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1. QT System Starting Procedure
2. Liquefier Cleaning when Dewar contains LHe
3. Cleaning QT purifier Helium-space

Useful information

1. The volume of an outside gHe tank: 1600 cubic feet
2. QT recommendation to keep system minimally pressurized: ~20 psi
3. Running from 40 psi down to 20 psi would produce about 80 liquid litters and we should be able to do that in about 10 hours
4. HR3.docx

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1. Helium Compressor Manual.pdf
2. Cold_Head_Hot_Swap_Procedure.pdf
3. prosense_qps.pdf

Maintenance Procedures

1.  Cleaning QT purifier Helium-space from the top of the purifier Dewar (This needs to be done periodically because the purifier will be blocked by the contaminants from regular air)
   a) Change the operation to "Manual" + "Run" mode, and close the SV01 and SV03 valves: also close the BV02 hand valve and REGX regulator on the liquefier manifold
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   b) Make sure to boil off and vent all the LN2 before the pumping-purging procedure. Use the heater if necessary (tap on the small bar located bottom of the purifier sign: orange color indicates that heater is ON).
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   c) Connect the pump to the outlet from V10a (currently we use the Edwards pump which is connected to the Helium recovery manifold pipe) with a pressure gauge, hand valve, and a Helium gas bottle (to backfill).
        Keep the V9a closed during pumping and purging.
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     Cleaning QT purifier Helium-space including the HR3 compressor lines up to the manifold
   

   1) Open V9a and V21a from PLC
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   2) keep V30 hand valve closed
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   3) Keep BV02 & RegX hand valves (going to/from liq A, B) closed
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   4) Open SV01 and SV03 (Note: if the valves are not opening via PLC, then check whether the system is in Manual + Run mode, if not select that mode to open SV01 and SV03)
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   5) Pump down using the setup that we just installed on the Vent.
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   6) Opening hand valve V30 slowly increases the pump sound (takes a couple of seconds to respond due to the long path to reach the pump)
        See the above picture in step 2