Flow and Pressure Through Stand-By Centrifugal Pump

Suction pressure and no flow. TGIF

Guest : Original Poster.

Does it mean, centrifugal pump may be considered similar to reduced bore pipe. And if test valve, which is before check valve,to be opened shall dischrge water approximately at suction pressure level of pump and flow corresponding to test valve opening cross-section.

Good day.

The Prof's answer told you everything you need to know to answer your original question. If there's a test valve, that makes a difference. Why didn't you say so before?

Codey

Refer to the manufacturer's performance graphs for this particular pump.

excuse for my ignorance. Im still learning english and Im studing engeenering but i can not find the relationship between the words to undertand what do you mean with a "Stand by pump" can you please tell me where can i find information about it. Thank you very much!!!

Usually in continuous operations we provide standby systems. Systems are programmed in such a way that after certain period of running the pump the system will over to other pump. This is the meaning of standby. In some applications standby system are provided to carry out the maintenance of the other equipment without disturbing the system operation.

Hi

I have gone through your question, I would like to correct you here. Parallel operation is to boost the flow not the pressure. If the sandby pump is working alone , then it is like a normal pump. If both the pumps runs in parallel, the head and flow will get shifted depending upon the system resistance. To find out the exact point , draw a parallel operation curve along with system resistance curve. The intersection point of these two curve will give you the new duty point.

Hope this will Help.

If the suction valve is closed and the discharge valve is open, the fluid passing thro check valve/NRV (these are not leak proof), will build up discharge pressure up to the suction isolation valve. Some suction lines are damaged due to the lack of consideration of this aspect.

Agree with b v rao. "Ideally", if the check valve is not leaking the test valve will only see the suction pressure. But in many cases, the check valve is not fully isolating, and therefore the pump can see high pressure.

If the suction valve is also open this will lead to reverse flow (which is damaging to the pump is not designed for reverse flow). If the suction valve is closed, then there could be a high pressure scenario. I will be careful before opening the test valve particularly for high pressure pumps, even if it is upstream of the check valve. Consider providing a thermal relief valve between the suction valve and the check valve!