aLIGO LHO Logbook

H1 PSL (PSL)

corey.gray@LIGO.ORG - posted 06:53, Monday 20 February 2017 - last comment - 17:46, Wednesday 22 February 2017(34261)

14:43 Lockloss Due to Another PSL Head 1-4 Flow Error

After 12min of OBSERVING, had another PSL trip.

Went to the PSL Chillers and there must have been an explosion of water in there. The Crystal Chiller cap did NOT pop off. The Crystal & Diode chillers both have Error Alarms (Crystal has Flow Sensor Alarm & Diode has F2-Error).

Will probably call Jason shortly.

In CORRECTIVE MAINTENANCE state.

Comments related to this report

jason.oberling@LIGO.ORG - 09:39, Wednesday 22 February 2017 (34317)

Link

As with the first trip documented here, this one also appears to be caused by an erratic flow reading in the Laser Head 2 flow sensor. As before, the flow reading from the head 2 sensor becomes erratic before the trip and begins to drop, eventually hitting the trip point and tripping the interlock. The first attachment shows the 3 flow rates from the Laser Head circuit (once again, the 4th flow sensor is forced to a specific value in Beckhoff so cannot contribute to the trip). The 2nd attachment is a zoomed in view of the Laser Head 2 flow sensor signal.

As for the F2 error on the diode chiller, this error did not cause the chiller to turn off. I remotely turned it off and asked Corey to power cycle the chiller. This cleared the error.

Images attached to this comment

jeffrey.bartlett@LIGO.ORG - 17:46, Wednesday 22 February 2017 (34333)

Link

  The plug not popping off can be a problem. When the pump stops there is a back surge of water into the reservoir, which is what blows off the plug and sends a shower of water onto the floor. If the plug is too tight to allow the pressure from the back surge to relieve, there is a chance of cracking the reservoir. 

   I will call Technotrans to see if there is a better way to relieve this back pressure. Until I hear from them PLEASE DO NOT reef down tight on the plug. Leave it lose. Cleaning up a bit of water on the floor is a lot better than swapping out a damaged chiller.