On October 31, Jim & I got all the WBSC9 (ETMX) HEPI Actuators connected.  This included a couple swaps of the Parker Valve on V3.  The process would have you shut the supply to the system to depressure the valve to minimize fluid loss/spillage.  Today while at EndX troubleshooting ISI electronics, the HEPI pump station was checked as it hadn't been for several weeks and fluid was found in the pressure relief drain hose suggesting the pressure had exceeded the ~125psi relief point on the mechanical relief valve.

The trends were checked and sure enough the pressure spiked on the 31st showing a max of 105psi.  Who knows how much higher it actually went relative to these epics data.  Regardless, I suspect this spike in pressure opened the relief valve briefly and then closed when it dropped.  The pump station pressure was controlled by servo and the controller reduced the motor speed accordingly.

Couple things  1) At the end stations there is only one chamber on the system so when the supply valve is shut, the system is dead headed.  Unlike the corner station which has isolating supply & return valves on every chamber, the end station will likely see this spike if the servo is on and the supply valve is closed too quickly.  Not sure if you can close the valve slowly enough to prevent this spike.  I suspect you might be able to do so having the motor slow to a crawl and keep the dead head pressure at the set point and not spike it too badly.  At the end stations, the better solution might be to reduce the set point to very low value and then slowly close the valve.  A good alternative may be to put the system into primary recirc mode; that is open the system by-pass at the reservoir.  Then the chamber valve could be shut with only minor concern about valve actuation speed and pressure spikes.

2) Now that the pressure relief drain hose has fluid in it, it should be drained to ensure it doesn't thicken/dry out in the line blocking future fluid flow.  Not sure if this is a probability but it certainly is possible.  Our experience with the fluid is that it does become more viscous once isolated in small quantities, i.e., drops or puddles.  Also, this fluid is no longer in the system and the reservoir is therefore closer to tripping for low level--something we'd like to avoid.

So, although long on my to-do list, alarms on the pressure channels should be installed with low priority guidance to investigate the pressure relief line and drain as needed.  At the same time, the fluid levels should be checked with respect to the level trip point and topped up as required.