Increasing NPSHa

How can i increase NPSHa in a cooling water system.

What scope is there for extending the pond walls upwards and increasing the water level?

That's a lot to increase NPSH but an inducer may help.

Can you simplify the piping to the suction thus reducing frictional losses e.g fewer bends?

Is it possible to position these pumps below ground level [in a pit] and thus obtain the additional NPSH [I had to do this recently, as the conventional condensate extraction pumps were too costly]

Or increase the size of the pipes on the suction end.

Sounds like some pretty big pumps so getting more suitable pumps is probably out of the question? Pipes are expensive too but just a thought anyway.

NPSHa can be incresed by reducing the frictional losses in the pipe or discharge should be below the suction level. if your suction side above the water level then it can also helping to incresing the NPSHa

Sounds like you need a submereged suction pump of slightly more capacity and slightly more head then the npsha delta. A better description of the task would be nice. Typically all of the bad crap happens to a pump on the suction side for that reason the design of any system should allways advantage the suction side of the pump. If you are recirculating from a pond then put the pump in the pond. If you have a loop, put in a 24 inch dia. vented stand pipe and put the pump in it. In each case submerge the pump in a vented suction application.

oops Since it will take a 24" verticle turbine or so ....use at least an 8ft dia. stand pipe or tank. Anything else is a gamble.

Try to measure the water level above suction line of pump. NPSH is 7 Meters mean theoretically you can lift water from a depth of 7 meter- friction loss. from the pump.Also this is mentioned is the design catalogue of pump. Some how increasing the pipe size will but I feel if the design can not change , you have to submerge the pumps 3 meters down looks like submersible pumps.

You have to define the problem in details- water level, pump suction level. groud level etc.

Depending on the system you have, it would be possible to do one or more suggestions posted above. Since you are the only one who knows the configuration, could you provide further information details?

Maybe will be easier if you try with other pump which has the adequate NPSHr (NPSHr>11m). Normally this is the way to do that.

SaC.