Cooling Tower and Condenser Water Pump NPSH Problem
Cooling Tower and Condenser Water Pump NPSH Problem
(OP)
Hello
I have a problem
A cooling tower is installed as the attached drawing with reference to the condenser water pump and HVAC plant room Finished Floor Level.
The NPSH(r) of the pump is 22.5 feet. The water flow rate is 968 gpm.
The place where the system is installed has an atmospheric head of 33 ft.
The head loss due to piping and fittings is 41 ft.
The dimensions given in drawing are in inches.
The pump is posing problems as it is not giving the required water flow rate (due to NPSH problem) and whenever it is shut off, water flows out of cooling tower.
Any ideas??
I have a problem
A cooling tower is installed as the attached drawing with reference to the condenser water pump and HVAC plant room Finished Floor Level.
The NPSH(r) of the pump is 22.5 feet. The water flow rate is 968 gpm.
The place where the system is installed has an atmospheric head of 33 ft.
The head loss due to piping and fittings is 41 ft.
The dimensions given in drawing are in inches.
The pump is posing problems as it is not giving the required water flow rate (due to NPSH problem) and whenever it is shut off, water flows out of cooling tower.
Any ideas??





RE: Cooling Tower and Condenser Water Pump NPSH Problem
What diameter is the inlet pipeline, total length and are the 90 deg. fittings bends or elbows?
Is the pipework drawing a plan or elevation view?
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: Cooling Tower and Condenser Water Pump NPSH Problem
The head loss calculated is with the aid of equivalent pipe length tables for fittings and valves etc and with the assumption of 4/100 ft head loss.
The drawing is a side elevation drawing.
RE: Cooling Tower and Condenser Water Pump NPSH Problem
You need to expand your information into something meaningful if you want answers:
"The head loss calculated is with the aid of equivalent pipe length tables for fittings and valves etc and with the assumption of 4/100 ft head loss" doesn't tell anybody anything as your calculation might be wrong.
Your call - if you want help, supply reasonable information.
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: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
Is it possible to raise the tower or lower the pump?
RE: Cooling Tower and Condenser Water Pump NPSH Problem
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: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
With the OP's system there appears to be something radically wrong with the setup, and until such times full engineering data is supplied it is crystal ball gazing
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: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
However, a correctly engineered installation where there is no alternative other than a lift on the inlet side is / can be done to give trouble free operation.
This is not saying I endorse such an installation, but it is achievable.
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: Cooling Tower and Condenser Water Pump NPSH Problem
In regards to system drain off,can you explain how you will stop it with a NRV?
RE: Cooling Tower and Condenser Water Pump NPSH Problem
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: Cooling Tower and Condenser Water Pump NPSH Problem
RE: Cooling Tower and Condenser Water Pump NPSH Problem
Having 41 feet of suction loss is approximately 18 psi! That's very high. If that is correct, your suction line is too small, too long, and has too many turns.
One of the previous posters was correct in suggesting that every time you stop the pump the suction line will drain to the basis. You can add a foot valve (special type of NRV) to remedy this situation.
I have linked / attached a couple of basic guidelines to help your review.
http://r.search.yahoo.com/_ylt=A0LEVxBDjC9UgmsAqOFXNyoA;_ylu=X3oDMTEzbHU0NXE5BHNlYwNzcgRwb3MDOARjb2xvA2JmMQR2dGlkA1NNRTMzOV8x/RV=2/RE=1412431044/RO=10/RU=http%3a%2f%2fwww.pdhonline.org%2fcourses%2fm134%2fm134content.pdf/RK=0/RS=ZXQGkYYMnVTij39YnRAjGRcSGnU-
Good luck
G.Hartmann
BSChE NC State Univ
RE: Cooling Tower and Condenser Water Pump NPSH Problem
www.pdhonline.org/courses/m134/m134content.pdf
G.Hartmann