Cryopump Recharge
AKA: Post-Maintenance Helium Charging
Preparation Steps
Line Preparation:
Remove helium compressor supply lines, both supply and return, and cap both to protect the threads.
Remove the maintenance manifold from the compressor's supply line and attach it to the cryo's supply.
Remove the cap on the input of the Brass manifold (note: the brass manifold is bidirectional).
Helium Tank Setup:
Take the sprayer off our helium tank line.
Open the outermost valve on the Ultra-High Purity (99.999%) Helium bottle, followed by the regulator, and finally the bottle's main valve. This sequence prevents back-flow and potential contamination.
Turn on the helium flow lightly and start threading the UHP helium tank supply line onto the pump brass manifold.
Increase the helium flow so that the gauge reads 200 psi (note: the compressor will increase this from 200 to 280-300 psi).
Tighten fully to eliminate any hissing sounds.
Remove the brass manifold output cap and open the input valve.
Recharge Steps
Increasing Helium Pressure:
Increase helium supply pressure to 250 psi (adjust for regulator inaccuracies), wait until the maintenance manifold reads 250 psi, then close the inlet valve.
Pressure Reduction:
Reduce the pressure in the cold head to approximately 50-75 psi using the outlet valve of the maintenance manifold. Ensure not to reduce the pressure below 30 PSIG to avoid introducing contamination.
Pressurization Cycle:
Re-pressurize the cold head with UHP helium to 250 psi using the inlet valve, then close it. Repeat this step and the previous step four more times, totaling five pump/purge cycles.
Motor Operation:
Run the cold head drive motor for 30 seconds by plugging in the power. Repeat the last four steps four more times, leading to 5 sets of 5 full cycles. There will be an initial fill, 25 flushes, 25 fills, and 5 drive motor runs.
Top off to 250 psi if necessary.
Reattaching Helium Compressor Lines
Line Reattachment:
Remove caps from helium compressor lines. Check cryo fittings for the outer black O-ring (flat rubber gaskets) before reconnecting the self-sealing couplings.
Connect the return line first, then the supply. Run threads backwards on the helium line to ensure proper seating on the cryo fitting.
Tighten manually for 3-4 rotations. If resistance is felt, check for cross-threading. Use wrenches to finalize tightening without excessive force.
The compressor will increase the pump psi from 250 to 280-300 psi. Top off from the tank if the compressor does not reach 280 psi.
Finalization Steps
System Shutdown:
Run the drive motor for 30 seconds and verify that the cold head is charged to 280-300 psi.
Close the outermost valve on the UHP helium bottle's regulator, close the regulator, and then close the bottle's main valve to prevent back-flow.
Remove the line from the UHP helium bottle and cap the inlet and outlet ports on the maintenance manifold with blanks.
Plug in the drive motor and close the all-metal valve to the roughing manifold.
--OR-- (or some combination of the two)
Cooldown and Valve Management
Plugin the Pump for Cooldown:
Activate the pump to initiate the cooldown process.
Valve and Manifold Adjustments:
Close the gate valve on the all-metal valve to secure the system.
Cap the brass manifold output to prevent any contamination or leaks.
Turn off the helium tank to stop the flow.
Remove the helium line from the setup.
Cap the brass manifold input to fully seal the system.
Turn off the helium line to ensure no residual gas escapes.
Reassembly and Labeling
Reattach Accessories and Organize Tools:
Replace the helium sprayer on the tank line to prepare it for the next use.
Place the cryopump toolkit back in the cryo repair bin, ensuring all tools are accounted for and organized.
Labeling the Cryopump:
Once the cryopump has cooled down to the desired temperature, attach a new regeneration label. This label should include the date of the maintenance and any other pertinent information to track the maintenance history and ensure proper future use.