Mark D., Tyler G. and Bubba G. having tacked on both of HAM3's doors this afternoon has left us with only three chamber door openings with soft-covers on.  As such, we had to dial back the purge air supply from its recent nominal value of 100% open to something much less so as to not blow these three covers off!  Again, not yet having a flow meter in-line with the purge-air supply results in many theories etc.. but everything now seems typical of the historical behavior with the purge air.  Also, the dew point is dropping as a result - two hours after HAM3's doors went on it has dropped down to -31C from a months long steady value of around -28C.  

BSC1's annulus pressure is still good and getting better (see discussion from yesterday).  BSC3's annulus pressure, on the other hand, had seemed to have bottomed out at the pump cart (2.1 x 10-5 Torr) since yesterday.  So, this evening, I closed the annulus isolation valve and noted that the pump cart pressure didn't respond.  Having a leak on the pump side of the isolation valve "muddies the water" a little bit.  We don't have the luxury of starting the ion pump and monitoring the current over a period of days - so, we will try and spray a little helium tomorrow so as to rule out an outer O-ring leak that might be getting "masked" my the pump-side leak.  

The fourth of 4 NEG pumps is finishing up a "cycle" of particulate mitigation in the lab and should make the deadline tomorrow to be available to get installed.