NPSH for the submersible pump

I work for a submersible electric pump company, the only concerns we have with NPSH (In this case, depth of submergence) are with our largest pumps (50 and 90 hp) and then only in the high volume versions (5000 GPM and above). This represented by the minimum head, max flow end of the published curve.

What size pump ( system requirements) are you talking about?

the pump pressure is 200 PSI and 50 cubic meter per hour

i think it is not a large pump

also as you mentioned i should put the atm pressure in my consideration

thanks for you all

I wouldn't worry about it. Sounds to me like you are pumping sea water if there is no vessel or tank. The pump will not cavitate unless you have a filter or something over or around it which might interupt the flow of water.

Thats the beauty of the submersibles, you don't have to worry so much about cavitation and suction losses.

As a sidenote, I like to stick to SI units but some of my older collegues like imperial. Usually when things went wrong it was in confusion between the two. I'd stick to one or the other if possible.

Hi triplex74,

If you are pumping water with normal temperature and your pump is completely submersed in the water,then do not worry about NPSH.If the pump-motor unit is on the ground level and you are lifting water from a pit through a pipe or hose and the water level in the pit is lower than the pump center line level,then you have to take into consideration the suction height and the losses in the suction line up to the pump inlet.Give the suction lift,discharge, head and suction line details to the pump manufacturer,who will select you the suitable pump size that avoids cavitation.

Regards,

Sayed Sarhan