Irrigation Pumps, Suction-Discharge, and Filters

It is hard to give you a definite answer without more information regarding NPSH, flowrates, pump charts, and piping details. (also could you attach a sketch of your system?)

You may have a problem - or you may not have a problem.

I am going to assume that the pipe gets larger before the filter (is it really a filter suction, or simply an inlet?) to drop the velocity and increase pressure. This is probably not a problem at all and may be preferred (save money on larger pipe and meet the operating requirements of the filter).

Typically pump suction piping is oversized from the pump suction nozzle to minimize friction loss (velocity) and avoid cavitation problems. But this may not be an issue because you may have more than adequate NPSH_A or your pump does not have a high NPSH_R.

So, to repeat, with so little information it is hard to give you an answer.

"You may have a problem - or you may not have a problem."

If it isn't broken, don't fix it. If there is a problem or if the system seems noisy, let us know. Provide info on pump nameplate, estimated flow rates, pressure gage readings, motor current, anything you can find, and some one may post a solution or suggest changes for you. What is source of water, and how high are you pumping it?

Thank you very much for your answer.. I will try to send you a sketch.. i want to ask smth else..when we say friction head loss across the filtration station downstream of the pump set should be 3-4mtr what does this mean?