ECO Description 01 32 226 Release M Smith 8 21 07 02 32 239 Update after review M Smith 8 24 07 Rev Checked Approval Date Vacuum Pump Down and Venting Procedure CRaTER Thermal Vacuum System Dwg No 32 06003 05 Revision 02 August 24 2007 1 1 Introduction 1 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 Valve 1 2 Valve 2 Valve 5 PG1 TC 1 Valve 6 Valve 3 Figure 1 Chamber Valves and components Valve 1 Large Chamber Vent Valve Valve 2 Diffuser Vent Valve Valve 3 Main Gate Valve Valve 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 Volume 3 Gas Nitrogen Valve Regulator shut off Valve 8 Pressure Regulator Figure 2 Dewar Components Gas Nitrogen Valve Green Valve to Dewar Pressure 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 This Flow Gauge Is not used Valve 9 Nitrogen Flow Gauge Figure 3 Flow Gauge for Vacuum Backfill 4 Valve 4 Roughing Pump Figure 4 Roughing Pump and Valve PM 31 High Vacuum Pressure Gauge Display Controller TC Pressure Gauge Low Vacuum Display Figure 5 Pressure Gauge Displays 5 2 Procedures 2 1 Pumping Down the Chamber 2 1 1 2 1 2 2 1 3 2 1 4 2 1 5 2 1 6 2 1 7 2 1 8 Verify that both the chamber volume and pump volumes are vented Ensure that all pumps are off Ensure that the Main Gate Valve is open Look through the chamber to see that it is open 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 Close Large Chamber Vent Valve Valve 1 Close the Pump Volume Valve Valve 6 Ensure Valve 5 is closed Close Diffuser Vent Valve Valve 2 Set Nitrogen Flow1 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 on the 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 book or 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 6 2 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 7 2 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 Diffuser Valve Valve 2 two full turns 8 Open Pump Volume Vent Valve Valve 6 1 4 of a turn 9 After a 30 seconds minimum open the Pump Volume Vent Valve Valve 6 1 full turn 10 After 60 more seconds open the Pump Volume Vent Valve Valve 6 all the way 11 The Pumping Volume will eventually pressurize to 5 …
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