4 replies to this topic

[Afshin445]

Is it any difference between Intermittent Service pump and Continuos Service regarding
Cavitation issue?

I mean may Cavitation is not occured in Internitent pump service, with Required NPSH
higher than Available NPSH?

I very appriciate if anybody can advise me regarding this issue.

Regards,
Afshin

[djack77494]

Afshin,
Cavitation is related to the fluid, temperature, pressure, and flowrate that the pump "sees". Whether continuous or intermittent is irrelevant - it only affects the time period over which the phenomenum occurs.

[riven]

Afshin,
Cavitation is related to the fluid, temperature, pressure, and flowrate that the pump "sees". Whether continuous or intermittent is irrelevant - it only affects the time period over which the phenomenum occurs.

I would not expect cavitation issue/differences regarding continuous and intermittent service as stated above.

More likely problems could occur if the pump is used incorrectly on the intermittent service such as not being primed properly (if priming is required).

[Afshin445]

Thank you for your fast reply djak. is it mean when condition of Cavitation is available, Cavitation will be occured in one instant, and we need time for this phenomena occuration?

Regards,
Afshin

[djack77494]

Afshin,
I am having a lot of difficulty in understanding what it is that you seek. Regarding cavitation, you could view the possible operating conditions of your pump as a "map". The map shows what regime you will be operating in for different conditions. There are regions of the map where you will experience cavitation. When your NPSHa falls below the NPSHr, then the pump will cavitate and will remain in a state of cavitation until conditions change such that you move into a different regime. What riven has refered to is the possibility of non-steady state behavior during startup of the pump. If the pump has lost its prime, for example, it will be pumping vapors until the prime is restored. If the pump operates intermittently, then there are numerous opportunities for this to happen.