Problem mrc SNF 2012-07-31 17:05:23: Foreline pressure burst during roughing

[jimkruger at snf.stanford.edu]

Everytime I pump down the chamber, a rapid pressure rise in trhe forline occurs.  This is not my failure to wait long enough with the pump-down switch, it happens at the "halfway pumped" pressure.  I speculate that it is the "unloading" of the gate valve opening a leak.  Perhaps a new O-ring on the gate valve?