I tested the cryopump interlock today. It is touchy. I do not have full confidence in it.
I'm proposing that VC1 gate valve should be kept closed while nobody is working in the 40m lab.
How to open gate valve:
1, confirm temp of 12K on the gauge at the bottom of the cryopump
2, if medm screen cryo reads OFF( meaning warm) hit reset will result reading ON (meaning cold 12K )
3, open VC1 gate valve if P1 is not higher than 20 mTorr
VC1 was closed at 18:25,
IFO condition: not pumped,
expected leak plus out gassing should be less than 5 mTorr/day
The RGA is in bg-mode, annuloses are closed off
The Cryo pump is running reliably since April 22 hence there is no need to close VC1 repeatedly.
The photo switch interlock was put back onto the H2 vapor pressure gauge and it is working.