HP HTR 8 level transmitter showing very low reading. Check at local gauge glass found actual level low. Check at the emergency control valve found, High Pressure Heater No.7 and No.8 valve position not fully shut and causing the HP HTR level drain to the flash box. DCS command to the control valve already fully shut. Suspect not enough air pressure to close the control valve (air to close).After doing some checking, not enough air pressure to close the control valve from the volume booster. The function of volume booster is to boost big volume air to the valve diaphragm either fast closing or fast opening. Servicing done for all volume booster HP Heater and reading back to normal operation.
Checking at the store found that the stock level for this volume booster is also low and need to raise new purchase request. I enclose here the photo and the specification for you to review.
Volume Booster
Blackborough Control Valve Model No : 25
SWP : 150 Psig
Pipe Conns : ¼ ” NPT
