Centrifugal Pump Selection

Pump Selection System - PSS - - Goulds Pumps - ITT Corporation

The total head includes the discharge head , suction lift and suction losses.

Please correct me if i am wrong, suppose my desired head is 130m and the reading on the pressure guage where the pump to be installed is 1 bar (10m),

then the total head will be 130-10=120m

so now based on my required (H,Q) where should i select my point in the performance curve?

my sincere thanks to all your inputs

You seem to have a booster type of operation going there.

The pressure available at the impeller is not destroyed and that pump or stage is just responsible for its contribution to the (additional) pressure.

We don't have enough information available to comment on your figures.

let me rephrase my question again

my objective is to buy a pump that gives 130 m discharge pressure and 50 gpm flow, yes its booster pump. grundfos make.

what information should i give to the supplier to get the correct pump size.

can i give them the discharge head or the total head?

the suction head is positive.

You need to know what is the pressure losses due to the flow of 50gpm in your pipe lines.

If these losses are negligeable then give them the 130 - the NPSH (10m ?), but if you are sure there will be some losses and the NPSH = 10m only for the 130m, then give them the 130m. The positive suction head is negligeable and will compensate some of the losse.

Since there will be a flow of 50gpm at 130m, then you might have some reserve pressure available from the pump. IT ALL Depends on the pump Curve at the operating point on the curve.... pump model. It is not so simple to advise and select for you. You need to look at different pumps with near similar discharge / pressure and chose the one that will accomodate any variations your system will encounter during operation and how critical the 50gpm is for the process.

It is nor clear where the 10m positive pressure is from.

If it is an overhead tank or another pump then it is acceptable but the NPSHA cannot be deducted from the duty point (you have the same pressure to overcome at the discharge point)

No losses should be taken as negligible either.

If you just want a suitable pump and you don't want to do the calculations yourself then try a supplier like Grundfos. When I used them about 5 years ago all you did was tell them your system and what you need and they work it all out for you and suggest what pump would be best.

I haven't worked with pumps for ages so can't remember off the top of my head all the equations. Also make sure your NPSHa isn't too high.

Total dynamic head, TDH, is more descriptive and is the term you'll find when referring to pump manufacturers' performance curves. In a closed system the TDH is the sum of pressure drop in the the piping system caused by pipe friction. In an open system TDH will be the sum of the actual lift or difference between the fluid level on the suction side of the pump and that on the discharge side. Add to that the friction loss in the piping. TDH is usually expressed in feet of the fluid being pumped. The manufacturers' curves will show gallons per minute, GPM, on the horizontal ordinate and TDH in feet on the verticle.