Pressure measurement
Pressure measurement
(OP)
Hello everybody,
I have got some doubts about the pressure measurement in a water plant.
There are two pressure transmitters, one upstream a centrifugal pump (head = 20 m) and another one downstream the pump.
The measured pressure downstream the pump is lower than that measured upstream. The pressure transmitters measure absolute pressure and not relative pressure and so, the measurement depends on the quote of installation.
How can I compare the two measurement? Which is the height that I have to consider as reference?
I hope that my question is clear
Kind Regards
I have got some doubts about the pressure measurement in a water plant.
There are two pressure transmitters, one upstream a centrifugal pump (head = 20 m) and another one downstream the pump.
The measured pressure downstream the pump is lower than that measured upstream. The pressure transmitters measure absolute pressure and not relative pressure and so, the measurement depends on the quote of installation.
How can I compare the two measurement? Which is the height that I have to consider as reference?
I hope that my question is clear
Kind Regards





RE: Pressure measurement
is the pump in operation?
is the pump driver (electric motor ?) connected to the pump?
is this pump new or been in service for a long time?
are the isolation valves at the transmitters are closed?
check the signals from the transmitters to the display monitor - may be swapped if not properly configured.
is there fluid flowing through the pump (i.e. valves not closed)?
there are many potential reasons for this anomaly and all need to be investigated.
good luck!
-pmover
RE: Pressure measurement
RE: Pressure measurement
Sometimes it is water level, sometimes the centerline of the pump, sometimes the floor / ground level. You either need to go and look yourself or get a piping drawing with sections or an isometric to see where the ACTUAL tap off point and transmitter actually are. You won't get this information from a P & ID or a schematic.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Pressure measurement
It doesn't matter if it is absolute or gauge pressure.