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Mon Dec 8 11:41:27 2008
The rough pump for the TP2 replaced
The foreline pressure of the TP2 (the foreline pump for the main mag-lev turbo (TP1)) was at 2.8torr this morning
when Bob came in.
Looked like the foreline pump (Varian SH-110) was leaking.
Bob started the backup rough pump in parallel with the "leaking" one to keep the foreline pressure low.
We then closed the valve 4 (between TP2 and TP1) and stopped the TP2 and the SH-110.
We replaced SH-110 with another one, but still the foreline pressure was high.
So we replaced it with yet another one. We also changed the quick coupling fasteners on the SH-110 and wiped the O-rings.
This time, it worked fine and the foreline pressure dropped to around 38 mTorr.
Since there is no valve between the TP2 and the SH-110, we could not keep the TP2 running while we were replacing the
problematic SH-110. This means the TP1 was running without a foreline pump during the work. We tried to minimize the
down time of the TP2. The temperature of the TP1 was 33.6C before we stopped the TP2 and it went up to 37.3C during the
work. It is now coming down to the original temperature.
Since we don't know if the problem was caused by bad SH-110s or leaking quick couplings, Bob is checking these apparently