PKR 251 Pressure Gauge

Files

10/27/2017

Nick and I determined that both sides of the polar inset should be the same color. When I had opened up the gauge, one side had a black coating (it kinda looked like graphite. It probably wasn't, but that's what it looked like). It was extremely hard to get off. I had to use coarser sand paper than the instructions recommended, but that does not seem to of had any adverse effects. FYI, it took a while, even with the coarse sand paper.

10/20/2014

The pressure gauge is reading a constant 4e-3 mbar whether the cryostat is at room temperature or cooled down with liquid helium. This is too high of a pressure. Because we have not changed the anything with the cryostat that would have caused a leak in the vacuum and because the reading is not changing at all, I think the pressure gauge is not reading the correct thing rather than there being something wrong with something else in the system.

I contacted Pfeiffer Vacuum and they sent the manual and cleaning instructions above. I took the gauge apart and cleaned it as instructed, but I did not replace any parts. It seems to be working fine now.

8/5/2015

The pressure gauge was reading a constant 4e-3 mbar like described above on 10/20/2014. I cleaned it out again. I'm not sure how those gauges work really, but maybe if we have the cryostat at atmosphere for long periods of time (days/weeks?) we should shut the pressure gauge off? That might prevent this build up from sputtering all over. Last time, someone at Pfeiffer Vacuum suggested that having the pressure gauge on an elbow might reduce the amount of cleaning needed.

After cleaning it out the pressure isn't reading below 3e-1 mbar, but the turbo pump is turning on so the pressure gauge must just not be reading correctly.

8/12/2015

Yesterday the turbopump shut off after warming the cryostat up after trying the experiment, so it turns out there was a leak. I took the gauge apart and cleaned everything again and changed all the o-rings. It seems to be working now.