Reason for specifying suction pressure
Reason for specifying suction pressure
(OP)
While data sheet for centrifugal pump is prepared suction pressure and npsh available are provided . I understand npsh available takes into consideration of atmospheric pressure, ( if applicable) minus the vapor pressure and minus the friction losses . In that case , please let me know is it not this npsh available matters to the pump to work with ? Then why we need another parameter suction pressure which is simply the static head converted to pressure or pressure available near suction flange , depending on case to case?





RE: Reason for specifying suction pressure
Maximum suction or inlet pressure is more about what is the max pressure the pump seals see if the inlet valve is open but you have no flow.
For something like a booster pump in a pipeline or many other systems, the static no flow inlet pressure can be significant even though inlet pressure in operation might be much lower and the pump seals need to be good enough not to leak at that pressure.
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RE: Reason for specifying suction pressure
RE: Reason for specifying suction pressure
RE: Reason for specifying suction pressure
It's also used to calculate the pump thrust, also required for the mechanical seal (and system, if applicable.)
RE: Reason for specifying suction pressure
Pump 1 is discharging 2000 psi. Next pump in the line is pump #2 and it is seeing 1750 psig from pump 1 after subtracting 250 psi line loss through the 50km of pipeline between them. Better be sure that pump #2 can take at least 1750 psig, and maybe the full 2000 pisg when flow from pump #1 is slow, or stopped completely, as pump #2 might see full discharge pressure from pump #1 in these types of installations.
RE: Reason for specifying suction pressure
Basically yes - it is the seal issue which is important for max inlet pressure. The other issue is also at pump start, the pump might then have a momentary very high discharge pressure until the inlet pressure reduces to its "normal" pressure. Also if the outlet valve is closed (no flow), the discharge pressure could easily exceed a class rating if your "normal~" discharge was close to it (say 90 barg for a class 600 system). The pump could then need to be designed for a much higher pressure than its rated or normal discharge pressure.
Rated pressure affects the pump casing design.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Reason for specifying suction pressure
RE: Reason for specifying suction pressure
RE: Reason for specifying suction pressure