sucking water a lonnnnnngggggg way! doable?
sucking water a lonnnnnngggggg way! doable?
(OP)
Hi all,
I know I need to maintain the min NPSH at the back of a pump (HHW in this case, 80deg C). Could I just pump the system pressure up to a value that will allow me to keep the suction above the min NPSH of the pump? Has anyone seen this done before? I am verifiying a design and the designer assures me that there will be no issues, I agree in theory but I dont like the idea of having unneccesarily high system pressure just to keep the pumps out of a crowded plantroom (thats the reason they are so far away). The set-up is a decoupled primary secondary system with secondary pumps in remote plantrooms (the bypass is in the main boiler plantroom). We have some runs to the back of the pump close to 80kpa dp, others are much lower (< 10kpa). These secondary circuits are going to be interacting like crazy in my opinion.
What do people think?
thank you
I know I need to maintain the min NPSH at the back of a pump (HHW in this case, 80deg C). Could I just pump the system pressure up to a value that will allow me to keep the suction above the min NPSH of the pump? Has anyone seen this done before? I am verifiying a design and the designer assures me that there will be no issues, I agree in theory but I dont like the idea of having unneccesarily high system pressure just to keep the pumps out of a crowded plantroom (thats the reason they are so far away). The set-up is a decoupled primary secondary system with secondary pumps in remote plantrooms (the bypass is in the main boiler plantroom). We have some runs to the back of the pump close to 80kpa dp, others are much lower (< 10kpa). These secondary circuits are going to be interacting like crazy in my opinion.
What do people think?
thank you





RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
Can also, increase the pipe size or reduce flow-rate / pump speed.
Not sure how the secondary circuits are piped in the second part of your question. Maybe provide a rough sketch.
RE: sucking water a lonnnnnngggggg way! doable?
also pump munufucturer is a good reference
RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
BTW, what is a typical fill pressure for a system, assuming the system is all at the same level??
thanks guys
RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
RE: sucking water a lonnnnnngggggg way! doable?
When the primary pump is not running the system will be at the fill pressure. (The suction side to the secondary pump will be at the same fill pressure). If your fill pressure is sufficient for the secondary pumps NPSHR then you should have no problem. When the primary pump is running the suction pressure to the secondary will be higher.