Jeff B. informed us this morning that he had to add 400mL of water to the PSL crystal chiller, while last night it was fine.  Doing a humdity trend of the HPO box showed a sharp spike, indicating a possible water leak.  We immediately shut down the laser and chillers and went out to investigate.  Upon opening the HPO box we saw water covering the floor of the box and dripping out of the connection from the head 1 ASE dump to the head 1 flow meter (Hose_as_found_20160420.jpg); the hose had failed, causing a major water leak (in the picture you can see where the red covering ripped away due to the water pressure).  We mopped up all the water we could, drained the laser head water circuit, and removed the failed hose connection (Hose_failure_closeup_20160420.jpg).  Luckily the hose was long enough that all we had to do was cut off the failed portion and reattach the hose.  I took the failed section and removed the red outer covering and found a small hole in the silicon in what looks to be the area where the hose seals on the fitting (Hose_failure_point_20160420.jpg).  I think that the repeated loosening and tightening of this connection we have had to do over the last week, probably combined with the age of the hose, weakened the hose at this point causing its eventual failure.

We performed a preliminary inspection of the optics and it appears we may have lucked out; no water is visible on the surface of any of the optics in the HPO box.  We are currently letting the HEPA fans and the AC run for a copule hours to dry the HPO box out completely, and will then do a more thorough inspection of the optic surfaces of the HPO.