Examples of cases where accuracy becomes more critical are inventory, ingredient addition, and custody transfer applications. 7.7 Orifice Plates Theory of Operation Orifice plates are based on Bernoulli s theorem which states that in a flowing stream, the sum of the pressure head, velocity head and the elevation head at one point is equal to their sum at another point removed in the direction of flow from the first point plus the loss due to friction between the two points. This principle is applied to flow measurement by altering the velocity of the flow stream in a predetermined manner, usually by a change in the cross-sectional area of the stream. Typically, the velocity at the throat of a flow nozzle inserted in a pipe is increased relative to the velocity in the pipe. There is a corresponding increase in velocity head. Neglecting friction and change of elevation head, there is an equal decrease in pressure head. This difference between the pressure just upstream of the nozzle and at the throat of the nozzle is measured. Velocity is determined from the ratio of the cross-sectional areas of the pipe and the nozzle, and the difference of velocity heads given by the differential pressure measurements. Flow rate derives from velocity and area. The basic equations are: V = k h/ Q = ka h/ W = ka h V = velocity Q = volumetric flow rate W = mass flow rate A = cross-sectional area of pipe h = differential pressure = density k = ratio of cross-sectional area of pipe to cross sectional area of nozzle Two important characteristics of head flow measurement are shown from the equations. One is that density effects both mass and volumetric measurements.

6 Revision #: 2.2 Document #: CS17063 Page: 6 of 26 The other is that the flow is proportional to the square root of the differential pressure. This square root relationship is what limits the rangeability of all head type measurements. Orifice Plate Flow Profile Concentric Orifice Plate Advantages and Disadvantages The advantages and disadvantages of the orifice plate are as follows: ADVANTAGES DISADVANTAGES -Simple Technology -Limited Rangeability -Low Hardware Costs -Non-linear Signal -Used with 2-wire transmitter -Requires Straight Pipe Run -Accuracy Affected by Wear -Increased Installed Cost Due to Tubing -Freeze protection may be required Design The most commonly used orifice plate is the concentric sharp-edged orifice. Quadrant edge orifices are used when the Reynolds number goes below 10,000. Eccentric orifices and segmental orifices can be used for liquids containing solids or gases containing liquids Orifice plates are not recommended for slurries or dirty liquids Orifice plates are not recommended for erosive or corrosive fluids which tend to round the sharp edge of the orifice Specify vent holes for liquid services with small amounts of entrained gas Specify drain holes for steam or vapor services where condensation can occur The beta ratio,, is equal to the orifice diameter divided by the pipe inside diameter. For best accuracy it is recommended to hold this ratio to a range of 0.2 to A typical differential pressure used for sizing orifice plates is 100 inches of water. Other values can be used but this is typical Keep impulse lines as short as possible to minimize errors.

7 Revision #: 2.2 Document #: CS17063 Page: 7 of When using tubing, the transmitter can be used on processes with temperatures greater than its rated limits. This is because there is no flow in the tubing and the heat is dissipated from the tubing. 1/ wall tubing will typically dissipate a minimum of approximately 200 F per foot. This number will vary based on the tube size and thickness and the difference in process and ambient temperature. Caution should be used when two valve and three valve manifolds are used in these services. If operated incorrectly the manifold can create flow through the tubing which brings the hot process media right to the transmitter In some applications, especially outside, it may become necessary to install the transmitter in an insulated case with a heater and either steam or electrically trace the impulse lines. Standard insulated tube bundles are available for these types of installations On gas and vapor service if a mass flow signal is required install multivariable transmitters that measure pressure and can also accept a temperature signal for pressure and temperature compensation of the flow signal. Locate the temperature sensor at least 10 pipe diameters downstream of the orifice plate Flange taps are typically used for lines 2 and above. For smaller lines corner taps are usually used In line sizes less than 2 it is recommended to purchase an entire meter run from the factory. The piping in these meter runs is honed out to provide a smooth finish Install the orifice plate with the required amount of straight run per the ASME requirements. The amount of straight run varies depending on the upstream piping configuration. A typical meter run would be 20 pipe diameters upstream and 5 pipe diameters downstream A Flow straightener can be installed to reduce the amount of straight run required for the installation Orient the orifice plate in the piping per the manufacturer s recommendations. See the list below for the typical preferred installations. Liquids Horizontal or Vertical Up Gases Horizontal or Vertical Down Steam Horizontal or Vertical Down When installing liquid containing impulse lines for an orifice plate in a vertical line, the lower impulse line must be brought up to the upper line to eliminate any error due to a difference in elevation of the taps Orifice plates are much less popular than in the past because of the newer technologies now available. Vortex meters are now used in many installations that were previously done with orifice plates Orifice plates are still commonly used as restrictions in pipe lines. When sizing a restriction orifice in a liquid flow line use the same equation as a metering orifice except use full flow taps as the sizing basis. There are special equations for critical flow orifices in gas applications.

8 Revision #: 2.2 Document #: CS17063 Page: 8 of Install 3-valve manifolds at the transmitter to be able to zero the transmitter Integral orifice transmitters should be used for very small flows. 7.8 Averaging Pitot Tube Theory of Operation The averaging pitot tube flow element produces a differential pressure signal proportional to the square of the flow rate. The high pressure is produced by impact of the flowing fluid on the upstream side of the sensor. The velocity profile of the fluid results in a corresponding impact pressure profile. Multiple sensing ports on the upstream face of the sensor sense the impact pressure profile. Inside the high pressure chamber the average impact pressure is maintained by the proportionality of the sensing port diameters to the chamber cross-sectional area. As the fluid flows around the sensor, it generates vortices that create a low-pressure profile. The low pressure is used as a pressure reference, so the velocity can be determined independent of the static pressure in the pipe. The low pressure is sensed by ports located on the downstream face of the sensor. Using the same principle as the high-pressure side an average low-pressure signal is produced Advantages and Disadvantages The advantages and disadvantages of the averaging pitot tube are as follows: ADVANTAGES DISADVANTAGES -Simple Technology -Limited Rangeability -Low Hardware Costs -Non-linear Signal -Good for Installing in Large -Requires Straight Pipe Run Pipes -Small Ports Can Plug -Some Designs Can Be -Increased Installed Cost Due to Removed Under Pressure Tubing -Low Pressure Drop -Freeze protection may be required -Used With 2-wire Transmitter

9 Revision #: 2.2 Document #: CS17063 Page: 9 of Design Follow vendor recommendations for straight run requirements when installing an averaging pitot tube In lines that cannot routinely be shutdown, install averaging pitot tubes with insertion assemblies that allow installation and removal of the element under pressure Integral mounted transmitters eliminate impulse line errors Install differential pressure transmitters following the same guidelines as orifice plates Averaging pitot tubes are good for measuring flow in large lines or ducts Select a pipe size that develops a high enough velocity to produce a differential pressure higher than the vendor recommended minimum to guarantee good performance. In some cases, this will require downsizing the section of pipe where the pitot tube is located Longer averaging pitot tubes require additional support at the opposite of the pipe. Consult with the vendor for guidelines Vibration is created by forces developed as vortices are shed by the averaging pitot tube. The range of the velocities that can cause this problem can be calculated. Changes in the mounting and probe diameter should be made to avoid this problem Averaging pitot tubes can be used to monitor air flow in large ducts. These applications typically involve very low differential pressures; therefore, specials models should be used for these services. Brandt is a manufacturer that offers units designed for this type of service. 7.9 Flow Nozzles Theory of Operation The flow nozzle consists of a convergent inlet section and a downstream cylindrical throat. As in an orifice plate the differential pressure produced is proportional to the square of the flow rate.

10 Revision #: 2.2 Document #: CS17063 Page: 10 of Advantages and Disadvantages The advantages and disadvantages of the flow nozzle are as follows: ADVANTAGES DISADVANTAGES -Simple Technology -Limited Rangeability -Less Pressure Drop (Loss) than -Non-linear Signal Orifice Plate -Requires Straight Pipe Run -Better for Higher Velocities than -More Difficult to Replace than Orifice Plate Orifice Plate -Higher Capacity than Orifice -Increased Installed Cost Due to Plate Tubing -Dimensionally more Stable than -Freeze protection may be required Orifice Plate -Not recommended for low Reynolds -Used With 2-wire Transmitter Number Services (<50,000) Design Follow vendor recommendations for straight run requirements when installing a flow nozzle meter Follow the same installation guidelines as an orifice plate Flow nozzles are not recommended for slurries or dirty fluids Install differential pressure transmitters following the same guidelines as orifice plates Venturi Theory of Operation The venturi tube consists of a straight inlet section of the same diameter as the inlet pipe where the high pressure tap is located; a converging section in which the velocity increases with an increase of velocity head and a decrease in pressure head; a cylindrical throat where the low pressure tap is located and the velocity is neither increasing or decreasing; and a diverging recovery cone where the velocity decreases and the pressure is recovered. As in an orifice plate the differential pressure produced is proportional to the square of the flow rate.

11 Revision #: 2.2 Document #: CS17063 Page: 11 of Advantages and Disadvantages The advantages and disadvantages of the venturi are as follows: ADVANTAGES DISADVANTAGES -Simple Technology -Limited Rangeability -Less Pressure Drop Than -Non-linear Signal Orifice Plate -Requires Straight Pipe Run -Used With 2-wire Transmitter -Costly in Larger Sizes -Increased Installed Cost Due to Tubing -Freeze protection may be required 7.11 Vortex Design Follow vendor recommendations for straight run requirements when installing a venturi meter Install differential pressure transmitters following the same guidelines as orifice plates Theory of Operation When a fluid flow meets an un-streamlined obstacle, such as the bluff body in a vortex meter, boundary layers are formed on the surface of the body. These boundary layers separate and move downstream, forming a vortex. These vortices peel off, or shed, first from one side of the body and then the other, forming a vortex train behind the body. The frequency of this shedding is directly proportional to the velocity of the flow. Vortex meters sense the pressure generated by the vortices Advantages and Disadvantages The advantages and disadvantages of the vortex meter are as follows: ADVANTAGES DISADVANTAGES -10:1 Rangeability -Requires Straight Run -Simple Design -Flow Must be Turbulent -No Moving Parts -No flow signal below low flow cutoff -Easy to Install -Digital Signal Available -2-wire Transmitter

12 Revision #: 2.2 Document #: CS17063 Page: 12 of Design The vortex meter is the preferred meter for steam flow measurement The vortex meter is a good choice for low viscosity liquid, gas or steam Problems can be encountered with fluids that will coat the bluff body Accuracy will be reduced in multi-phase flow applications. Wet, low quality steam is an example of this service. The liquid phase must be homogeneously dispersed within the steam. Installations in vertical lines should be avoided in these cases. In addition, turn the meter body so that the bluff body is horizontal which leaves the bottom of the pipe open to help prevent build-up Low pressure gases can be a problem due to their low density. Low density gases do not produce a strong enough pulse, especially if velocities are low The Reynolds number should be above 10,000 for optimum performance For services with low vapor pressure liquids ensure that flashing and cavitation do not occur due to the meter pressure drop Excessive pipe vibration can be a problem. Supporting the pipe up and down stream of the meter or rotating the sensor so that it is not in the plane of vibration can help Vortex meters are not recommended for batching services especially if dribble control is used. This is due to the low flow cutoff that is inherent with these meters. The low flow cutoff is the point where the vortex meter output is zero for any flow lower than this value The vortex meter has the same requirements for straight run as an orifice plate Use the vendor s sizing program to select the proper size meter. The meter should be selected so that the minimum flow is above the low flow cutoff and the maximum flow produces a reasonable pressure drop ( 4 psi) Specify remote electronics if the line is subject to vibration or if the meter is in an inaccessible location Typically, both analog and digital signals are available from the vortex meter. The digital signal is more accurate because it does not have the inaccuracy attributed to the A/D conversion Insertion styles for larger lines are available from some vendors Coriolis Theory of Operation The Coriolis meter consists of a straight or U-shaped tube that is vibrated at its natural frequency. As the fluid passes through the tube it causes the tube to deflect in proportion with the mass flow rate. Sensors in the meter body measure the amount of deflection. In addition, the meter can also be used to measure density.

13 Revision #: 2.2 Document #: CS17063 Page: 13 of 26 Changes in density will change the frequency at which the tube vibrates. This frequency is measured, and the density is calculated by the transmitter Advantages and Disadvantages The advantages and disadvantages of the Coriolis meter are as follows: ADVANTAGES DISADVANTAGES -Reliable and Accurate -High Cost -Straight Run Not Required -High Pressure Drops -Not Affected by Changes in -Some Styles Not Easily Physical Properties Drained -Density and Temperature -External Power Typically Required Signals Available Design Use the vendor s sizing program to select the proper size meter Since this type of meter can produce larger pressure drops than other technologies, coordinate with the process engineer Use the straight through style meter for sanitary applications when selfdraining is a requirement Entrained air can cause inaccuracies. The installation of air eliminators is recommended for these types of services Downsizing the meter is acceptable. However, it is not recommended on corrosive, viscous, or abrasive services Consult the factory when installing two meters close to each other to discuss the possibility of crosstalk between them Ensure that the piping designers are providing the proper pipe supports as required by the vendor It is recommended that block valves and calibration valves be installed up and down stream of the meter for applications where calibration can be done in line The meter must be zeroed with the sensor full. On horizontal pipe installations install a valve downstream of the meter to stop flow. On

14 Revision #: 2.2 Document #: CS17063 Page: 14 of Magmeters vertical installations install a valve upstream of the meter to keep the sensor full In some designs the wiring between the sensor and the transmitter is intrinsically safe. In hazardous areas do not route this wiring in the same raceway with non-intrinsically safe wiring Orient sensor body per vendor s recommendations. Meters on liquid flows must be installed in a location in the piping so that they are always full Theory of Operation Magmeters operate on the principle of Faraday s Law which states, motion at right angles between a conductor and a magnetic field generate a voltage in the conductor proportional to the relative velocity between the conductor and the magnetic field. In a magmeter the fluid is the conductor and the magnetic field is produced by applying an alternating electrical signal to the magnetic coils wrapped around the tube of the meter. There is a pair of electrodes in the magmeter that sense the voltage Advantages and Disadvantages The advantages and disadvantages of the magmeter are as follows: ADVANTAGES DISADVANTAGES -Independent of Viscosity, Density -Relatively Expensive Turbulence and Consistency -Requires Minimum Conductivity -Measures Difficult Fluids -Affected by Entrained Gas -No Obstruction to Flow -Affected by Electrode Coating -Pressure Drop Same as Pipe -External Power Required -Handles Bi-directional Flow Design These meters are especially useful on corrosive, highly viscous and abrasive streams.

15 Revision #: 2.2 Document #: CS17063 Page: 15 of Turbine Orient meter body to keep full Most magmeters require a minimum conductivity of 5 microsiemens. Varying conductivities do not affect meter accuracy if they stay above the minimum value. Special lower conductivity meters are available but should be used with caution In electrically non-conductive pipes specify grounding rings to be installed immediately upstream and downstream of the meter In horizontal lines orient the sensing electrodes horizontally. This is due to the potential of air pockets at the top of the pipe or sediment in the bottom Use the vendor provided or recommended sensor cables Specify remote electronics when the line is subject to vibration or the meter is installed in an inaccessible location Insertion style meters are available and should be considered for larger lines Some vendors recommend that the magmeter be installed with a minimum of 5 pipe diameters upstream and 2 pipe diameters downstream. This maintains accuracy and minimizes liner wear Pulsed DC magmeters provide higher efficiency, lower power consumption, higher accuracy, more stable zero, and less bulk than AC magmeters. AC meters should be considered on applications involving slurries with non-uniform particle size, large quantities of entrained gas, or pulsating flow at a frequency less than 15 Hertz Meters are available in a variety of lining and electrode materials Size the magmeter to maintain adequate velocity per the vendor s recommendations. Higher velocities will tend to clean the electrodes. Velocities for abrasive slurries should be kept below 10 ft/sec to reduce wear on the liner Grounding is critical in a magmeter installation due to the low voltages produced. Follow vendor s recommendations for grounding Theory of Operation The fluid enters a turbine meter through the front rotor support. This item provides support for the rotor and conditions the fluid to be measured. The fluid passes the rotor forcing it to spin at an angular velocity that is proportional to the fluid s linear velocity and volumetric flow rate. The pick-off assembly converts the rotor s velocity to a frequency signal.

16 Revision #: 2.2 Document #: CS17063 Page: 16 of Advantages and Disadvantages The advantages and disadvantages of the turbine meter are as follows: ADVANTAGES DISADVANTAGES -High Rangeability and Accuracy -Moving Parts -Digital Signal -Upstream Filter Recommended -Small Size for Given Capacity in Some Applications -Ease of Maintenance -Straight Run Required -Fast Response -Calibration Difficult -Bearing Wear Affects Accuracy -Over-speeding Can Cause Damage -Generally, for Clean Services Design Turbine meters are usually selected due to their high accuracy, repeatability, linearity and rangeability Turbine meters are good for process accounting and batching services Size turbine meters so that the average expected flow is between 60 to 75% of the maximum meter capacity Follow vendor recommendations for orientation and straight run requirements when installing a turbine meter Make sure on applications involving low vapor pressure liquids, that flashing, or cavitation do not occur due to the meter pressure drop In liquid services install the meter so that no air flows through it which can overspeed and damage the bearings Make sure the flow is limited to the range of the meter since flows above the upper limit can cause damage to the bearings Protect the meter from water hammer in liquid applications by using throttling valves or slow closing on-off valves.

17 Revision #: 2.2 Document #: CS17063 Page: 17 of Special bearings are required for non-lubricating applications such as gases and water Use pre-amplifiers to boost the signal and provide more noise immunity Filters or strainer may be required in some applications Positive Displacement Theory of Operation The fluid entering the positive displacement meter is divided into segments momentarily which are then displaced at the outlet. These segments are precise volumes which are multiplied by the total number of displacements to obtain the total volume. The pick-off assembly generates a frequency signal proportional to volumetric flow rate. Oval Gear Meter Advantages and Disadvantages The advantages and disadvantages of the positive displacement meter are as follows: ADVANTAGES DISADVANTAGES -High Accuracy -Moving Parts -No Straight Run Required -High Pressure Drop on Viscous -Simple and Easy to Maintain Liquids -Digital Signal -Upstream Filter Recommended -Good for Pulsating Flow -Subject to Wear -Slippage Around Rotors Design The main cause of error in a positive displacement meter is slippage around the rotors. The slip increases as viscosity drops. Therefore, these meters perform best on higher viscosity services These meters have relatively high pressure drops when applied to viscous liquids. This should be discussed with the process engineer Positive displacement meters are used extensively in the petroleum industry.

18 Revision #: 2.2 Document #: CS17063 Page: 18 of Thermal Mass Positive displacement meters are recommended for clean, lubricating fluids and start-stop short duration runs Air eliminators may be required to keep the meter full and to protect against over-speeding the bearings The meters should be protected against excessive flows by installing a control valve or other means of limiting flow beyond the meter specifications Strainers or filters should be installed upstream of the meter if solids are present in the line Protect the meter from water hammer in liquid applications by using throttling valves or slow closing on-off valves These meters should never have steam pass through them The pressure on gas meters should be applied and released slowly Positive displacement meters are sensitive to viscosity changes below approximately 100 centipoise Vendors usually recommend a minimum back pressure of 5 psig on the meter to ensure that the meter is full Theory of Operation This flowmeter uses two RTDs to measure mass flow rate. One of the RTDs is heated by an electric current that raises the RTD temperature above the temperature of the surrounding media. The other RTD is not heated and it measures the temperature of the process media and is referred to as the reference RTD. When the fluid flows past the RTDs, a quantity of heat is removed from the heated RTD and is carried off into the flow stream. The amount of heat removed is a function of the mass flow rate. A temperature differential exists between the two RTDs and a corresponding resistance differential. The resistance differential is measure by the transmitter and the mass flow is calculated and converted to an output signal.

19 Revision #: 2.2 Document #: CS17063 Page: 19 of Advantages and Disadvantages The advantages and disadvantages of the thermal mass meter are as follows: ADVANTAGES DISADVANTAGES -High Rangeability -Relatively High Cost -Insertion Style for Larger Lines -Requires Straight Run -Ability to Install and Remove -Requires External Power Insertion Style under Pressure -Factory Calibration Design Follow vendor s recommendations for orientation and straight run requirements These meters are good for main gas header flows due to high rangeability and the ability to remove the insertion style under pressure Give process data to vendor to check sizing Provide installation information to contractor for installing insertion style meters. These meters have a certain orientation related to the direction of flow and they are sensitive to the insertion length into the pipe Insertion style meters can be installed through a full port ball valve to be able to install and remove them under pressure. The insertion assembly varies depending on the line pressure Avoid applications where dirt or condensation can build-up on the sensor Use remote mounted transmitters when the meter is exposed to vibration or is mounted in an inaccessible location Use the vendor supplied or recommended cable between the sensor and the transmitter Thermal elements are commonly used for flow switches. However, they are relatively expensive when used in this service compared to other switches.

20 Revision #: 2.2 Document #: CS17063 Page: 20 of Ultrasonic - Doppler Theory of Operation Doppler ultrasonic flowmeter operates on the principle of the Doppler effect. A transmitted frequency is altered linearly by being reflected from particles and bubbles in the fluid. The frequency shift between transmitted and received frequencies is directly proportional to flow rate. The Doppler meter consists of a transmitter and receiver which are clamped to the outside of the pipe and the electronics which detect the difference between the transmitted and received frequencies Advantages and Disadvantages The advantages and disadvantages of the ultrasonic Doppler meter are as follows: ADVANTAGES DISADVANTAGES -Non-intrusive -Fluid Must Have Minimum -Easy to Install on Existing Pipes -Amount of Bubbles or Solids -Straight Run Required Design Refer to the vendor s requirements related to the minimum amount of bubbles or solids needed in the flow stream for proper operation Typically, these meters have a minimum Reynolds number threshold of The locations of the transducers are critical and should strictly follow the vendor s guidelines. Provide an installation detail to the contractor that not only supplies the locations but also gives directions for the proper mounting of the transducers The pipe must always be full Follow vendor s recommendations for mounting and straight run requirements The ratio of pipe diameter to pipe wall thickness should be greater than 10 to 1.

21 Revision #: 2.2 Document #: CS17063 Page: 21 of Transducers must be mounted so that there is no air space between them and the pipe wall These meters are not recommended for use on lined pipe. In some cases, wetted transducers can be used to overcome the signal attenuation in these services Ultrasonic Transit Time Theory of Operation Transit Time flowmeters measure the difference in travel time between ultrasonic pulses transmitted in a single path in the direction of and against the flow. The difference in travel times in the upstream and downstream directions is proportional to the flow rate. The Transit Time meter consists of two transducers mounted outside the pipe which act as transmitters and receivers for ultrasonic beams and the electronics which detects the difference in travel time and produces a signal equal to the volumetric flowrate Advantages and Disadvantages The advantages and disadvantages of the ultrasonic transit time meter are as follows: ADVANTAGES DISADVANTAGES -Non-intrusive -Fluid must be Clean Fluid -Easy to Install on Existing Pipes -Straight Run Required -External Power Required Design These meters are recommended for clean fluids that are a reasonable conductor of sonic energy. Discuss service with vendor Typically, these meters have a minimum Reynolds number threshold of The locations of the transducers are critical and should strictly follow the vendor s guidelines. Provide an installation detail to the contractor that

22 Revision #: 2.2 Document #: CS17063 Page: 22 of Rotameter not only supplies the locations but also gives directions for the proper mounting of the transducers The pipe must be full at all times These meters are affected by the speed of sound through the liquid. If this changes during measurement, errors will occur Ambient acoustic noise can affect these meters Follow vendor s recommendations for mounting and straight run requirements The ratio of pipe diameter to pipe wall thickness should be greater than 10 to Transducers need to be mounted so that there is no air space between them and the pipe wall These meters are not recommended for use on lined pipe. In some cases, wetted transducers can be used to overcome the signal attenuation in these services These meters are used commonly on cryogenic liquids and molten metals Theory of Operation The rotameter is a variable area flowmeter. It consists of a tapered tube and a float that is free to move up and down. The fluid enters the bottom and flows up and around the float. As the fluid enters the bottom of the tube, the float is lightened by the buoyant force, but this is not enough to raise the float. There is a small annular opening between the float and the tube. The pressure drop across the float increases and raises the float increasing the annular area until the upward forces on it are balanced by its weight. The float moves up and down in proportion to the annular area and the flow rate. As the annular area increases, the pressure drop across the float decreases. Each position of the float corresponds to a certain flow rate at a given density and viscosity.

23 Revision #: 2.2 Document #: CS17063 Page: 23 of Advantages and Disadvantages The advantages and disadvantages of the rotameter are as follows: ADVANTAGES DISADVANTAGES -Low Cost for Local Indication -Moving Parts -Good for Purge Applications -Effected by Changes in Density -Straight Run Not Required -Low Pressure Drop -Must Be Installed Vertically -Metal Tube Type Expensive -Glass Tubes are Fragile Design These meters are recommended for local indication of clear fluids with process conditions that allow the use of glass tubes. Metal tubes are available, but they are costly The most popular use of rotameters is for purging applications. Specify a constant flow regulator integrally mounted to the rotameter for these services Other accessories are available such as switches and transmitters but are not used very often because other technologies are more popular and less expensive Meters installed in gas service require a minimum backpressure to function properly. If the density of the gas drops too low the float will not raise Glass tubes cannot be used on dirty or opaque fluids Glass tubes should not be used for alkaline solutions which will attack glass. An example of this would be caustic Protect glass tubes from water hammer and thermal shock Specify a shield with glass tube meters to protect personnel in the event of a tube rupture Avoid using glass tubes on abrasive slurries which can wear away the glass Meter accuracy is affected by varying viscosities A wide variety of types and metering options are available Paddle/Vane Flow Switch Theory of Operation Paddle and Vane type flow switches operate by the flowing media pressing against the paddle or vane. The paddle or vane is attached to a mechanism that is attached to a switch of some type. Vendors use different means of transmitting the force on the vane or paddle to the switch mechanism, but the concept is the same.

24 Revision #: 2.2 Document #: CS17063 Page: 24 of Advantages and Disadvantages The advantages and disadvantages of the paddle flow switch are as follows: ADVANTAGES DISADVANTAGES -Simple Design -Moving Parts -Easy to Install -Questionable Reliability -Low Cost Design These switches should only be installed on clean services These type switches have a history of being unreliable. They are not recommended in critical services If the mechanism gets fouled in any way the switches will stop working or not actuate at the proper setpoint Summary Changes in technology have made a big impact on how flowmeters are selected. In the 1970s head type meters such as orifice plates were by far the most used technology. With the development of vortex meters and Coriolis mass meters this has changed. Vortex meters are the meter of choice for steam applications. They are also good choices to be installed in what were typical orifice plate installations. This is due to their increased rangeability, accuracy and simplicity of installation. While the hardware costs are higher the overall installed cost is lower, and the reliability is higher. The improvements in Coriolis mass meter technology have increased their use greatly in the last 15 years. They provide direct mass flow measurement and very good accuracy and reliability. In many cases they are the preferred meter. The main drawbacks are high cost and higher pressure drops. The necessity of using such a high cost meter needs to be reviewed with every application. Magnetic flowmeters still are a good choice for hard to handle applications, such as, corrosive and abrasive materials. Thermal mass meters are good choices for gas flows when high rangeability is required. Due to their relatively high cost other technologies should also be considered when the rangeability requirements are not as high. Retractable insertion style meters should be evaluated for main header flows into plants. The retractable feature allows them to be installed and removed under pressure. Meters in this service should have good rangeability due to the wide changes in flows typically encountered in these applications. Insertion style meters should also be considered for larger line sizes due to the cost of in-line meters in larger sizes.

25 Revision #: 2.2 Document #: CS17063 Page: 25 of 26 Ultrasonic meters should be considered for large line sizes, installation on an existing line, hard to handle liquids, or a temporary installation. These meters are available in portable models that are typically used to check flows in existing lines. Turbine meters and positive displacement meters continue to be used in many batching and custody transfer applications of clean fluids. 8. APPENDICES/FORMS Specification sheets for all flow devices are found in CS17063SS Flow Specification Sheets accessed in Documentum under Forms/. CS17063A Flow Meter Annubar CS17063B Flow Meter Magnetic CS17063C Flow Meter Mass CS17063D Orifice Plate CS17063E Flow Meter Rotameter CS17063F Flow Meter Vortex CS17063G Flow Meter Site Glass 9. REFERENCES/SOP S 9.1 Codes and Standards NEC and NFPA standards ISA Standards ANSI / API RP 551 Process Measurement Instrumentation Site Standard Drawings (See Section 7.1.1) Site Engineering and Construction Specifications CS17001 Instrumentation Mechanical Installation CS17002 Instrumentation and Controls Electrical Installation

26 Revision #: 2.2 Document #: CS17063 Page: 26 of REVISION HISTORY Rev # Page Description of Change Change Coordinato r Date 0 All Original J. Shute 08/16/ All Updated BASF Header on procedure and specification sheets. Reviewed, no changes made to content. Remove Revision on all specification sheets Format update, remove references to obsolete Kankakee standard, minor change. We updated the revision number to next level as we changed CS17063A TO CS17063SS. J. Shute 02/15/2013 J. Shute 04/05/2016 J. Shute 2/8/2019