understanding pumps 1

[JTBuer]

I occassionally design small water supply systems (less than 50 gpm). I would like to understand better the pros and cons of various types of pumps and generally the design process in pump selection. Can anyone suggest a good basic practical book?

 

[bimr]

There are several appropriate books listed on the Hydraulic Institutes website:

http://www.pumps.org/

You might be able to find these books as used books on bookfinder.com.

 

[alexkoo]

Hello, I am not a pump expert. But for general application, centrifugal pump would be one of the best and would work better in positive suction head. Simple, cheap and robust.

For pumping from a well, submersible pump, whether oil free or non-oil free(rare, nowadays)would be the way the go.

For constant metering of fluid, peristalic pumpset with tubing being squeezed by a cam.

Progressive cavity pump would be for abrasive fluid such as sludge and lime but the problem of clogging would still persist if not periodically flushed.

Most pumpsets can be driven by VSD(variable speed drive) for coping with flow and pressure head.

 

[HydroJo]

Sorry I cant recommend a book.
But I would advise that in a network the flow rate is dictated by the demands (how much water people take). If you use a fixed speed pump there should really be a header tank so that the pumps can switch off when it's full. Dont pump into a closed pipe system with a fixed speed pump.
If no header tank, small variable speed pumps are now popular which vary speed to maintain constant discharge pressure over a range of demands. BUT for a very small network (4 l/s must be just a few properties)is is probably cheaper to install a fixed speed pump with a small accumulator vessel (pressure vessel with pre-charged bladder).
Tank or bladder vessel are sized to control starts per hour (not more than 12 starts per hour).

 

[bobboulware]

Can anyone suggest a good basic practical book

Contact a local pump sales representative ( Bell & Gossett, Armstrong, PACO etc.) They usually have some good pump selection guides and are usually willing to give you a short course in pump selection.

Regards

Bob

 

[25362]

I'd say the Pump Handbook by Karassik et al., McGraw-Hill, is a good reference to start with.

 

[GrizzlyCurmudgeon]

Karassik as a basic practical book? I don't think so -- it's not for a beginner. Far better is to simply pit a couple competing factory reps against each other, and you'll get enough information from them to understand what's important and what's not.

 

[epbpe]

As a contributing member of the Hydraulic Institute and an experienced water system engineer I feel I can recommend the best class of pumps under 50 GPM and the sources for finding them. First of all, you need to evaluate the required head; an application with less than around 100' TDH is usually best served by a single stage centrifugal pump, while over 100' TDH is best served by a submersible pump. Installing the sub pump in a suction can solves the connection problem. Generating over 100-150' of head in an end suction centrifugal pump requires a large diameter impeller and high speed, which often leads to bearing problems and vibration. Remember that pump efficiency is really the best yardstick we have for selection, a typical centrifugal pump under 50 GPM will only reach around 50-60% efficiency while a submersible pump at the same capacity will reach 60-65% efficiency. The required head is really the best determining factor to decide which pump type to use, always remember that pump efficiency is a factor of pump capacity, not head. Almost all centrifugal pumps (subs or end-suction) will not generally exceed 65% efficiency, this is due to small impeller openings and surfaces. One last thing, stay away from jet pumps, they are the lowest in efficiency, less than 40%! A good source of reference manuals can be obtained from the National Ground Water Association---

http://www.ngwa.org.

Also, most pump manufacturers, such as Goulds, Jacuzzi, etc. offer good selection guides for small capacities. Stay away from HI and other general enegineering references, they are too general and concentrate on larger units.