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MIT 6 003 - Vacuum Pump Down and Venting Procedure, CRaTER Thermal Vacuum System

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Rev.ECODescriptionCheckedApprovalDateVacuum Pump Down and Venting Procedure,CRaTER Thermal Vacuum SystemDwg. No. 32-06003.05Revision 021. IntroductionRev.ECO Description Checked Approval Date01 32- 226 Release M. Smith 8/21/0702 32-239 Update after review M. Smith 8/24/07Vacuum Pump Down and Venting Procedure,CRaTER Thermal Vacuum SystemDwg. No. 32-06003.05 Revision 02August 24, 200711. Introduction1.1. Activity Description The procedure defined here in defines the steps for pumping down and venting the Crater Thermal Vacuum chamber.1.2. Chamber Components The chamber and accessory electronics are situated on and around the chamber. The photos below identify the major components as they are described in this procedure.2Valve #1Figure 1. Chamber Valves and componentsValve #1- Large Chamber Vent ValveValve #2- Diffuser Vent ValveValve #3, Main Gate ValveValve #5- Secondary chamber vent Valve. Do Not Touch.Valve #6- Pump Volume Vent Valve, near turbo pump.TC1- High Pressure Gauge for Large Chamber Volume.PG1-Low Pressure Gauge for Large Chamber Volume3Valve #2Valve #5PG1TC 1Valve #3Valve #6Figure 2. Dewar ComponentsGas Nitrogen Valve- Green Valve to DewarPressure Regulator- Larger Black Knob to adjust pressure of N2. Turn clock wise to increase pressure, turn counter clockwise to decrease pressure.Regulator Shut off Valve #8- A secondary Valve to nitrogen line. Figure 3. Flow Gauge, for Vacuum Backfill4PressureRegulatorRegulatorshut offValve #8Gas NitrogenValveValve #9NitrogenFlow GaugeThis FlowGauge Is not usedFigure 4. Roughing Pump and ValveFigure 5. Pressure Gauge Displays5Valve #4RoughingPumpPM 31 (High Vacuum)Pressure GaugeDisplay/ ControllerTC Pressure Gauge (Low Vacuum)Display2. Procedures2.1. Pumping Down the Chamber2.1.1. Verify that both the chamber volume and pump volumes are vented. Ensure that all pumps are off.2.1.2. Ensure that the “Main Gate Valve” is open. Look through the chamber to see that it is open.2.1.3. After all electrical tests, pictures are taken, and verifications are completed, inspect gasket on door and wipe with clean dry Alpha 10 wipe. (Proper clean room attire must be worn. Clean gloves and wipes are required.). Close the front door and latch shut.2.1.4. Close “Large Chamber Vent Valve”, Valve #1.2.1.5. Close the “Pump Volume Valve”, Valve #6.2.1.6. Ensure Valve #5 is closed.2.1.7. Close “Diffuser Vent Valve”, Valve #2.2.1.8. Set Nitrogen Flow-1. Open the “Gas” Nitrogen Valve (Green Valve), on Nitrogen Dewar,all the way and open Regular Shut off Valve #8, on the pressure regulator, all the way.2. Open the “Nitrogen Flow Gauge Valve”, Valve #9, 1 full turn (close first then open 1 full turn). Open the “Flow Rate Check Valve”, Valve #7.3. Adjust pressure to 5-7 psi by turning the larger black knob on the pressure regulator. Turn Clockwise to increase pressure; turn Counter Clockwise to decreases pressure.4. Adjust the flow rate to 6-8 SCFH by turning the small black knob onthe “Nitrogen Flow Gauge Valve”, Valve #9.5. After all adjustments are made close the “Flow Rate Check Valve”, Valve #7.2.1.9. Plug in the roughing pump in an outlet separate from the outlet that the electronics are plugged into so as not to overload the circuit. Note the date and time started in log book. 2.1.10. After the TC Vacuum Gage reads below 100 millitorr turn on Turbo pump. (The turbo pump power button is at the rear of the controller and the start button is in front of the controller). Note time Turbo pump was started in log book.2.1.11. After 8 hours plug in the power to the High Vacuum Pressure Gauge Controller, PM31. Install the cable to the gauge. Turn on the controller by pressing the HV button. Document pressure at periodic intervals in log bookor use the pressure monitoring software on the computer, approximately hourly if done manually or every 5 minutes if done using the computer, during normal operation. 62.2. Venting the Main Chamber Volume.Note. The Chamber is to be vented in two separate volumes. The first volume to be vented is the Main Chamber. The second volume to be vented is the Pumping Chamber. These two volumes are seperated by the MAIN GATE VALVE, Valve #4.1. Shut off the Penning Vac PM31 pressure gauge at the controller by pressing the “HV” button. The controller should then read “Off”. Remove cable from gauge by loosening the retaining ring, then pull off. Unplug the power cord.2. Ensure there is enough nitrogen in the tank to vent. (1/4 tank min). 3. Ensure Nitrogen is flowing by opening the “Flow Rate Check Valve”, Valve #7. Watch the flow gauge ball and ensure it is at 6-8 SCFH. Once flow is set then shut “Flow Rate Check Valve”, Valve #7.4. Close the “Main Gate Valve”, Valve #3.5. Open the “Diffuser Vent Valve”, Valve #2, two full turns.6. Open the “Large Chamber Vent Valve”, Valve #1, two full turns.7. After a few seconds, open the “Large Chamber Vent Valve”, Valve #1, all the way. 8. After a couple of minutes open “Diffuser Vent Valve”, Valve #2 all the way. 9. Increase flow in “Nitrogen Flow gauge”, Valve #9 to 9-10 SCFH. The chamber will take 2-3 hours to vent. Release the two door latches. The front door will pop open when venting is complete. 72.3. Venting the Pumping Chamber Volume.Note. The Chamber is to be vented in two separate volumes. The first to be vented is the Main Chamber Volume. The second to be vented is the Pumping Chamber Volume These two volumes are seperated by the MAIN GATE VALVE, Valve #3. Before pumping the chamber down the Pumping Chamber Volume must also be vented.1. The Penning Vac PM31 pressure gauge controller should read “Off”. If a pressure is being displayed then press the “HV” button on the controller. 2. The “Main Gate Valve”, Valve #3, is closed. Do not touch it. Do not try to verify that it is closed. If you open it even slightly it will damage the pumps!3. Ensure that there is enough nitrogen in the tank to vent. (1/4 tank min). 4. Ensure Nitrogen is flowing by opening the “Flow Rate Check Valve”, Valve#7 on the nitrogen line. Watch the flow gauge ball and ensure it is at 6-8 SCFH. Once flow is set then shut “Flow Rate Check Valve”, Valve #7.5. Shut off the Turbo pump by pressing the “Stop” button on the Turbo pump controller. 6. After 10-15 minutes, close the “Roughing Pump Valve”, Valve #4. 7. Open the


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