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| Step # | Description | Notes / Reasons |
|---|---|---|
| 1 | LN2 in nitrogen reservoir must be completely boiled off. | Running a large gHe flow through the purifier will speed up the boil off but the LN2 tank heater is the best way to speed up this process. You can leave the heater on even after there is not liquid nitrogen in the purifier but you must close BV02 before the purifier goes below 15%. The LN2 level will start decreasing slowly, and the "TA_Top" and "TA_Bot" temperatures increasing slowly. If all the way full it usually takes about 24 hours to boil everything off and see the temperatures to go above ~274K. So start this process before you need to regenerate. Monitor T1A and T2A parameters on the strip charts. |
| 2 | Close BV02 manually
| This valve isolates the cold heads from the purifier. You must close this valve to ensure no contamination reaches the liquefier and cause unnecessary downtime. Make sure this is closed before any expected contamination is released. |
| 3 | Switch both the liquefiers to "Run + Auto + Idle". | |
| 4 | Check Valve Settings on QuantumPure He Overview and ensure the solenoid valves V9a and V21a are open. | |
| 5 | Close V30 hand valve on HR3. | This is to isolate the outside gHe tank from the purifier. Note: At this time the purifier helium space's pressure would be same as the tank pressure |
| 6 | Open SV01 on QT-HMI main manifold | This is to open the path from the outlet of the purifier to the Vvent |
| 7 | Crack open Vvent while someone watching P40 pressure gauge on HR3 front panel. | This is to bring down the pressure inside the purifier as a preparation to open V10a. |
| 8 | Open V10a on QT-HMI screen (Navigate to Purifier Overview → He Overview) | This may make some noise because a sudden relieving of the pressure in the purifier helium space via V10a, but as long as there is not significant pressure there its fine.. |
| 9 | Close Vvent hand valve | |
| 10 | Check the position of V35. You can leave it open so that you can clean all the way to BV02, but be sure BV02 is nice and closed as its the only thing separating the cold heads from the contamination on the otherside. | If you want to close it for now that is also fine, but when you pump and purge you should open it up to clean out this path. When closed it provides insurance that the purifier helium space is isolated from the rest of the system when opened to the atmosphere via V10a |
| 11 | Make note of the Helium Pressure P10 and check the pressure in P40 and P41. They should be near zero now. | You can perform this procedure at any pressure in P10 but you will have to reduce this same pressure in the purifier and bring the purifier back up to this pressure when procedure is over. |
| 12 | Ensure VNVA is open, and Turn ON the purifier heaters if not already on, by clicking both "Heater MC Cycle" and "Heater MC Stop at SP".
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| 13 | Connect the pump/purge setup (small manifold with pump, gHe cylinder, pressure gauge, and hand valves) to the V10a outlet port. You should have two valves, one to isolate the pump during the purge process and one to isolate the gHe cylinder during the pumping down. Always leak check when you assemble this manifold by pressurizing once its all connected and putting on snoop to search for bubbles. You can start pumping even when there is LN2 still in the purifier. The grey Edwards pump is the best for this procedure as it can go close to full vacuum. |
You need not wait until TA_Top and TA_Bot temperatures reach ~274K. |
| 14 | Start the pump and open the hand valve connected to the pump. | The heater on purifier LN2 should stay ON the whole time. |
| 15 | Wait until the pressure on the gauge reaches the lowest (usually it takes about 15-20 mins) which is around -30 In Hg. | |
| 16 | Close the black-hand-valve to the pump. | |
| 17 | Regulate the pressure of the gHe bottle ~3 psi and then open the valve to purge the purifier gHe space. | |
| 18 | Close the valve when the pressure gauge reads ~3 psi. | |
| 19 | Open the valve to start pumping down. | |
| 20 | Repeat the pump and purge process for no less than 10 times. Leave it pumping over night with the heaters ON | 3 days of pumping down (or more) would be recommended for a thorough cleaning but when time is tight 1 night will due. |
| 21 | After being done with the last cycle of pumping, Close the valve to the pump. | |
| 22 | Regulate the pressure of the gHe bottle ~3 psi and then open the blue-hand-valve to purge the purifier gHe space. | |
| 23 | Close v10a on QT-HMI screen | |
| 24 | Open V30 hand-valve slowly until it is fully opened | |
| 25 | Open v35 hand-valve slowly until it is fully opened | Once you open V35, the line up to BV02 and Vvent will be pressurized. |
| 26 | Check the pressures on p41 and p40 on the HR3 front. Both should read the same value. Its a gradual equalization. If it does not read the same value (within a couple PSI), then go back to the pumping and purging process for no less than 10 more cycles. | |
| 27 | Detach the pump/purge manifold if you are not going to perform purifier regeneration again soon. | |
| 28 | Ensure SV01 is open | This is to bleed gHe to ensure the atmosphere is not trapped in the piping section up to BV02 |
| 29 | Crack open Vvent and flush/bleed gHe through Vvent for a few seconds | You can open and close that Vvent valve to pressure purge. Pulsed pressure is the best way to move contaminants out. |
| 30 | Close Vvent hand valve | |
| 31 | Following the procedure, fill the purifier using the warm purifier up to 90% filling procedure | Note: During this process, purifier can go to the Alarm mode. If it does so, reduce the pressure in the purifier and clear the Alarm on "Purifier Alarm Page" and open V9a and V21a valves (these valves will be closed when purifier goes to the Alarm mode). The warm fill process is the same as the normal fill process except you must keep EV-200 open during the entire fill and regulate in inlet LN2 flow at the LN2 tank outside by closing down HCV-13. The recommended opening is about 3/16 of a turn where for the normal fill this valve can be 1 turn full.
Note: That the color code of VNPA is reverse. Red means open and green means closed. This is the purifier LN2 space in hall relief which connects to the copper hose. |
| 32 | Once the purifier is filled with LN2 up to 90% level, then ensure V9a and V21a are opened | |
| 33 | Perform the steps 26 and 27 again to clean the line with purified gHe | |
| 34 | Close SV01 | |
| 35 | Open SVSAMPLE followed by the green pressure regulator and the flow-meter to have a flow to the purity meter and ensure you can read 100% or slightly above. This purity meter is not particularly accurate so you should also check with the Hand held unit.
| Also use the portable purity meter setup to confirm the purity with PM01.   |
| 36 | Close SVSAMPLE | You can leave the green-hand valve and flow-meter opened so you can remotely open SVSAMPLE at anytime to measure the purity of the purified helium from the purifier if need. You can also close it if measurements not needed. |
| 37 | Do one final walkthrough to ensure all valves and opening to the the purifier are close and you are ready to connect the liquefier back to the purifier then open BV02 hand-valve slowly until it is fully opened. You are able to start up the liquefier again as needed.
Once you have started the liquefier again and flowing at normal production P40 and P41 should be pretty close assuming the system is at higher pressure as seen here. At lower pressure you may still see a bit of a difference but not over 10 psi in most cases. | Now purifier regeneration is complete. As soon as the purifier is above 30% full you can start with the other steps to move things along. Do not step the purity check before opening BV02 and starting liquefaction again. |
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