what is the maximum pump allowable shut off pressure and Max suciton P

[DylanYang]

following is my operating conditions

type: centrifugal pump

liquid: water

discharge: 90 PSIG

suction: -2 PSIG

head: less than 200

NPSHA: 28

Max suction pressure:________

Max allowable shut off pressure_________

i don't know how to do it

could any one give me the definition about above MAX suction and Max allowable pressure.

thnaks

 

[bimr]

Maximum suction pressure is the maximum possible pressure at pump level (considering set pressure of safety valve and/or maximum level and maximum density).The maximum suction pressure is the design pressure for piping, up-stream of pump and compressors. Maximum suction pressure is very rarely specified.

Centrifugal pump shutoff head is the pressure rise against a closed valve on the pump discharge where flow is recirculating in the pump impeller and diffusing spaces and brakehorsepower output of the pump driver is being dissipated by heating up trapped water in the casing.

Centrifugal pump shutoff head is difficult to calculate because of the unpredictable flowpaths of the fluid. Whether or not it is higher or lower than the head at best efficiency flowrate depends on the specific speed of the pump and the tendency toward separation/stalling tendencies of the impeller/diffuser combination that produes either rising or drooping head curve shapes from bep to shutoff flows.

Manufactures may or may not test at full shutoff flow, depending on the extent of the instability there and the danger of damage from overheating the fluid in the casing. If manufacturers tests uncover one or unstable flow regimes at low flowrates or fluid temperature rise warrants, the highest of these flowrates may be designated as the minimum flowrate.

 

[BigInch]

200 what, feet, meters, inches ???

pressure at any given time will be the fluid's Specific Gravity * density of water * Head

The maximum discharge pressure the pump can produce with a given fluid inside can be read from the pressure gauge with the discharge valve closed. Pressure will change with the density of the fluid, but head will not. Get the pressure for one product, convert that to shutoff head, then you can get the maximum pressure the pump will produce with a different fluid inside by adjusting the value of Specific Gravity.

Discharge pressure will also rise by the same amount as when the suction pressure rises.

What would you be doing, if you knew that you could not fail?

 

[stanier]

Site worth learning from is

http://www.mcnallyinstitute.com.

Learn the fundamentals before starting to use automated selection systems.

Once you learn how to do it you could use the

http://www.sulzer.com

or other pump manufactuer's website to select a suitable pump.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[stanier]

This reference may help you.

http://www.pumpfundamentals.com/pump_book.htm

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

 

[rmw]

This thing is multi-posted. I posted an answer in some other forum.

rmw

 

[Artisi]

looks to be a data sheet of some kind, maybe the OP is going out for quotes - just trust someone else is looking over the final selection.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[DRWeig]

DylanYang, please don't post the same question multiple places. Here's a link to the other one, perhaps you can get consolidated answers over there.

http://eng-tips.com/viewthread.cfm?qid=320969

By the way, if you are reading this info from a manufacturer's specification sheet, call him up and ask.

Good on ya,

Goober Dave

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