chandra.romel@LIGO.ORG - posted 11:02, Friday 12 January 2018 - last comment - 16:37, Friday 12 January 2018(40118)
EY purge air alarm
Measured dew point of EY purge air for about 12 minutes this morning, with no demand (closed off metal valve to get flow through pressure relief valve). DP crept down to -25.3degC. Then found a "switching failure alarm" on at the control panel (visual only - no sound). I reset and re-measured DP. Quickly dropped to -22degC in several seconds. The two drying towers appear to be cycling between regenerating and drying.
Compressors are running between three and four units with current flow. Output pressure is 0.5-0.7 psi. Soft cover was on BSC door, but arm is in chamber.
Other vacuum site checks OK - three turbo stations in corner, corner purge air, CP4 IP. Leak checker at OMC turbo is currently running to test He background.
Checked on EY purge air again this evening. All looks good. Dryers are cycling and DP measured -25.5degC (measured through a few cycles).