Level lowering of pump station
Level lowering of pump station
(OP)
Hello,
When designing a pump with a specific HMT (123 m), and we come across a client update (lowering the pump level ΔL=-1.6m),
Suction tie-in point ( with Residual pressure Pr = 15 m minimum) and discharge point elevation are still intact.
Do we need to update the pump spécification : HMT = 124.6 to make up for the loss in elevation
or it is all the same since as we lose in the discharge, we gain in the suction line
Please find attached a simple image to explain the situation

When designing a pump with a specific HMT (123 m), and we come across a client update (lowering the pump level ΔL=-1.6m),
Suction tie-in point ( with Residual pressure Pr = 15 m minimum) and discharge point elevation are still intact.
Do we need to update the pump spécification : HMT = 124.6 to make up for the loss in elevation
or it is all the same since as we lose in the discharge, we gain in the suction line
Please find attached a simple image to explain the situation






RE: Level lowering of pump station
By the way, what is HMT? I assume this means something in French?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Level lowering of pump station
RE: Level lowering of pump station
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Level lowering of pump station
RE: Level lowering of pump station
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Level lowering of pump station
RE: Level lowering of pump station
HMT in indeed a frech designation for the " total discharge head "
Hears the situation:
We have a pump with a BEP (1100 l/s ----> 123 m) demanded by the client (assuming that he did his topographic mesurments accurately for the discharge head "123 m").
Now the pump level must be lowered down because he decided that the pump suction line have to be burried.
The pumpe BEP is a contractual detail and must be respected, therefore, we need to know weather lowering the pump level affects it's ablitily to provide 1100 l/s @ 123 m head.
In pumping systems, we have the following formula: System head = total discharge head - total suction head
Should this formula be a convincing reason to keep the pump caracteristics ? (Basically the discharge head lost due to lowering the pump level, is gained in the suction line)
Hears a sketch to explain the situation
RE: Level lowering of pump station
The extra 1.6m required on the discharge head is matched by the extra 1.6m on the inlet head. The pump has to do the same work. I think you can ignore any minor additional friction in the extra pipe length.
When you say "system head" most people call that TDH or total differential head.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Level lowering of pump station
Cheers,
John
RE: Level lowering of pump station
RE: Level lowering of pump station
Hears below a link to a website that elaborates cleary the calculation procedure for future references:
Link