Yesterday, starting work on the HEPI Corner Station Filter change, WP 7169, we observed an interesting behavior of the BSC2 Pressure sensors on the supply lines to the LVEA HEPIs at BSC2.  When the large ball valves up on the mezzanine were changed to put the system local to the Pump Stations into recirculation mode, the BSC2 pressures started climbing.  At the same time, the pump stations were started to recirc the fluid rapidily to get turbulent flow in an effort to clean out the reservoir.  This confused us as the BSC2 sensors are valved out so should have no knowledge of what the pump stations are doing.

Ultimately we decided it must have something to do with the head the plumbing has wrt the BSC2 pressure sensors but those numbers don't really yet make sense.  Meanwhile, the pump stations were shut down over night, and as you'll see on the attached trends, you'll see that the pressures at BSC2 began falling back to zero but not until hours after the PSs were back to zero.  Very interesting/confusing.

I'll restart the recirc op this morning and we'll see what happens.  Could the $xxx 1-1/2" swloc ball valves be leaking...