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2nd Follow up Special Gas Coordination Panel (press. Reg.)
Description
Present:
Christoph Schaefer, Tom Meyer, Ray Gregory, Allain Gonidec, Serguei Konovalov, Anatoli Romaniouk , Ferdi Hahn
Short Recap of the Conclusions:
Serguei showed that all tested regulators (from Zimmerli and Backofen) give some ageing. The cleaning of all metal parts (done at CERN) cannot prevent the ageing (see sample 2057).
Looking at the individual parts of the regulators, Serguei could identify the Viton membrane to cause ageing, other elements (PTFE parts, Viton seat, etc.) tested do not cause ageing.
Although this was unexpected, it seems that the Viton membrane generates the ageing problem. Serguei will make further tests on this subject.
It is generally believed that the Viton membrane itself is not really a critical item for the other (other than TRT and OT) detectors. And, the membrane is exchangable, even later, if there would be problems revealed in the future.
Mechanically it is expected that Viton would be more durable and more resitive than PTFE (especially for the larger pressure settings), and it will therefore require less maintenance.
It is agreed that we order the pressure regulators from Zimmerli.
Conditions to be clarified with the supplier:
The PTFE and Viton parts of the regulators should be cleaned by Zimmerli with alcohol. All metal parts of the regulators have to be cleaned with a procedure similar to the one we use at CERN. Every batch cleaned should have a control probe (a metal plate provided by us) in the bath, which is returned to us with the pressure regulators.
If possible the cleaning should be done by the subcontractor of Zimmerli, the procedure and the extra cost need to be discussed.
The assembly shall be done in clean conditions with the technician wearing gloves.
Membranes:
The following systems shall have PTFE membranes:
ATLAS: TRT, TGC and CSC.
LHCb: OT.
All other systems will use Viton membranes.