selection of booster pump in order to provide NPSHr for main pump
selection of booster pump in order to provide NPSHr for main pump
(OP)
hi every body,
we want to select the booster pump to supply the required NPSH for main pump.
main pump:
NPSHa = ATM
NPSHr = 5bar
suction pressure = ATM
Discharge pressure = 37 bar
what shall i considere to select the booster pump for this application?
1- i think that the flow of booster pump shall be equal to main pump, what a bout the head of booster pump?
2- when these two pump operate in series, can we sure that they work in compatible with other?
3- is it possible we select the screw pump as booster pump since our main pump is centrifugal?
regards,
we want to select the booster pump to supply the required NPSH for main pump.
main pump:
NPSHa = ATM
NPSHr = 5bar
suction pressure = ATM
Discharge pressure = 37 bar
what shall i considere to select the booster pump for this application?
1- i think that the flow of booster pump shall be equal to main pump, what a bout the head of booster pump?
2- when these two pump operate in series, can we sure that they work in compatible with other?
3- is it possible we select the screw pump as booster pump since our main pump is centrifugal?
regards,





RE: selection of booster pump in order to provide NPSHr for main pump
Do not mix up pressure and NPSH. That are two different things.
RE: selection of booster pump in order to provide NPSHr for main pump
Johnny Pellin
RE: selection of booster pump in order to provide NPSHr for main pump
first of all i want to know what shoud i considere to select the booster pump? flow,head,speed,power and ....?
becuse of low NPSHa for bosster pumps we have a option to select screw pump as bosster pump. do you recommend screw type pump as a bosster while our main pump is cenrifugal?
RE: selection of booster pump in order to provide NPSHr for main pump
You can also use a PD pump(e.g. Screw type) as booster pump, as long as considering its pulsation. It means you need to check with manufacturer to see the minimum discharge pressure.
Hope this help
By the way, don't forget to put PSV upstream of your main pump, and its set pressure should be minimum of yield pressures of either of two pumps' casings.
RE: selection of booster pump in order to provide NPSHr for main pump
The screw / PD pump will behave like a throttling valve and cause cavitation when the CP is trying to push more flow through the pipe line when there is a drop in down stream pressure.
The booster pump must be sized to have the same capacity range as the main pump with the discharge pressure/ head to provide adequate NPSHA to the main pump + the head losses on the piping between the 2 pumps.
RE: selection of booster pump in order to provide NPSHr for main pump
i have a same idea as pumpsonly.it is very difficalt to use PD pumps as booster. but in case of emergensi, can we use screw pump with considering the by-pass flow for screw pump?. for example when main pump work in low flow,we by pass some flow of booster pump to downstram? do you think any more criteria or problem that my be happen during operation?
RE: selection of booster pump in order to provide NPSHr for main pump
I mixed up because the other way around is right, I mean a centrifugal pump as booster pump for a PD pump(Ref: Karasski section 3.81).
Sorry again for misdirecting.
RE: selection of booster pump in order to provide NPSHr for main pump
i think the only problem is flowrate when we use PD pumps as a bosster pump. with considering the by-pass line from dischare of PD pump to tank, can we solve this problem? is there any more problem except flowrate?
thank again
RE: selection of booster pump in order to provide NPSHr for main pump
re your last posting, you will nave to over size the PD pump to cater for the maximum possible flow of the CP.Why are you so insisting of using a screw pump? Some Progressing Cavity (PC) pump sales guy might have told you a PC pump can be used a booster because of the low NPSHr.
RE: selection of booster pump in order to provide NPSHr for main pump