Pump Pit Design for Vertical Turbine Pumps
Pump Pit Design for Vertical Turbine Pumps
(OP)
What are some important considerations when designing a pump pit for vertical turbine pumps? That it should be deep enough to provide the necessary NPSH is a given.
This is for a cooling tower application where there will be 9 pumps lined up over a pit that is 64' wide. Each pump will be capable of 25,000gpm.
Thanks in advance for all the input.
This is for a cooling tower application where there will be 9 pumps lined up over a pit that is 64' wide. Each pump will be capable of 25,000gpm.
Thanks in advance for all the input.
RE: Pump Pit Design for Vertical Turbine Pumps
That is a serious application, I don't mean to bsound rude, but if you are asking questions here, you need professional help. Get an engineer that has done this before for this simple reason that sump design is not easy. Designing one for small flows and simple hydraulics, one can fudge the design without knowing much and it will work most of the time. Something like this sounds like a career breaker.
Bob
RE: Pump Pit Design for Vertical Turbine Pumps
I'm specifically interested in guidelines that dictate pump pit volume. Hydraulic Institute recommends having 2mins of pumping capacity (at max flow rate) in the sump pit.
Why is this? Is this intended as surge capacity in case water supply drops off momentarily? (I wouldn't think so because every system is different) Or is it because having this amount of extra volume will improve conditions in the pump pit leading to maximum pumping efficiency, such as eliminating vortexing tendency?
RE: Pump Pit Design for Vertical Turbine Pumps
You have no idea how strange that sounds. The depth of the sump will only meet it's own requirements. You need to meet the requirements of the system. What goes down must go up.
Ask the PE on the job what he/she thinks.
RE: Pump Pit Design for Vertical Turbine Pumps
If the design is not correct, the fix costs could be major. As a minimum, I would suggest that you check your design with someone that has experience designing successful intake structures.
RE: Pump Pit Design for Vertical Turbine Pumps
RE: Pump Pit Design for Vertical Turbine Pumps
I would have to agree that the design is complicated, but would idsagree that a pump manufacturer would have the slightest idea how to design a sump....
I say this from experience since most of the sumps I have had to retrofit were the result of a pump manufacturer and an industry that did not know how to get the proper engineering for the project. The pump manufacturer knows flange to flange and everything in between, but beyond the pump and into the system is the domain of engineers.
I have seen all to many nightmares in industry from good intentioned manufatcurers that dont have the expertise, but as you said, want to make the sale. Invest in an engineer that does sumps, its a small cost for a system that someone will have to hang their hat on for years to come. Plus, during sump design, different pump choices may come to light that the manufacturer may not bring to your attention if they are trying their hand at the sump design. I look at it as its all how the information for the induaty's project manager and how he makes desisions. Unbiased information being the best there is.
BobPE
RE: Pump Pit Design for Vertical Turbine Pumps
The best you can hope for from the pump manufacturers are several important dimensions: bell diameter, range of distance between suction bell and invert elevation of the intake bay, minimum submergence. All information to help design, but not enough.
RE: Pump Pit Design for Vertical Turbine Pumps
We do not spec systems.
RE: Pump Pit Design for Vertical Turbine Pumps
I have lead a sheltered life, with compedent professional comrades.
Pumper