Corey alerted us to a low TCSY chiller flow - as alarmed on the side ops station.  Jason inspected at the chiller and found the usual nominal ~4 GPM, all good there.  A trend shows the flow sensor (which causes the alam and is out on the floor on a pipe under ~BSC2) has dropped, similar to what it has been doing (alog 31900). However this time seems to be taking longer to recover.  The value dropped from ~3.1 to 2.6 and is now bouncing around more than it had at the 3.1 value.  In the last 50 minutes it seems to be on a slight rise, but not out of the woods.  We spoke with Alastair just now to find out how low this can go before something else happens such as triggering the laser off.  He is going to look up to see if there is any hard coded trip set points somewhere.  However, in the 90 day trend attached Jason and I note (puprle ellipses) that there have been quite a few times that this flow sensor has dipped briefly below 2 and even 1 and the laser has been uneffected.  SO, we're hoping the flow sensor rides out long enough for us to schedule a Tues maint period to swap in the spare flow sensor. 

Ops - if the TCSY laser does anything funny this weekend AND the flow drops well below 3 and is staying there, call us.