TN260/TN360 Series Mass Flow Controllers and Meters

Transcription

1 TN260/TN360 Series Mass Flow Controllers and Meters User Guide Celerity, Inc. 915 Enterprise Boulevard Allen, TX USA T F REV /08

2 _CONTENTS _1.0 GENERAL DESCRIPTION 1 _2.0 PRINCIPLE OF OPERATION 2 _2.1 FLOW SENSOR 2 _2.2 BYPASS (FLOW-SPLITTER) 3 _2.3 VALVE (MASS FLOW CONTROLLERS ONLY) 4 _2.4 ELECTRONICS 4 _2.5 COVER 5 _3.0 INSTALLATION 6 _3.1 GAS CONNECTIONS 6 _3.2 ELECTRICAL CONNECTIONS 6 _3.3 ENVIRONMENTAL REQUIREMENTS 7 _3.4 CALIBRATION 7 _3.5 MOUNTING 8 _4.0 OPERATING INSTRUCTIONS 9 _4.1 INSTALLATION AND START-UP 9 _4.2 SAFETY FEATURES AND PRECAUTIONS 9 _4.3 OPERATING MODES 10 _4.4 ROUTINE AND PREVENTATIVE MAINTENANCE 11 _5.0 MAINTENANCE, ADJUSTMENT AND RANGE CHANGE 12 _5.1 CLEANING 12 _5.2 BYPASS ASSEMBLY 16 _5.3 SENSOR REPLACEMENT 17 _5.4 VALVE ADJUSTMENT (TN260 AND TN261) 17 _5.5 VALVE ADJUSTMENT (TN262 ONLY) 19 _6.0 TROUBLESHOOTING PROCEDURES 21 _6.1 INITIAL TEST 21 _APPENDIX A - GAS FLOW CONVERSION FACTORS 36 _APPENDIX B - PROCEDURES TO AVOID CONTAMINATION 48 p.i

3 _INTRODUCTION GENERAL DESCRIPTION The Celerity TN260/TN360 series Mass Flow Controllers and Meters accurately and reliably measure and control the mass flow rate of gases up to 300 standard liters per minute (200 slm for controllers) without the need for pressure or temperature corrections. Flow Controllers incorporate a valve and appropriate electronics to automatically regulate flow in response to an external command. They have been specifically designed to allow operation on any gas having a known molar specific heat ( ρcp). The entire flow path, including the valve and sensor, is constructed of 316 Stainless Steel, which allows usage with reactive and high purity gases. The TN260/TN360 series is calibrated for specific gases and are manufactured for many standard flow ranges. In some instances, by applying appropriate conversion factors, they can be operated on gases other than the one for which they were originally calibrated. With the use of Celerity's calibrators, the flow range and designated gas can be quickly changed by adjusting the electronics and replacing the valves and/or bypass assembly. The instrument operates on ±15 VDC power, provides a 0 to 5.0 VDC indicated output signal linearly proportional to the flow rate. It is both mechanically and electrically interchangeable with most Celerity mass flow controllers, and is equipped with a 20-pin card edge connector. It can have 0 to 5 VDC or 4 to 20 ma input/output signals. The TN260/TN360 series of mass flow instruments include: Mass Flow Controllers TN sccm to 5 slm TN slm to 20 slm TN slm to 200 slm Mass Flow Meters TN sccm to 5 slm TN slm to 20 slm TN slm to 300 slm p.1

4 _DESCRIPTION PRINCIPLE OF OPERATION The flow controller is a self-contained, closed-loop control system which measures the mass rate of gaseous flow through the instrument, compares this with an externally commanded flow rate, and adjusts the valve to control the flow to the commanded level. The flow controller consists of four basic elements which accomplish this function: The flow sensor The bypass, or flow-splitter, which determines the full-scale flow range of the measuring section The control valve The electronics which condition the flow signal and drive the control valve 2.1 FLOW SENSOR The flow sensor consists of two self-heated resistance thermometers wound around the outside diameter of a thin walled capillary tube. These coils, each having a resistance of 330 ±13 ohms at 24 C, are connected in a bridge circuit and supplied with a regulated current. The heat generated by the power dissipated in the coils raises the tube temperature approximately 70 C above ambient. At no flow, this heat is symmetrically distributed along the tube. With gas flowing in the sensor tube, heat is carried downstream. The resulting shift in temperature makes the upstream sensor cooler than the downstream sensor. This temperature difference (and its corresponding electrical resistance difference) is directly proportional to the mass flow rate of the gas through the tube. The bridge output, being a direct function of the resistance difference, is amplified and further linearized by the electronics to give a 0 to 5.0 VDC indication of flow rate. Increasing the flow rate well above the full-scale range of the instrument will eventually cool the entire sensor tube and the output signal will reverse and asymptotically approach zero. p.2

5 _DESCRIPTION 2.0 Figure 1: Flow Sensor The capillary tube is dimensioned to have minimal mass (for fast response) and an extremely large length-to-diameter ratio to ensure laminar flow over the full operating range.the housing which encases the sensor tube is precisely configured to minimize both external and internal natural convection currents from one coil to the other, thus allowing the instrument to be mounted in any position with no zero adjustment required to re-establish the original calibration. This patentpending configuration minimizes the mass of the sensor resulting in a time constant that is one-third that of other sensors of similar design. Overall flow controller response can therefore be dynamically controlled to eliminate overshoot. 2.2 BYPASS (FLOW-SPLITTER) The bypass, which is located in the primary flow path in the base assembly, produces a linear pressure drop versus flow rate between the inlet and outlet of the sensor tube, which in turn produces a 0 to 100% sensor flow for 0 to 100% flow of the instrument. In order to ensure a constant ratio between sensor flow and total flow (independent of pressure, temperature and gas properties), the bypass has been designed to maintain the flow well within the laminar region of fluid flow over the entire range of the instrument. Since the bypass assembly is the major range - determining factor, it is designed to be easily removed for range changes. p.3

6 _DESCRIPTION 2.0 Figure 2: Bypass (Exploded View) 2.3 VALVE (MASS FLOW CONTROLLERS ONLY) Each flow controller has a unique, patented, normally open control valve. This solid state valve has no moving seals, no friction, and no mechanical wear. Operating on the principle of thermal expansion, the valve stem changes length by varying input power. Total travel is no more than inches. As the length of the valve stem changes, its tip moves in and out of a seat, varying the gas flow. Unlike a gear train, precise control is achieved because dead band and hysteresis are eliminated. Except for its sapphire seat, the control valve, like the rest of the flow controller, is constructed entirely of type 316 stainless steel. Unlike some solenoid valves, which use less corrosion resistant magnetic materials in the process gas stream, the 260 series control valves are completely compatible with reactive and corrosive materials. 2.4 ELECTRONICS The electronics consist of a circuit board containing amplifier, linearizer, and detector bridge circuits. In addition, each controller board has a circuit which compares the detector output with an external command voltage, amplifies the difference, and powers the valve to balance the command signal. An RC network in this feedback circuit provides dynamic compensation for optimum stability and response. Figure 6 is the schematic diagram for the printed circuit board. p.4

7 _DESCRIPTION COVER The cover is made of plastic for the TN260 and TN261 and it is made of steel for the TN262. It is grounded to the flow base and the chassis ground connection. This, in conjunction with the roll-off and filter capacitors in the electronics, provides excellent EMI protection. p.5

8 _INSTALLATION INSTALLATION For maximum performance and service life, the instrument should be installed in a clean, dry atmosphere, relatively free of shock and vibration. Ambient temperature range for operation of the controller is 5 C to 43 C with a temperature coefficient of 0.1%/ C. Sufficient room for access to the electronics and plumbing should be provided to facilitate maintenance and removal for cleaning. Fitting caps should not be removed from the instrument until installation. 3.1 GAS CONNECTIONS Since the control valve in the instrument is not intended to provide positive shutoff, it is recommended that a separate shut-off valve be installed in series (upstream to eliminate a flow surge during turn-on, downstream to prevent back migration of contaminants into the control valve, or both). Figure 3: Swagelok Compression Gas Fitting Configuration Three types of fittings are available including VCR TM, VCO TM and Swagelok TM. Polished 300 series stainless steel tubing should be used to ensure a leak-tight system. Tubing should be pre-cleaned and polished to eliminate particulate contamination and ensure leak-tight operation. Insert the tubing into the fitting all the way to the shoulder. Tighten the nut finger tight. While holding the fitting body steady with a backup wrench, tighten the nut 1 1/4 turns. Do not use the case cover for leverage. After installation of the instrument and prior to its use, the plumbing system should be thoroughly leak-tested and purged. VCR, Swagelok and VCO are Trademarks of Crawford Fitting Co. 3.2 ELECTRICAL CONNECTIONS Refer to the appropriate electrical hookup diagram. POWER: Any ± 15 VDC power supply meeting the requirements as designated in the specifications may be used to energize the instrument. CONTROL SIGNAL: Any 0 to 5.0 VDC command voltage having a source impedance of 2500 ohms or less may be used. The input impedance of the flow controller is 0.5 mega ohm (minimum). A 4 to 20 ma current option is available. p.6

9 _INSTALLATION 3.0 OUTPUT INDICATION: Any 0 to 5.0 VDC meter with at least 1000 ohms/volt can be used to provide visual indication of the mass flow rate. Recorders, voltage dividers (for conversion to engineering units), and other instrumentation may be added, provided the total load impedance is at least 5000 ohms. 3.3 ENVIRONMENTAL REQUIREMENTS Refer to the specifications. TEMPERATURE: The instrument may be operated at any temperature between 5 C and 43 C, provided the gas and ambient temperatures are maintained equally. Since the indicated flow rate has a temperature coefficient of ± 0.1% per C, the user may want to calibrate the instrument at the actual operating temperature to maximize the measurement accuracy. PRESSURE: Flow controllers may be operated at any gas pressure up to 1135 kpa (150 psig). Since the indicated flow rate varies in direct proportion to specific heat (Cp), which varies differently with pressure and temperature depending upon the molecular structure of the gas, it is recommended that the instrument be calibrated at the actual operating pressure. NOTE: The pressure coefficient of ± 0.01% per psi generally applies to monatomic and diatomic gases only. The flow controllers, which can be pressurized to 10,500 kpa (1500 psig) without damage, have a maximum operating pressure of 1135 kpa (150 psig). The differential pressure (inlet to outlet) must be maintained within the specified range. Lower differential pressure ranges are available on special order. The flow controllers may be operated into a vacuum as long as the inlet pressure is 105 kpa (15 psig) or greater. Lower differential pressure ranges are available on special order. 3.4 CALIBRATION Each instrument is factory calibrated for the specific flow range and gas indicated on the nameplate. Standard factory calibration is within ± 10% and is referenced to standard temperature and pressure. The calibration for other gases can be approximated to ± 5% using the Conversion Factor Charts. Factory calibration utilizes the test gases shown in Appendix A, Gas Flow Conversion Factors. Calibration checks with other gases can show discrepancies of up to ± 5%. To obtain calibration accuracy of 1% after range change or for other gases, precision calibration equipment will be required. As detailed in the Adjustment and Calibration Procedures section, range changes can be made to within ± 15% by removing the inlet fitting and replacing the bypass. Fine tuning to the desired accuracy level can then be accomplished by adjusting the potentiometers on the printed circuit board in conjunction with a reference flow standard. p.7

10 _INSTALLATION 3.0 NOTE: In accordance with Semiconductor Equipment and Materials Institute Standard EI2-91, Standard Pressure and Temperature are defined as kpa (760 mm Hg) and 0 C respectively. 3.5 MOUNTING Two 8-32 UNC tapped holes are provided for mounting. The instrument is essentially insensitive to mounting position. p.8

11 _OPERATION OPERATING INSTRUCTIONS 4.1 INSTALLATION AND START-UP The interconnect cable should be tested separately for continuity, pin-to-pin shorts, and correct pin assignments per the electrical hook-up diagram. Attach the mating connector to the flow controller and secure it to the cover with two 4-40 x 5/ 8 inch long screws. Do not over-torque. After installation in the system and prior to operation, any reactive gas system should be thoroughly leak checked and then purged with dry nitrogen to eliminate the presence of air and moisture. A "cycle" purging technique is more effective in removing atmospheric contaminants than a simple continuous purge gas flow. To cycle purge, alternate the flow of purge gas with a pump down of the gas system to vacuum for several cycles. If vacuum is not available, reducing the pressure to kpa (zero psig) for several cycles should be adequate. Cycle purging helps remove contaminants from small, blind cavities in the system which constitute a virtual leak source. A more detailed procedure can be found in Appendix B. Apply ± 15 VDC power and allow a 30 minute warm-up time before pressurizing the system with process gas. If the indicated output does not settle to zero to within 1% full scale (or the level of zero desired), re-zero the instrument (see Adjustment Procedures) before proceeding. Once the zero has been verified, pressure may be applied. After establishing that no hazardous condition will be created by the venting of process gas, flow controller operation may then be verified over the complete operating range. If the flow output voltage is within ten Milli Volts of the setpoint, the flow controller is controlling properly. Check for this condition at the highest and lowest flows anticipated at both the highest and lowest input-output pressure differentials anticipated. 4.2 SAFETY FEATURES AND PRECAUTIONS Every effort has been made in the design of the instrument to provide safe, trouble-free operation. Key features include reverse power supply polarity protection, output over-voltage and short circuit protection, low component temperatures, and conformance to intrinsic-safety design criteria. The normally open valve automatically opens with power failure. The following precautions should be taken to prevent damage, minimize safety hazards, and maximize performance. 1. Use pre-cleaned tubing, free of particulate contamination. 2. Thoroughly leak test the entire system prior to operation (recommended level for elastomer seals is 1x10-9 atm cc/sec of Helium or less). 3. Use only clean, moisture-free (dry) gases. 4. Purge only with dry Nitrogen (or other inert gas) before and after breaking into the system. p.9

12 _OPERATION 4.0! WARNING! Proper leak check equipment and system plumbing must be available to leak check the controller after any mechanical adjustment has been performed on the valve. 5. DO NOT purge reactive gas systems with inert gases between runs unless it is required by the process. Even dry gases contain some amount of moisture which will result in contamination build-up. 6. ALWAYS command no flow when the gas supply is shut off. 7. Avoid installation of the instrument in close proximity to high sources of RF noise and/or mechanical vibration. If this is unavoidable, proven methods of instrumentation filtering, cable shielding, and/or shock mounting should be utilized. 4.3 OPERATING MODES In general, the instruments may be operated at any pressure and temperature that falls within the limits stated in the specification. Optimum performance, however, can be achieved and will prevail if the operating pressure and temperature are predetermined and controlled to a narrow range. Calibrating and "fine tuning" the instruments at the actual operating pressure, temperature and flow rates can significantly improve the performance characteristics. The instruments are factory calibrated at an ambient temperature of 23 C (± 3 C) and the inlet pressure set to the midpoint of the operating pressure range and corrected to standard conditions. Flow controllers are adjusted to pass full rated flow at the minimum inlet pressure, with kpa (0 psig) outlet pressure and shut down to less than 2% of full scale at the maximum inlet pressure. Response time is verified at both extremes. Celerity s thermally actuated valve is designed to be fully open when power is terminated. During normal process control sequencing, the Flow Controller will fully open when the flow is turned off by a solenoid valve in the line immediately downstream. As a result, when the solenoid valve is re-opened, the flow starts at a higher rate through the open valve in the controller until the automatic control stabilizes. (See Figure 8, Typical Start Transient). This initial flow surge can be advantageous in many process applications because it provides a more rapid transition from one gas mixture to another. In other processes, a gradual transition without an initial flow rate surge is more desirable. Systems can be wired so that the signal to open the solenoid valve causes the controller valve to close and then open the solenoid valve after a two-to-twenty second delay. (See Figure 8, Typical Soft Start Transient). If the solenoid valve is located downstream of the Flow Controller, there will be a small amount of trapped gas which will be released when the solenoid valve opens. This surge can be minimized by locating the controller and solenoid close together with a minimum amount of plumbing or eliminated entirely by locating the solenoid valve upstream of the controller. Flow controllers may be operated at inlet pressures of up to 1135 kpa (150 psig), provided the differential pressure is maintained within the 175 kpa to 380 kpa (10 to 40 psig) range and the outlet pressure of the flow controller is regulated to a relatively constant level. p.10

13 _OPERATION 4.0! WARNING! Never insert or unplug the connecting cable or the control valve leads with power on if there is a possibility that the ambient atmosphere might be explosive. Flow controllers can withstand pressure surges of up to 10,500 kpa (1500 psig) without damage, but are not designed to operate in a controlling mode above 1135 kpa (150 psig) inlet pressure. 4.4 ROUTINE AND PREVENTATIVE MAINTENANCE It is recommended that a routine maintenance schedule be established on each instrument in order to maximize its useful service life. This would include, as a minimum, cleaning and recalibration. It is recommended that calibration be done at least once a year. The optimum (or necessary) service period is dependent on usage, environmental conditions, gas corrosiveness, etc., and must be established by the user based upon historical experience in that particular application. The recommended steps for routine and preventative maintenance are as follows: 1. Purge the instrument with dry Nitrogen for a minimum of 30 minutes prior to removal from the system (See Appendix B for detailed Purge Procedure). 2. Verify the calibration of the flow metering section by comparison with a suitable reference standard or calibrator. 3. Operate the instrument in the control mode over its entire operating range (2 to 100% full scale) at the minimum and maximum inlet pressures of 175 kpa and 380 kpa (10 and 40 psig). Check response, stability and control resolution. 4. Remove the inlet and outlet fittings of elastomer sealed instruments and visually examine for signs of contamination. Examine the seals for any evidence of cracking, hardening, swelling or contaminant accumulation. Do not attempt to disassemble the TN260 unless replacement seals are available. 5. Based upon the results of steps 1 through 4 above either reinstall in the system (followed by a Nitrogen purge) or proceed to the applicable Cleaning, Adjustment and/or Calibration Procedure described in this manual. p.11

14 _MAINTENANCE MAINTENANCE, ADJUSTMENT AND RANGE CHANGE NOTE: The following instructions and procedures are intended for a laboratory bench top environment. Proper equipment and precautions should be used for any other system or environment. 5.1 CLEANING Should the instrument show symptoms of internal flow path contamination, it should be disassembled and cleaned. Elastomer seals on the fittings, sensor and valve should be examined for hardening, swelling, inflexibility, and/or contamination accumulation and should be replaced if any of these symptoms prevail relative to new and unused seals. The recommended sequence of solvents used for cleaning (either for flushing the assembled instrument or for soaking individual components in an ultrasonic cleaner) is as follows. For instruments used with all non-reactive, non-corrosive gases: Distilled water (2 to 3 minutes) Alcohol (2 to 3 minutes) Blow dry with dry Nitrogen or air. For instruments used with all highly reactive and corrosive gases: A solution of 2% HF, 8% HNO 3, and 90% de-ionized H 2 O (3 to 5 minutes) Distilled water (2 to 3 minutes) Alcohol (2 to 3 minutes) Blow dry with dry Nitrogen or air. Individual flow-path elements should be cleaned as follows: Fittings Remove the fittings from the base and clean individually Sensor Remove the P.C. Board from the assembly, then remove the two screws which secure the sensor assembly to the base. Run a. 18mm (.007 inch) diameter wire (stainless steel or piano) through the full length of the sensor tube 3 or 4 times. Replace the sensor on the base, torque to 15 in-lb., flush with solvent during the Bypass Cleaning Procedure as described below Bypass (See Figure 2, Bypass-Exploded View) If it is desired to change the range of a flow meter or controller beyond the electronics adjustment capabilities, it will be necessary to replace the bypass assembly to produce the nominal output of 5 ± 0.6 VDC at full scale flow. In addition, the valve may have to be adjusted. The bypass is a pre adjusted assembly located in the base, which can be removed and reinstalled with the use of a bypass torque p.12

15 _MAINTENANCE 5.0 wrench (see Mass Flow Maintenance Kits) or a screwdriver. New bypass assemblies may be installed with or without the Teflon retaining washer. Reinstall the bypass and torque to 25 in-lb. After the bypass assembly has been replaced or removed for cleaning, the flow meter section should be recalibrated per the procedures outlined in the Calibration section, since a calibration shift of as much as 10% may occur during this operation depending on the level of contamination Valve (See Figure 4) For minor contamination, the valve can be cleaned in place by flushing with solvent, purging with dry Nitrogen and then resetting the valve during test as described in the Valve Adjustment Procedure. TN260 TN261 TN262 (Low Flow) (Medium Flow) (High Flow) Figure 4: Mass Flow Controller Valves For severe contamination, the valve assembly can be removed from the base and cleaned. This is done as follows: 1. Unplug the valve from the P.C. Board. 2. Remove the screws which secure the valve flange to the base and pull the valve assembly out completely. 3. If further disassembly is necessary (due to the level of contamination), remove the screw at the bottom of the valve with a flat-tip screwdriver. If it is necessary to grip the valve body to break loose the screw, do so only on the lower valve stem below the O-ring. 4. Remove the sapphire seat by lightly tapping the valve on a solid surface. The seat may then be cleaned with a small cotton swab and flushed with p.13

16 _MAINTENANCE 5.0! CAUTION! Always make sure power is off before disconnecting or reconnecting the valve to the P. C Board. Freon DI water. The small ball on the end of the tube stem inside the valve may be similarly cleaned. 5. To flush the valve, spray upward into the bottom of the upright valve. NOTE: Excessive pressure against the stem ball may bend the tube. Under no circumstances should any metal or abrasive tool be used to clean the ball. This could scratch the ball and prevent the valve from reaching its rated shut-down of 2% of the flow range. 6. Replace the parts in the opposite order as they were removed, taking care to turn the cone shaped hold on one side of the sapphire seat toward the stem ball. It is recommended that the stem ball and sapphire seat be inspected with a microscope before reassembling to ensure that no cotton, lint, or other small particles remain on the ball or seat to prevent complete shutdown. Tighten the screw until it seats snugly against the sapphire seat. Excessive force may crack the seat. NOTE: Be sure to re-lubricate the O-ring with Halocarbon grease for Viton O-rings or Krylox grease for Kalrez O-rings prior to re-installation into the base. 7. Adjust the valve during test as described in the Valve Adjustment Procedure. After cleaning or replacement of the sensor, bypass or valve assemblies, the instrument must be adjusted and recalibrated against a suitable reference standard or calibrator to re-establish the original calibration and performance characteristics Adjustment and Calibration Procedures In order to maintain the original factory calibration and performance characteristics of the instrument, the following adjustments may be necessary during routine maintenance and servicing and will definitely be required after disassembly for cleaning and/or parts replacement. Calibration - Indicated Versus Actual Flow Each controller is factory calibrated for the specific flow and gases indicated on the nameplate. Standard factory calibration is within ± 1.0%. The calibration for other gases can be approximated to ± 5% by using the conversion factors shown in Appendix A. Factory adjustments should not be altered unless precision gas flow measuring equipment is available for calibration. Rota meters do not have sufficient accuracy for flow measurement calibration unless they have been specifically calibrated and the proper corrections are made for temperature and pressure. For access to the electronics, remove the two cover screws and carefully lift the cover from the assembly. If electrical adjustments are made with the cover removed and the P.C. Board exposed, be very careful not to break wires or create short circuits while the instrument is open. p.14

17 _MAINTENANCE 5.0 Recalibration may be accomplished as follows: 1. Thoroughly flush and dry the instrument to remove contaminants (see Cleaning Procedures). 2. Connect a source of gas to the inlet and a suitable flow standard to the outlet. If a volumetric calibrator is used, be sure to apply the proper density corrections to maintain the mass flow calibration of the flow meter. 3. Connect the power and indicator wires and allow a 30 minute warm-up period. 4. Disconnect the valve wires from the P.C. Board. The valve will open fully allowing flow meter operation. 5. Remove the outlet gas line and cap off the instrument to assure zero flow through the sensor. Adjust ZERO potentiometer R3 to make the indicator read zero (± 5mV). 6. Reconnect the outlet gas line and adjust the flow to the full-scale value. Set the output to read 5.00 VDC (± 5mV) at full-scale flow rate using the GAIN potentiometer R9. 7. Recheck zero as described in step Linearity adjustments are not normally required. After achieving calibration at zero and maximum flow, the midpoint calibration may be checked by setting the flow to make the indicator read 2.50 VDC. The calibrator should then measure half of the full range flow rate within 1% of full scale. If not, adjust the output to 2.50 VDC using the LINEARITY potentiometer R19. Although this adjustment is essentially independent, steps 5 and 6 should be repeated until all three points are within the desired calibration. 9. The flow meter section of the flow controllers can be calibrated with the instrument operating in the controller mode and using the setpoint control to dial in the desired flow rate. Adjustments should be made as in steps 5 through 8. When adjusting the gain and linearity potentiometers, the actual flow will change rather than the output voltage since the controller acts to control the output voltage to the commanded setpoint voltage. 10. If the instrument cannot be brought into calibration within the adjustment range of R3 or R9, the flow meter amplifier gain and/or bypass will have to be adjusted. This procedure is described in the Range Change section of this manual. 11. When using a test gas other than the intended usage gas, a correction factor equaling the ratio of the conversion factors of the two gases must be applied. See Appendix A, Gas Flow Conversion Factors, for further explanation. If there is not sufficient adjustment in the gain potentiometer to set 5.00 VDC at full flow, center the gain potentiometer and replace R8 with a resistor which will produce near 5.00 VDC at full flow and recalibrate following the procedures outlined in steps 6 through 9. p.15

18 _MAINTENANCE BYPASS ASSEMBLY (TN260 and TN261) If it is desired to change the range of a Flow Controller or flow meter beyond the electronics adjustment capabilities, it will be necessary to replace the bypass assembly to produce the nominal flow meter output of 5.0 ± 1 VDC at full scale flow. In addition, the valve may have to be adjusted or replaced. The bypass is a preadjusted assembly located in the base which can be removed and reinstalled with the use of a bypass torque wrench or a screwdriver. Each assembly is stamped with a coded number which identifies the range for which it was calibrated. After replacement or removal of the bypass for cleaning, the flow meter section should be recalibrated per the procedures outlined in the Calibration section. A calibration shift of as much as 10% may occur during this operation, depending on the level of contamination. TN262 If it is desired to change the range of this flow controller or flow meter, an adjustment may be made if the desired range is within the range of the installed bypass. Additionally, the valve assembly may have to be adjusted or replaced. A three digit number etched on the bypass is used to identify its range as follows: to 100 slm to 200 slm to 300 slm 1. If the desired range is outside of the range of the installed bypass, it will be necessary to replace it with the appropriate bypass assembly. This is done by removing the inlet fittings and using a 3/4 inch wide flat-blade screwdriver to turn the bypass assembly counter-clockwise until it becomes loose and can be removed. 2. If the desired range is within the range of the installed bypass assembly, only a simple adjustment is necessary. First, remove the bypass assembly as described above. Using a Phillips head screwdriver, adjust the center screw by turning it clockwise to locate the plug flush with the downstream end of the screen. 3. Thread the bypass back into the flow body and tighten it firmly against the shoulder. 4. Adjust the bypass to the desired full-scale flow rate by turning the adjusting screw clockwise to reduce the flow and counter-clockwise to increase the flow. Adjustment resolution for various high flow bypass sizes is as follows: slm per turn slm per turn slm per turn p.16

19 _MAINTENANCE 5.0! CAUTION! Press the screw firmly against the bypass nut during adjustment to ensure that the threads only engage the plug and not the support ring. Make sure that the screw does not thread out of the assembly during counter clockwise adjustment. 5.3 SENSOR REPLACEMENT If it is determined that either of the sensor elements is open or shorted to case, it will be necessary to replace the sensor assembly. This can be done by unsoldering the three sensor leads from the P.C. Board and removing the two screws which attach the sensor assembly to the base. The sensor assembly can then be removed and replaced. Before installing the new sensor element, resistance should be checked and measured as follows (at 24 C): Upstream (Brown to Green) Ru = 330± 13 ohms Downstream (Red to Green) Rd = ohms Isolation (All leads to sensor tube) 100 megaohms Examine the sensor seals (replace if necessary) and make sure they are seated with the open side toward the bottom of the assembly. Pressurize the base and check for leakage. Resolder the sensor leads to the circuit board (brown to brown, green to green, and red to red). 5.4 VALVE ADJUSTMENT (TN260 AND TN261) Valve adjustment is accomplished through the following procedure: 1. Plumb the inlet of the instrument to a regulated supply of the appropriate gas. Connect a reference flow meter in series, or monitor the flow as measured by the flow metering section of the instrument itself. 2. Remove the cover to permit access to the valve assembly. Plug the valve into the P.C. Board prior to applying power to the instrument. Starting with the valve mechanically open and the input command signal at zero, slowly apply inlet pressure to the controller to 380 kpa (40 psig). Mechanically close the valve by SLOWLY turning the adjusting nut clockwise until the flow is reduced to less than 2% of full scale. Cycle the valve from 0% to 100% then from 100% to 0% full scale to ensure consistent valve closure of less than 2% of full scale. 3. Set the inlet pressure to the minimum (5 psig for TN260 and 10 psig for TN261) and command 100% flow rate. Verify full-scale output. 4. If the valve does not close properly, the valve heater voltage may be increased by decreasing the resistance of R32.See Table 1. The heater voltage cannot exceed 10 VDC for TN260 or 15 VDC for TN261. If the valve still exhibits excessive leakage, the seat may be contaminated or damaged. Clean or replace the valve. 5. The valve may be replaced by disconnecting the valve heater wires from the P. C. Board and removing the two mounting screws which hold the valve in the base. Before replacing the valve, check the O-ring, seal for nicks, cuts, or damage and replace if necessary. After installing the valve and connecting the heater wires to the P.C. Board, adjust the valve per the preceding steps. 6. Leak check the controller. p.17

20 _MAINTENANCE 5.0! CAUTION! Do not exceed 10.0 VDC on the TN260 valve. R32 must be 5 ohms or greater to prevent severe valve damage (distortion or burn out). Overpowering the valve may reduce its life and reliability. Valve Closing Voltage See Note 1 and Note 3 Up to 5.0 VDC 5.0 to 6.0 VDC Table 1: R32 Selection Flow Controller TN260, TN261, TN ohms TN260, TN261, TN ohms R32 (114 Watt) See Note 2 and Note to 7.0 VDC TN260, TN261, TN ohms 7.0 to 8.0 VDC TN260, TN261, TN ohms 8.0 to 9.0 VDC TN260, TN261, TN ohms 9.0 to 1 l.0 VDC CAUTION: See Note ohms 11.0 to 13.0 VDC TN261, TN262 only 4.3 ohms 13.0 to 14.5 VDC TN261, TN262 only 3.0 ohms NOTE: 1. Measured voltage across valve required to close to less than 2.0% of rated flow at 40 psig inlet pressure. 2. Resistor values give approximately 20% power margin for valve closure. 3. A threshold circuit in the controller gives a minimum command of 1.5% full scale, thereby removing valve power when the gas supply has been shut off. p.18

21 _MAINTENANCE VALVE ADJUSTMENT (TN262 ONLY) Due to the complexity of the high-flow (TN262) valve, mechanical adjustments should not be attempted by other than qualified Celerity personnel. Inadequate shut-off can, however, be remedied in most cases by decreasing R32 to increase the valve power. See Table 1. A defective valve may be replaced by unplugging the valve wires from the line sockets and removing the four Allen screws which attach the valve assembly to the base. Installation of a replacement valve should be done with extreme caution, making sure that the O-rings are properly positioned, the valve leads are securely plugged into their mating sockets, and that the lead wires entering the electronic section are not pinched or strained as the valve assembly is being attached to the base. Dynamic Response Adjustment After replacement of a valve or recalibration of the unit, it may be necessary to readjust the feedback control circuit in order to optimize the dynamic response and stability performance. This involves reselecting R11 and R24 during transient tests to optimize the performance. While the steady state gain of the controller is essentially infinite (holding the error between the command setting and the flow meter output signal to zero over the entire flow range), the gain during a flow and/ or command setting transient is reduced to a low value determined by R24 and provides a slowly changing valve control voltage whose rate of change is determined by the time constant of C6, R24, and R22. This provides gradual change in flow rate, which is sensed, compared to the command and readjusted before the valve has a chance to overshoot or become oscillatory. Since the response time of both the sensor and valve depend highly on mechanical tolerances, flow rates, gas properties, electrical component values and tolerances, it is necessary to individually optimize the response of each unit by selecting the values of R11 and R24 during actual test. This is accomplished by setting the inlet pressure to 20 psi (or the known operating pressure), switching the command setting from 50 to 100% full flow and/or vice versa, and noting the response of the output signal to this change in command. The flow meter section, valve and maximum valve voltage must have been previously set. Optimizing the response characteristics at this pressure gives the best trade-off in performance since at lower pressure the response is slower. At higher pressure it is faster but more overshoot is present. Optimum response is achieved by the following procedures: 1. After calibrating the flow meter section and selecting the proper R32 for good valve closure, temporarily install R11 (430 Ω) and R24 (100K Ω) with resistance substitution boxes. p.19

22 _MAINTENANCE Operate the unit as a controller and alternately command 100% full flow, then 50% flow and observe the output and response. Reducing R11 reduces the time constant of the sensor speed-up circuit, which in turn reduces overshoot and more quickly dampens out oscillations following a step change in flow or pressure. Output ripple increases, however, due to the increased AC gain, and too low a value will result in output oscillation. p.20

23 _TROUBLESHOOTING 6.0! CAUTION! Always command zero flow when the gas supply is shut off. Failure to do so will result in excessive flow transients after the gas supply is turned "on" (See Electrical Hook-up Diagram). 6.0 TROUBLESHOOTING PROCEDURES 6.1 INITIAL TEST 1. Check setup and procedure against connection instructions given in the Installation section. Permanent damage to the instrument may result if purging procedures are not followed, or if line power is accidentally applied to the signal leads. 2. Test line cord for compliance with pin assignments and continuity from all wires to connect pins. Use a hipot tester to check for pin-to-pin shorts. During the test, flex the cable coming out of the connector to find intermittent shorts. 3. Check insulation resistance from Pin 2 to base. It should exceed 50 megaohms at 50 VDC. Pin 1 to case should measure less than 1 ohm. 4. If the unit under test is a flow meter, connect a source of gas (same as that for which the instrument is calibrated or equivalent test gas) to the inlet fitting. Apply power and allow a 30 minute warm-up period. With the appropriate inlet pressure applied, the actual flow (as measured by a suitable flow standard in series with the flow meter) should agree with the indicated flow within ± 2%. If the instrument is malfunctioning or cannot be recalibrated as previously described in the Adjustment and Calibration Procedure, check the appropriate symptom in the Troubleshooting Chart. 5. If the unit under test is a flow controller, connect a source of gas (same as that for which the instrument is calibrated or equivalent test gas) to the inlet fitting. Apply power and allow a 30 minutes warm-up period. With the appropriate inlet pressure applied, the output signal of the controller should follow the command setting (i.e., 50% of full scale at 2.50 VDC commanded voltage). Actual flow (as measured by a suitable flow standard in series with the controller) should follow the command setting and agree with the indicated flow of the controller. If the instrument is malfunctioning or cannot be recalibrated as previously described in the Adjustment and Calibration Procedure, check the appropriate symptom in the Troubleshooting Chart. NOTE: A threshold circuit in the controller ensures zero valve voltage whenever the commanded signal fails below 1.0%. It is not recommended that a failed electronic component be replaced, as component failures are usually caused by another problem in the device or in the system. It is recommended instead, that the flow controller be returned to the factory or other authorized Service Center for failure analysis and repair. p.21

24 _TROUBLESHOOTING 6.0 Table 2: General Troubleshooting Symptom Possible Cause Remedy No output Faulty meter No actual flow Sensor clogged Valve closed Electronic failure No input power Faulty power supply Read output at Pin 3 and Pin 2 directly with alternate meter Check pressures, valve positions, line or filter blockage See Cleaning Procedures See Valve section. Measure valve DC resistance (should be 410 ± 20 Ω ). If coil is open, replace coil or entire valve assembly. See Electronics Section Check for line power between appropriate pins at mating connector. Check input/output voltages (± 15 VDC, VDC) Maximum signal (approx. 200% of full scale) a. Indication correct, flow is high b. Indication erroneous Valve failed open Faulty power supply or command signal Open resistance element on sensor Electronics failure Check valve voltage as measured across valve wires. Valve should close when voltage rises between 6.0 and 10.0 VDC (TN260) or between 11.0 and 15.0 VDC (TN261 and TN262). Lower voltage indicates lack of closing command or electronic failure. Repair or replace electronics to 15.0 VDC indicates open valve heater. Measure valve DC resistance. It should be approximately 220 ohms. If open, replace valve. Check input/output voltages (± 15 VDC, VDC) Replace sensor See Electronics Section Table 3: Electronics Troubleshooting Symptom Possible Cause Remedy General failure or miscalculation Flow indication saturated (-0.7 or VDC) regardless of flow Power supply voltage off or nominal Bridge or sensor failure Component failure Check ± 15 VDC and ± 15 VDC. Check P.C. Board interconnect J2 Check sensor resistances, these should be 330 ± o C green to red and green to brown with power off. Voltage across BRN to RED should be 8.0 to 10.0 VDC and Pin 6 to circuit common should be ± 0.35 VDC. Check zero pot R3, gain pot R9, other components and solder joints Valve drive open or driven off (0 VDC). Valve drive saturated (>20 VDC) Valve drive transistor Q3 open or Q2 shorted. Q3 short, Op-amp (U1) failed. Check Q2, Q3 and other components; replace as required Replace if necessary, or replace P.C. Board assembly p.22

25 _TROUBLESHOOTING 6.0! CAUTION! Always command zero flow when the gas supply is shut off. Failure to do so will result in excessive flow transients after the gas supply is turned "ON" (See Electrical Hook-up Diagram). Symptom Possible Cause Remedy All circuits functional, but out of calibration Controls, but output voltage does not agree with pot setting Table 3: Electronics Troubleshooting (Continued) Contamination, or as a result of cleaning or repairing VDC pot supply off nominal Large input voltage offset in Op-amp(U1) Adjust Check VDC reference supply. Read just as necessary Check U1. Replace as necessary, or replace P.C. Board Table 4: Valve Troubleshooting Symptom Possible Cause Remedy Signal offset at zero flow Valve fails to close Electronics not adjusted Contamination Open valve heater Valve failed open Electronics failure Mechanical damage from over-pressure or other cause Operation on wrong gas (e.g., unit adjusted for Argon may not shut off completely on Hydrogen) Contamination See Adjustment Procedures See Cleaning Procedures Verify by removing the case and measuring dc resistence of the valve with power off. It should be 80 ± 10 Ω for TN260 and 120 ± 10 Ω for TN261/262. If the heater is open, replace the valve. Refer to "General Troubleshooting Table" on the previous page. Use the same remedy as the Valve failed open under possible cause. See Electronics Section Adjust or replace valve Test on proper gas or mechanically readjust valve See Cleaning Procedures Valve fails to open Electrically commanded closed or pot shorted Check command signal (Pin A and Pin B) and pot. Check for electronic failure. Valve controls at flow rates, but not at minimum Valve oscillates or hunts Clogged inlet or outlet screens appearing as closed valve Contamination Erosion or corrosion Improper adjustment or inadequate drive Erratic pressure regulator Improper system dynamics due to excessive inlet presure Improper dynamics in electronics Clean inlet and outlet filter fittings See Cleaning Procedures. Replace valve See Adjustment Procedures Replace regulator Reduce upstream pressure regulator setting Check for failed resistor or capacitor. See Dynamic response adjustment procedure. p.23

26 _TROUBLESHOOTING 6.0 Table 5: Part Numbers for Replaceable Spare Parts Descripti on Instrument TN260 TN261 TN262 TN360 TN361 TN362 Bypass 316 SS xxx Reactive Gas Cover Assembly Standard Flat Ribbon Circuit Board Assembly x x x x Fittings, Inlet 1/8-inch Swagelok (316 SS) 1/4-inch Swagelok (316 SS) 1/4-inch VCR (316 SS) 3/8-inch Swagelok (316 SS) 3/8-inch VCR (316 SS) Fittings, Outlet 1/8-inch Swagelok (316 SS) SS ST SS ST 1/4-inch Swagelok (316 SS) SS ST SS ST SS ST SS ST 1/4-inch VCR (316 SS) SS-4-VCR- 1- SS-4-VCR- 1- SS-4-VCR- 1- SS-4-VCR- 1-3/8-inch Swagelok (316 SS) SS ST SS SS ST SS /8-inch VCR (316 SS) SS-8-VCR SS-8-VCR p.24

27 _TROUBLESHOOTING 6.0 Table 5: Part Numbers for Replaceable Spare Parts (Continued) Descripti on Instrument TN260 TN261 TN262 TN360 TN361 TN362 O-Rings Outlet (Viton) Outlet (Neoprene) Outlet (Kalrez) Inlet (Viton) Inlet (Neoprene) Inlet (Kalrez) Sensor All flow controllers and flow meters use the following sensors and seals. Viton Assembly with seal = Seals only = Neoprene Assembly with seal = Seals only = Kalrez Assembly with seal = Seals only = Table 6: Part Numbers for Replaceable Spare Parts Description Valve, W/Viton Seals (Non- Corrosive Gases Only) 10 to 100 sccm (316 SS) 101 to 500 sccm (316 SS) 1 to 2 slpm (316 SS) 3 to 5 slpm (316 SS) Instrument TN260 TN261 TN262 TN360 TN361 TN362 N/A N/A N/A slm (H 2 /N 2 ) to 50 slm (all but NH 3 ) 60 to 100 slm (all but NH 3 ) 110 and up (all but NH 3 ) Valve, W/ Neoprene Seals N/A N/A N/A p.25

28 _TROUBLESHOOTING 6.0 Table 6: Part Numbers for Replaceable Spare Parts (Continued) Description Instrument TN260 TN261 TN262 TN360 TN361 TN362 (NH 3 Only) to 100 sccm (316 SS) 101 to 500 sccm (316 SS) 1 to 2 slpm (316 SS) to 5 slpm (316 SS) to 50 slm to 100 slm slm and up Valve, W/Kalrez Seals N/A N/A N/A 10 to 100 sccm (316 SS) 101 to 500 sccm (316 SS) 1 to 2 slpm (316 SS) 3 to 5 slpm (316 SS) Valve Seals Only N/A N/A N/A Inner (Viton) Inner (Neoprene) Inner (Kalrez) Outer (Viton) Outer (Neoprene) Outer (Kalrez) Seat (Viton) Seat (Neoprene) Seat (Kalrez) p.26

29 _TROUBLESHOOTING 6.0 Table 6: Part Numbers for Replaceable Spare Parts (Continued) Description Base (Viton) Base (Viton) Base (Neoprene) Base (Neoprene) Bypass (Viton) Bypass (Neoprene) Instrument TN260 TN261 TN262 TN360 TN361 TN Table 7: TN260 Series Mass Flow Controller Specifications Specifications TN260 TN261 TN262 Performance Full Scale N2 equivalent ranges 0.2 sccm to 10 sccm 200 sccm to 10 slm 1.2 slm to 30 slm 0.4 sccm to 20 sccm 300 sccm to 15 slm 2.0 slm to 50 slm 0.6 sccm to 30 sccm 400 sccm to 20 slm 4.0 slm to 100 slm 1.0 sccm to 50 sccm 6.0 slm to 150 slm 2.0 sccm to 100 sccm 8.0 slm to 200 slm 4.0 sccm to 200 sccm 6.0 sccm to 300 sccm 10.0 sccm to 500 sccm 20 sccm to 1000 sccm 40 sccm to 2000 sccm 60 sccm to 3000 sccm 100 sccm to 5000 sccm Accuracy ± 1.0% ± 1.0% ± 2.0% Repeatability ± 0.2% ± 0.2% ± 0.2% Linearity ± 0.5% ± 0.5% ± 1% Response Time (Typical) 6 seconds to within ± 2% of setpoint 10 seconds to within ± 2% of setpoint 30 seconds to within ± 2% of setpoint p.27

30 _TROUBLESHOOTING 6.0 Table 7: TN260 Series Mass Flow Controller Specifications (Continued) Specifications TN260 TN261 TN262 Pressure Drop 10 to 40 psid 15 to 40 psid 20 to 40 psid for>200 slm 30 to 60 psid for 200 slm and up Operating Gas Pressure 30 psig optimum 30 psig optimum 40 psig optimum 150 psig maximum 150 psig maximum 150 psig maximum 500 psig proof 500 psig proof 500 psig proof Pressure Coefficient 0.01% / kpa (0.07%/psi) 0.01% / kpa (0.07%/ psi) 0.01% / kpa (0.07%/ psi) Temperature Range 5-43 ºC 5-43 ºC 5-43 ºC Temperature Coefficient ± 0.1%/º C ± 0.1%/º C ± 0.1%/º C Warm-up Time 30 minutes 30 minutes 30 minutes Attitude Sensitivity Insensitive to attitude Insensitive to attitude Insensitive to attitude Environmental Pressure >100 Torr (2 psia) >100 Torr (2 psia) >100 Torr (2 psia) Humidity 0-90% Relative humidity 0-90% Relative humidity 0-90% Relative humidity Non-condensing Non-condensing Non-condensing Electrical Input Power +15 VDC ± 4%, 25 ma maximum +15 VDC ± 4%, 25 ma maximum +15 VDC ±4%, 25 ma maximum +15 VDC ± 4%, 180 ma maximum +15 VDC ± 4%, 180 ma maximum +15 VDC ±4%, 180 ma maximum Power Consumption 4.0 watts maximum 4.0 watts maximum 4.0 watts maximum Command Signal 0.1 to 5 VDC (2.5 K maximum source) 0.1 to 5 VDC (2.5 K maximum source) 0.1 to 5 VDC (2.5 K maximum source) Minimum Load Resistance Supply Voltage ± 12 VDC to ± 18 VDC ± 12 VDC to ± 18 VDC ± 12 VDC to ± 18 VDC Input/Output Signal 0 to 5 VDC 0 to 5 VDC 0 to 5 VDC Connection Type Card Edge Card Edge Card Edge Mechanical Valve (Thermal expansion) Normally Open Normally Open Normally Open Materials 316 Stainless Steel 316 Stainless Steel 316 Stainless Steel Fittings 2S (1/8-inch Swagelok ) 4S (1/4-inch Swagelok ) 6S (3/8-inch Swagelok ) 4S (1/4-inch Swagelok ) 4V (1/4-inch VCR ) 6V (3/8-inch VCR ) p.28

31 _TROUBLESHOOTING 6.0 Table 7: TN260 Series Mass Flow Controller Specifications (Continued) Specifications TN260 TN261 TN262 4V (1/4-inch VCR ) 4VO (1/4-inch VCO ) 6VO (3/8-inch VCO ) 4VO (1/4-inch VCO ) 6S (3/8-inch Swagelok ) 6V (3/8-inch VCR ) Mounting Insensitive to mounting position Insensitive to mounting position Insensitive to mounting position Weight 1.1lbs (500 gms) 2.1 lbs (954 gms) 5.0 lb. (2.27 Kgs) Dimensions (See outline drawing) VCR, VCO & Swagelok are Trademarks of Crawford Fitting Co. Table 8: TN360 Series Mass Flow Meter Specifications Specifications TN360 TN361 TN362 Performance Full scale N 2 equivalent ranges 0 sccm to 10 sccm 0 sccm to 10 slm 0 slm to 30 slm 0 sccm to 20 sccm 0 sccm to 15 slm 0 slm to 50 slm 0 sccm to 30 sccm 0 sccm to 20 slm 0 slm to 100 slm 0 sccm to 50 sccm 0 slm to 150 slm 0 sccm to 100 sccm 0 slm to 200 slm 0 sccm to 200 sccm 0 sccm to 300 sccm 0 sccm to 500 sccm 0 sccm to 1000 sccm 0 sccm to 2000 sccm 0 sccm to 3000 sccm 0 sccm to 5000 sccm Accuracy ± 1.0% ± 1.0% ± 2.0% Repeatability ± 0.2% ± 0.2% ± 0.2% Linearity ± 0.5% ± 0.5% ± 1% Response Time (Typical) 6 seconds to within ± 2% of setpoint 6 seconds to within ± 2% of setpoint 10 seconds to within ± 2% of setpoint Pressure Drop 0.5 psid at full scale 0.5 psid at full scale 0.5 psid at full scale Operating Gas Pressure 500 psig maximum 500 psig maximum 500 psig maximum 1500 psig proof 1500 psig proof 1500 psig proof p.29

32 _TROUBLESHOOTING 6.0 Table 8: TN360 Series Mass Flow Meter Specifications (Continued) Specifications TN360 TN361 TN362 Pressure Coefficient 0.01% / kpa (0.07% psi) 0.01% / kpa (0.07% psi) 0.01% / kpa (0.07% psi) Temperature Range 5-43 C 5-43 C 5-43 C Temperature Coefficient ± 0.1% / C ± 0.1% / C ± 0.1% / C Warm up Time 30 minutes 30 minutes 30 minutes Attitude Sensitivity Insensitive to attitude Insensitive to attitude Insensitive to attitude Environmental Pressure >100 Torr (2 psia) >100 Torr (2 psia) >100 Torr (2 psia) 0-95% Relative Humidity, Non-condensing 0-95% Relative Humidity, Non-condensing 0-95% Relative Humidity, Non-condensing Electrical Input Power +15 VDC ± 4%, 25 ma maximum +15 VDC ± 4%, 25 ma maximum +15 VDC ± 4%, 25 ma maximum +15 VDC ± 4%, 180 ma maximum +15 VDC ± 4%, 180 ma maximum +15 VDC ± 4%, 180 ma maximum Power Consumption 1.5 watts maximum 1.5 watts maximum 1.5 watts maximum Command Signal N/A N/A N/A Ω Ω Ω Minimum Load Resistance Supply Voltage ± 12 VDC to ± 18 VDC ± 12 VDC to ± 18 VDC ± 12 VDC to ± 18 VDC Input / Output Signal 0 to 5 VDC 0 to 5 VDC 0 to 5 VDC Connection Type Card Edge Card Edge Card Egde Mechanical Valve (Thermal expansion) N/A N/A N/A Materials 316 Stainless Steel 316 Stainless Steel 316 Stainless Steel Fittings 2S (1/8-inch Swagelok TM ) 4S (1/4-inch Swagelok TM ) 6S (3/8-inch Swagelok TM ) 4S (1/4-inch Swagelok TM ) 4V (1/4-inch VCR TM ) 6V (3/8-inch VCR TM ) 4V (1/4-inch VCR TM ) 4VO (1/4-inch VCO TM ) 6VO (3/8-inch VCO TM ) 4VO (1/4-inch VCO TM ) 6S (1/8-inch Swagelok TM ) 6V (1/8-inch VCR TM ) Mounting Insensitive to mounting Insensitive to mounting Insensitive to mounting Weight 1.0 lbs (454 gms) 2.0 lbs (907 gms) 4.75 lbs (2015 kgs) Dimensions (See outline drawing) VCR, VCO & Swagelok are Trademarks of Crawford Fitting Co. p.30

33 _TROUBLESHOOTING 6.0 Figure 5: Printed Circuit Board Assembly p.31

34 _TROUBLESHOOTING 6.0 Figure 6: Mass Flow Controller Outline Drawing p.32

35 _TROUBLESHOOTING 6.0 Figure 7: Printed Circuit Board Schematic Diagram p.33

36 _TROUBLESHOOTING 6.0 Table 9: Flow Controller and Flow Meter Dimensions TN260/TN360 Fittings H H1 W W1 W2 L L1 L2 L3 L4 L5 S 2S in mm S in mm CO in mm V in mm TN261/TN361 Fittings H H1 W W1 W2 L L1 L2 L3 L4 L5 S 4S in mm V in mm VO in mm S in mm V in mm TN262/TN362 Fittings H H1 W W1 W2 L L1 L2 L3 L4 L5 S 4V in mm S in mm V in mm VO in mm Fitting Suffix Key 2S = 118-inch Swagelok 4S = 114-inch Swagelok 4V = 114-inch VCR 4VO = 1/4-inch VCO 6S = 3/8-inch Swagelok 6V = 3/8-inch VCR 6VO = 3/8-inch VCO p.34

37 _TROUBLESHOOTING 6.0 See Figure 8 for R2 values Typical Start Transient Typical Soft Start Transient Control Setting Control Setting Solenoid opening surge occurs only if solenoid valve is downstream of controller FLOW RATE (% of range) FLOW RATE (% of range) SOFT START WIRING DIAGRAM CONNECTOR (AMP) PINS (AMP) KEYING PLUG +15 VDC -15 VDC GND COM FLOW CONTROLLER F Eo VDC +15 VDC -15 VDC GND 5K POT 0 to 5.0 VDC OUTPUT Ec 5K POT COM Ev ON/OFF SWITCH TO 24 VDC OR 24 VAC SOL & RELAY MUST HAVE SAME COIL VOLTAGE Figure 8: Soft Start Diagrams p.35

38 _APPENDIX A GAS FLOW CONVERSION FACTORS APPENDIX A This document is intended to help select a conversion factor relative to the test gas that closely matches the sample gas. EXAMPLE: Sample Gas Ammonia (NH 3 ) C.F. = Test Gas Nitrous Oxide (N 2 O) C.F. = Conversion Factor Relating To Test Gas 0.719/0.709 = 101.4% Once a test gas conversion factor is selected (101.4%), divide the desired rate of flow by that percentage to obtain the adjusted flow rate for the standard unit (unit calibrated for the test gas). 1.0 EXAMPLES Example 1: (Using C.F. relative to test gas required calb: 1000 sccm Bromine (Br2) (C.F. = 0.808) A) Using N 2 standard and N 2 test gas 0.808/1.00 = for 1000 sccm Br2 need 1000/0.808 = 1238 N2 Use a 1500 sccm standard, VO of standard (1238/1500) x 5V = 4.13V or 82.5% F.S B) Using N 2 O standard and N 2 O test gas (C.F = 0.709) /0.709 = for 1000 sccm Use A 1000 sccm standard, VO of standard (877/1000) X 5v = 4.38v or 87.6% F.S Example 2: Required calb: 1000 sccm 10% Argon 90% CO 2 (C.F. relative to N 2 = 0.777) A) Using N 2 O standard and N 2 O test gas (C.F = 0.709) 0.777/0.709 = for 1000 sccm 10% Ar 90% CO 2 need 1000/1.096 = N 2 O Use a 1000 sccm standard VO of standard (912.4/1000) X 5v = = 91.2% Full scale test standard = 91.2%/2 = 45.6% Linearity test standard p.36

39 _APPENDIX 100% 9 F.S) = 109.6% 91.2% Linearity = 50% 45.6% B) Alternative method using N2O standard and test gas (C.F. = 0.709) 0.777/0.709 = X 100% (F.s) = 109.6% = X 50% (Lin) = 100% (F.S) = 100% 100% 50% (Lin) = 54.8% 50% NOTE: Assuming actual flow of test standard per calibration sticker is F.S.and linearity. 2.0 DETERMINING MASS FLOW CONVERSION FACTORS The ratio of a flow W 1 for a particular gas, to the flow W 2 of a different gas which will produce the same output voltage in a flowmeter or controller is equal to the ratio of their respective correction factors. This relationship is shown in Equation 1below: C1/c2 = W1/w2...Equation 1 Equation 2 shows the relationship between the properties of a gas and its rate of flow in standard cubic centimeters per minute for equal output voltages: W = Kn/ ρcp...equation 2 p.37

40 _APPENDIX A ρ Cp is the specific heat in cal/g-c is is the density of the gas at o c in g/liter, and n is a correction factor for the molecular structure of the gas. the values of n are lised in Table 1 for a particular flow meter or controller, k is a constant. Substituting Equation 2 into Equation 1 yields the following relationship: (C 1 /C 2 ) = (KN 1 /p 1 Cp 1 ) / (KN 2 /p 2 Cp 2 )...Equation 3 If we define both the conversion factor and the correction factor n, for the gas Nitrogen to be 1.000, Equation 3 can be reduced to the following: C = (pn 2 CpN 2 )N 1 / (pcp 1 )....Equation 4 By dropping the subscript 2 and replacing N 2 and CpN 2, the density and specific heat respectively of Nitrogen, with the actual values, we have an equation for claculating the flow conversion factors: C = ( /pcp) x N...Equation 5 ρ Document PS-1064t lists the conversion factors for commonly used gases as derived from Equation 5. Substituting the flow range and conversion factor of the factory calibrated gas and the conversion factor of a different gas into Equation 1 yields the flow range for the different gas. Example: A flow meter is callibrated for H2 and the flow rate is 5000 sccm for 5.00 VDC output. The flow rate for Nitrous Oxide at 5.00 VDC output is: Document PS-1064t lists the conversion factors for insert limiter for commonly used gases. When calculating the conversion factor for a limiter option column, the following equations should be used: Flow psig = 4 slm x Flow Φ ORIFICE = Flow Φ X (Φ ORIFICE /0.0145) /0.709 = 5000/W W = (0.709 x 5000)/1.01 = 3510 sccm When calculating the conversion factor for a mixture of two or more gases, the following equations should be used. The equivalent density is given by the relationship: p = (W 1 /W 2 ) p 1 + (W 2 /W T ) p (W n /W T ) p n...equation 6 p.38

41 _APPENDIX A Where: W 1 is the flow of gas # 1 W 2 is the flow of gas # 2 W n is the flow of gas # n W t is the total flow N 1 is the molecular C.F of gas # 1 N 2 is the molecular C.F of gas # 2 N n is the molecular C.F of gas # n ρ ρ ρ 1 is the density of gas # 1 2 is the density of gas # 2 N is the density of gas # n Cp 1 is the specific heat gas # 1 Cp 2 is the specific heat gas # 2 Cp n is the specific heat gas # n The equivalent specific heat is given by equation: Cp = F 1 Cp 1 + F 2 Cp F n Cp n....equation 7 where F1 = (W 1 p 1 ) / (W T p), F2 = ((W 2 p 2 ) / (W T p)) +,,,,,Fn = (W n p n ) / W T p...equation 8 The equivalent value of N is: N = (W 1 /W T )N 1 + (W 2 /W T ) (W n /W T )N...Equation 9 p.39

42 _APPENDIX A For gas mixtures, the values Equation 5. ρ, Cp and N from Equations 6, 7 and 9 are used in Combining numbers 5 through 9 results in the following Equations: C = ((W 1 /W T )N 1 + (W 2 /W T )N (W n /W t )N n ) (W 1 /W T )p 1 Cp 1 = (W 2 /W T )p 2 Cp (W n /W t )p n Cp n Equation 10 (W 1 /W T )N 1 + (W 2 /W T )N (W n /W T )N n C = (W 1 /W T ) x (N 1 /C T ) + (W 2 /W T ) x (N 2 /C T ) +...+(W n /W T ) x (N n /C T ) Equation 11 Example: 10% Argon 90% CO 2 Let Argon Be Gas #1 & CO 2 Gas # ((10/100) x (90/100) x 0.94) C.F. = ((10/100) x x ) + ((90/100) x x )) ( ) (0.947) C.F. = C.F. = relative to N2 p.40

43 _APPENDIX A 3.0 MIX GAS CONVERSION FACTOR to N 2 EQUIVALENT The following equation represents the calculation necessary to determine the conversion factor to N 2 equivalent where : Constant= MF 1 = Molecular Factor of Gas 1 DEN 1 = Density of Gas 1 SH 1 = Specific 25 C of Gas x ((% of Gas 1 x MF 1 ) + (% of Gas 2 x MF 2 ) + (% of Gas 3 x MF 3 )) (% of Gas 1 x Den 1 x SH 1 )+(% of Gas 2 x Den 2 x SH 2 )+(% of Gas 3 x Den 3 x SH 3 ) NOTE: 1) The percentage of gases must add up to 100% when using formula % is stated in decimals. e.g - 15% = ) If there are more than three gases, insert additional data of GAS. 3) If there are less than three, do not put any data in for three. Instructions: 1) Find MF for each Gas from Table 1 of PS-1064 (PS 1064 T might have factor installed later) Monatomic Gases (gases with only one molecule) e.g. AR, HE, NE etc. = 1.01 Diatomic Gases (gases with two molecules ) e.g. CO, N 2, O 2, NO etc. = 1.00 Triatomic Gases (gases with three molecules) e.g. CO 2, N 2 O, SO 2 Etc. = 0.94 Polyatomic Gases (gases with four or more molecules) e.g. NH 3, PH 3, CH 4 etc. = ) FIND DEN for each gas from PS-1064T Column Headed "DENSITY" 3) FIND SH for each gas from PS-1064T Column Headed "Specific 25 C 4) Use formula above: Step 1. Multiply % of Gas times MF for each gas Step 2. Add the results for each MF Gas Step 3. Multiply that result by the Constant Step 4. Multiply the % of Gas times it's DENSITY times It is SPECIFIC HEAT for each gas. Step 5. Add those results together Step 6. Divide the result from Step 3 by the result from Step 5. p.41

44 _APPENDIX A 4.0 CONVERSION TABLE Psi (Lbs/in 2 ) X Mmhg (0 o c) 0 o c X = Inches of Hg Psi (Lbs/in 2 ) X = Inches of Hg Hg X ( ) = Lbs/sq inches (psi) Standard pressure in absolute unit = psi (Atmosphere) = 760 Mmhg = In. of Mercury Atmospheric pressure (Sea Level, 0 o c) = One atmosphere Inches of H 2 0 (4 o c) X = Lbs/sq Inch (Psi) Cubic feet per hour X = Liters per minute Cubic feet per minute X = Liters per minute (lpm) Slpm (Liters/min.) X = Cfm Cubic centimeter X = Liters Liters X 1000 = Cubic centimeters Cubic feet/minute X 60 = Cubic feet/hour C = 5/9 (F-32 ) F = 9/5C Torr = 1 0 c = atmosphere 1 Torr X = psi Psi X = Torr of Mmhg Lb/hour X L/minute p.42

45 _APPENDIX A Table 10: Values For The Molecular Correction Factor Types of Gases N Monatomic Gases (E.g. Argon, Helium, Xenon) Diatomic Gases (E.g. Carbon Monoxide, Nitrogen, Oxygen, Nitric Oxide) Triatomic Gases (E.g. Carbon Dioxide, Nitrous Oxide, Sulfur Dioxide) Polyatomic Gases (E.g. Ammonia, Arsine, Diborane, Ethane, Methane, Phosphine) NOTE: Standard pressure is defined as 760 mmhg (14.7 psig). Standard temperature is defined as 0 C. Table 11: Special Gases (Most Commonly Used) Name Plate Gas Range Operating Pressure CLF3 N/A 3-12 psi C4F8 N/A 3-12 psi BCL3 N/A 3-12 psi SICL4 N/A 3-12 psi WF6 N/A 3-12 psi HF N/A 3-12 psi C4H6 N/A 3-12 psi NOTE: If other gases are used, other than the list above, please refer to PS- 1064T. p.43

46 _APPENDIX A Conversion Factor Rel. To Cal Cal Dynamic Heat Specific Specific Response Cpx10 3 Heat 25 C Code Gas Symbol Test GasTest Gas N2 Test Gas (J/k. mol) Temp ( c) Density Sug. Seal Cp (Cal/ C Mat. g C) Std Cal Press (Psid) Molecular Factor 25 Acetylene C2H2 C2H N V 10 to Air - N N V 10 to Allene (Propadlene) C3H4 C2H Ar V 10 to Ammonia NH3 N2O N N 10 to Argon Ar Ar Ar V 10 to Arsine AsH3 N2O N2O V 10 to Acetaldehyde CH3CH0 C2H N2O KZ 3 to Benzen C6H6 C2H N V 3 to Boron Tribromide BBr3 C2H SF KZ 3 to Boron Trichloride BCl3 C2H SF KZ 3 to Boron Trifluoride BF3 C2H N2O KZ 10 to Bromine Br2 N2O SF V 10 to Bromine Pentafluoride BrF5 SF SF KZ 3 to Bromine Trifluoride BrF3 C2H SF KZ 10 to ,3-Butadiene C4H6 SF N2O V 6 to n-butane n-c4h10 SF ,255 N2O V 6 to Butene C4H8 SF ,294 N2O V 6 to Butene CIS C4H8 SF N2O V 6 to Butene TRANS C4H8 SF N2O V 6 to Carbon Dioxide CO2 N2O N2O V 10 to Carbon Disulfide CS2 C2H N2O V 10 to Carbon Monoxide CO N N V 10 to Carbon Tetrachloride CCI4 SF SF V 3 to Carbonyl Fluoride COF2 C2H N2O KZ 10 to Carbonyl Sulfide COS N2O N2O KZ 10 to Chlorine CI2 N2O N2O V 10 to Chlorine Trifluoride CIF3 C2H N2O KZ 3 to Chloroform CHCI3 C2H SF V 3 to Cyanogen C2N2 C2H N2O V 10 to Cyanogen Chloride CICN C2H N2O V 10 to Cyctopentance C5H10 C2H N2O KZ 10 to Cyctopropane C3H6 C2H N2O V 10 to Deuterim D2 N He V 10 to Diborane B2H6 C2H N V 10 to Dibromodiflouro methane CBr2F2 SF SF V 3 to Dibromomethane CH2Br2 C2H SF V 10 to Dichloromethylsilane (CH3)2SI CI2 SF SF KZ 3 to Dichlorosllane SiH2Cl2 C2H SF KZ 3 to p.44

47 _APPENDIX A Conversion Factor Rel. To Cal Cal Dynamic Heat Specific Specific Response Cpx10 3 Heat 25 C Code Gas Symbol Test GasTest Gas N2 Test Gas (J/k. mol) 166 Trans1,2- Dichloroethylene Temp ( c) Density Sug. Seal Cp (Cal/ C Mat. g C) Std Cal Press (Psid) Molecular Factor C2H2CI2 SF SF V 10 to Dlfluoromethane CH2F2 C2H N2O V 10 to Ethane C2H6 C2H C2H V 10 to Ethanol C2H60 C2H N2O V 3 to Ethyl Acetylene (1- Butyne) C4H6 SF N2O V 3 to Ethylamine C2H5NH2 SF N2O V 10 to Ethyl chloride C2H5CI SF N2O V 3 TO Ethylene C2H4 C2H C2H V 10 to Ethylene Oxide C2H4O C2H N2O KZ 3 to Fluorine F2 N Ar V 10 to Fluroform (Freon-23) CHF3 C2H N2O V 10 to Trichlorofluoromethane Freon-11 CCI3F SF SF V 3 to Dichlorodiflouro methane Freon-12 Cholrotriflouromethane Freon-13 Bromotriflouromethane Freon-13B1 Carbon Tetraflouride Freon-14 Dichlorodiflouro methane Freon-21 Chlrodiflouromethane Freon-22 Trichlorotriflouroethane Freon-113 1,2-Dichlorotetraflouro ethane Freon-114 Chloropentaflouro ethane Freon-115 Hexafluoroethane Freon-116 Octaflourocyclobulane Freon-C318 CCI2F2 SF SF V 10 to CCIF3 SF SF V 10 to CBrF3 SF SF V 10 to CF4 CF CF V 10 to CHCI2F C2H SF KZ 3 to CHCIF2 C2H N2O KZ 10 to CC12FCC IF2 SF SF V 3 to C2CI2F4 SF SF V 3 to C2CIF5 SF SF V 10 to C2F6 SF6 ** SF KZ 10 to C4F8 SF SF V 6 to Freon-152A C2H4F2 C2H SF N 10 to Pentaflouroethane Freon-125 C2HF5 SF SF V 10 to Tetraflourethane Freon-134A C2H2F4 C2H SF V 10 to Germane GeH4 C2H N2O V 10 to Germanium Tetrachloride GeCI4 SF SF V 3 to p.45

48 _APPENDIX A Conversion Factor Rel. To Cal Cal Dynamic Heat Specific Specific Response Cpx10 3 Heat 25 C Code Gas Symbol Test GasTest Gas N2 Test Gas (J/k. mol) (CH3)3SI- 182 Hexamethyl Dlsiloxane O- SI(CH3)3 Temp ( c) Density Sug. Seal Cp (Cal/ C Mat. g C) Std Cal Press (Psid) Molecular Factor SF SF KZ 1 to Helium* He He He V 10 to Isobutane CH(CH3)3 SF N2O V 6 to Isobutylene C4H6 SF N2O V 6 to Isopropanol C3H7OH SF N2O V 3 to Kryplon Kr Ar N2O V 10 to Methane CH4 N2O N V 10 to Methanol CH3OH C2H C2H V 10 to Methylacetylene (Propyne) C3H4 C2H Ar V 10 to Methylamine CH3NH2 C2H C2H KZ 10 to Methyl Bromide CH3Br C2H N2O KZ 6 to Methyl Chloride CH3CI C2H N2O V 10 to Methyl Fluoride CH3F N2O C2H V 10 to Methyl Mercaptan CH3SH C2H N2O V 6 to Methyl Trichlorosilane (CH3)SIC L3 SF SF KZ 3 to Molybdenum Hexafluoride MoF6 SF SF KZ 3 to Neon Ne Ar N V 10 to Nitric Oxide NO N C2H V 10 to Nitrogen N2 N N V 10 to Nitrogen Dloxide NO2 N2O N2O KZ 10 to Nitrogen Trifluoride NF3 C2H N2O KZ 10 to Nitrogen Trioxide N2O3 C2H N2O V 10 to Nltrosyl Chloride NOCI C2H N2O V 10 to Nitrous Oxide N2O N2O N2O V 10 to Oxygen O2 N N V 10 to Oxygen Difluoride OF2 C2H N2O KZ 10 to Ozone O3 N2O N2O V 10 to Pentaborane B5H9 SF N2O V 3 to n-pentane n-c5h12 SF N2O V 3 to Perchloryl Fluoride CIO3F C2H SF V 10 to Perfluoropropane C3F8 SF SF V 10 to Phosgene COCI2 C2H SF V 3 to Phosphine PH3 N2O C2H V 10 to Phosphorous Oxychloride POCI3 SF SF V 3 to Phosphorous Pentafluoride PF5 SF SF KZ 10 to p.46

49 _APPENDIX A Conversion Factor Rel. To Cal Cal Dynamic Heat Specific Specific Response Cpx10 3 Heat 25 C Code Gas Symbol Test GasTest Gas N2 Test Gas (J/k. mol) Phosphorous Tribromide Phosphorous Trichloride Temp ( c) Density Sug. Seal Cp (Cal/ C Mat. g C) Std Cal Press (Psid) Molecular Factor PBr3 SF SF V 3 to PCI3 SF SF V 3 to Propane C3H8 C2H N2O V 10 to Trichlorethane (TCA) C2H3CI3 SF SF V 10 to Trichlorethylene (TCE) C2HCI3 SF SF V 10 to Trichlorosilane SIHCI3 SF SF KZ 3 to Trisobutyl Aluminum (C4H9)3AI SF SF V 3 to Trimethylamine (CH3)3N SF N2O V 6 to Trimethylborate (TMB) B9(OCH3) 3 SF SF V 1 to Trimethylphospate (TMP) P(OCH3)3 SF SF V 1 to Tritlum* T2 N He to Tungsten Hexafluoride WF6 SF SF KZ 3 to Uranium Hexafluoride UF6 SF SF KZ 3 to Vinyl Bromide CH2CHBr C2H SF V 10 to Vinyl Chrolide CH2CHCI C2H N2O V 10 to Water Vapour H2O N N V 3 to Xenon Xe Ar SF V 10 TO Note: Conversion of controller to or from these gases may alter dynamic response or stability In accordance with SEMI Standard E12-86, Standard Pressure is defined as 760 mm Hg (14.7 psia), Standard Temperature is defined as 0 C. 1. Mathson Gas Book; Braker, William and Mossman, Allen L; Sixth Edition, JANAF Thermochemical Tables; Chase M.W., et, al,; Third Edition, Lange's handbook of Chemistry, Thirteenth Edition; Dean, John A, McGraw Hill, Touloukian, Y.S, et, al,; Viscosity, Nonmetallic Liquids and Gases, IFI/Plenum Data Corp., Handbook of Chemistry and Physics, 70th Edition, CRC Press, Suggested seal is KZ with a composite of INITIAL CAL USE C2H6 GAS (CONVERSION FACTOR=0.874). IF CF4 IS NOT AVAILABLE USE N 2 O. p.47

50 _APPENDIX B PROCEDURES TO AVOID CONTAMINATION APPENDIX B Gas systems for Silane and other highly reactive gases are extremely vulnerable to contamination. When Oxygen, water vapor or other gases combine with highly reactive molecules, solid contaminants, such as Silicon Dioxide, form in the system and can cause numerous problems with measurement and control equipment. These particles can be transported in sub-micron sizes that pass through filters, or can be formed by reactions in the plumbing downstream of the filter. Although proper use of filters reduces contamination, this potential problem exists throughout the entire system. The three primary causes of contamination are leaks, impure purge gases, and improper purging procedures. These problems and their solutions are discussed below. 1.0 LEAKS Plumbing leaks cannot be tolerated in a pure gas system. It is commonly believed that if a gas line pressure is above that of the ambient, the surrounding atmosphere will be prevented from entering the system. However, for any flow through an orifice or leak path, back diffusion from the surrounding gas (air) takes place into the gas stream. The system can then become contaminated with oxygen or moisture. THEREFORE, AVOID ALL LEAKS. Check the system when new, after replacing any equipment in the plumbing circuit, and on a periodic schedule. A leak detector capable of detecting leaks in the range of less than 1x10-10 atm cc/sec of Helium, is recommended. 2.0 IMPURE PURGING GASES Before and after a highly reactive gas system has been exposed to air, it is necessary to purge the system with an inert gas, i.e. N 2, or Ar with less than 10 ppm O 2, and water vapor. PURGING IS NOT NECESSARY, NOR IS IT RECOMMENDED, AT ANY OTHER TIME Each time a transition is made from purge gas to process gas or process gas to purge gas, there is mixing of the two gases throughout the plumbing; any oxygen or moisture in the purge gas reacts and can be left behind as contamination. The practice of purging process lines between runs gives two potential mixing events per run, and can cause a cumulative buildup or contamination. With leaktight plumbing it is not necessary to remove process gas from the system. Buildup resulting from repetitive purging can be avoided by not purging between runs. p.48

51 _APPENDIX B In some installations process gas is fed into a reaction chamber that can be exposed to air, thereby causing oxidation of residual gas in the gas supply line. As a preventative measure, installation of a shutoff valve in the process line, close to the reaction chamber, is recommended. 3.0 PROPER PURGE PROCEDURE The most effective method for removing process gases from process tubing is cycle purging. Cycle purging alternates evacuating the gas system and pressurizing the gas system with an inert purge gas. This procedure causes absorbed molecules and trapped gases to be removed much more quickly than straight purging. Contaminants trapped in plumbing dead space and microcavities can communicate with the process stream to cause virtual leaks. Cycle purging helps to purge these cavities. Although the application of vacuum to the gas system is very effective, a similar procedure can be adapted for atmospheric systems. 4.0 VACUUM SYSTEMS Figure 9 is a picture of a typical reactive gas flow controller installation. To initiate purge procedure, close valves 2 and 3, and open valve 1. Evacuate the line to base pressure. Close valve 1 and open valve 3 for one or two minutes to pressurize the controller with purge gas. Close valve 3 and open valve 1 to evacuate the controller back down to base pressure. Repeat the alternating application of evacuation and pressurization at least 20 times. When removing the flow controller, pressurize it with the purge gas and then close all 3 valves. 5.0 ATMOSPHERIC SYSTEMS Although a vacuum pump is highly desirable, a similar procedure can be performed without a pump. An aspirator powered by a high rate of purge gas flow to exhaust can be used to create a sub atmospheric pressure in the plumbing system. If an aspirator is not available, cycling between atmospheric pressure and purge gas line pressure is better than simply flowing purge gas. Pressurize and depressurize the controller for about 5 minutes, and repeat the procedure at least 40 times, rather than the 20 used for vacuum systems. Figure 9: Highly Reactive Gas System p.49

52 _WARRANTY Figure 10: Sample Decontamination Letter p.50

53 _WARRANTY Product warranty information can be found on our Celerity website at This information provides general warranty information, limitations, disclaimers and applicable warranty periods according to product group. CELERITY, INC. 915 Enterprise Boulevard Allen, TX USA Telephone Facsimile For technical assistance, contact Celerity Technical Support at Celerity is a trademark of Celerity, Inc. All other products or service names mentioned in this document may be trademarks of the companies with which they are associated. System descriptions are typical and subject to change without notice Celerity, Inc Rev /08 p.51