yes it can be approximated, especially if the casing can be measured as well.
If you want to do it, read a good book on pump design.
I recommend "Centrifugal Pumps" by Anderson or "Centrifugal and Axial Flow Pumps" by Stepanoff. I hear there are lots of other good books.
the "best" act to do is contact the pump mfg and provide mfg with pump make, model #, & serial #. any pump opera data would be helpful. they can then assist you with head and flow.
Hi siamterm, smckennz is correct in saying that a pump's peformance can calculated from the impeller and case dimensions, in effect you will be "reverse engineering" the design.
The amount of effort you put into this should be governed by what you are trying to establish, the physical dimensions of the pump will give you a good indication of its likely performance, ie, if it has a 2" inlet and a 2" outlet and a 6" diameter impeller you know it will not be capable of 75litre/ sec but more like 5 l/sec.
Another way would be to compare your pumps physical appearance with others of known performance.
If you need exact performance, read the suggested books, do a search on the internet for information on pump design or identify the pump and contact the manufacturer.
International College
Naresuan University
Phitsanulok
Thailand
Be careful, performance is affected by many variables. Different types of impellers have different performance, for example a radial vane (Barske) impeller will give different performance than a backswept vane impeller. Open impellers perform differently than closed, etc. If you need accurate performance data, follow tstead's advise and test the pump. Reference the Hydraulic Institute Standards for testing information. If "typical" performance data is sufficient, start by getting the following information from the pump:
Motor Speed
Impeller Diameter (remember, it may be trimmed from it's maximum size)
Pump Casing Inlet Diameter
Pump Casing Discharge Diameter
Manufacturers Name
Pump Model Number
Note that "typically" the pump size is designated as:
(Discharge Diameter)x(Inlet Diameter) - (Max Impeller Dia)
for example 3x4-13 means a 3-inch discharge, 4-inch suction and 13-inch maximum impeller. You can get a pump curve from the manufacturer or there is a website
that has a number of manufacturers' catalog data available to check the size on line. The program is nice in that you can vary parameters and see the affect on performance. Remember that published test data is usually on 1.0 specific gravity fluid (Water) so if your process fluid specific gravity is different, you'll need to adjust the performance data. A good overall reference is the Cameron Hydraulic Data book, available from
