J. Oberling, R. Savage, P. King, J. Bartlett

The goal for today was to replace the flow sensors for both PSL chillers with new ones with no moving parts; we have to bring both chillers down to replace one, so might as well replace both.  Once we swapped out the flow sensors both PSL chillers quit working, giving the same error; we are in touch with the service dept to figure out what happened.  In order to get the PSL back up and running we installed the spare PSL chillers, which we had also installed new flow sensors in.  As it turns out, these new flow sensors don't play nicely with the chillers for some reason not known to us.  We therefore re-swapped the old flow sensors that were originally in the spare chillers.  As our luck would have it, the diode chiller flow sensor was reporting no flow when we could clearly see flow; we replaced this flow sensor with one from the original chillers.  By this time we had lost track of which flow sensor was from the crystal chiller and which was from the diode chiller (the one we originally suspected as beginning to fail, thereby causing the PSL trips we have been seeing).  In other words, we traveled in one huge circle today, and the original problem with the PSL diode chiller flow interlock tripping may not be fixed.  Luckily, we are all now experienced in swapping these flow sensors out, so if the PSL does happen to trip again because of the diode chiller flow interlock, we will swap it again.

As it happens, the PSL tripped as I was writing this alog.  Jeff and Peter had already made it out, so Rick and I swapped the flow sensor and got everything to work after some issues.  More detail on that to come tomorrow, as now I'm tired and hungry.