notes Videoconference, 13.April 2004

F.Haug, update on Cryosystem

FH presented a updated cost estimate (including an approximate separation of CERN/US contribution). Further slides presented here are can be viewed in the minutes of the local CERN meeting of 2nd April 2004 (minutes).

Further notes:

- All valves indicated in the flow-scheme are contained in the distributed-valve box (DVB).
- Drain valve is only used during commissioning and not needed for final operation. Could also be a safety item in case of firing a cold, wet (=LN2 filled) solenoid.
- possible drain of remaining LN2 in the solenoid can be released using an additional Helium supply, which forces the LN2 to exit via the drain valve to the cold vent.
- the current flow-scheme does not foresee any other LN2 reservoir than the main dewar, the DVB and the solenoid itself.
- a total of three LN2 lines are connecting the surface with the solenoid/DVB: cold supply, cold and warm vent
- cold vent is used to recool (keeping cool) the cold supply line during standby and of course during cooling the solenoid.
- solenoid is only fired in dry status (almost dry?), in order to minimize activation of LN2; mechanically it can be fired in wet status, as it is designed to operate He cooled and for an operating pressure up to 15 bar. Q: What is the maximum pressure in case of firing the wet solenoid?
- is a by-pass of the pump needed, to allow emergency release of LN2 in case of firing the wet solenoid. A realease path could also be via the drain valve and cold line (see above) or via the warm line, if heater is pre-attached. This is an issue to the safety review.