PD pump performance 1

[chendian]

Hye,

I would like to seek any expert view.

If i want to buy the positive displacement pump, do I need to provide the NPSHa value?
And what is the impact to this pump performance if the NPSHr value is higher than NPSHa?

Thank you.

 

[LittleInch]

Yes you need to supply all relevant data

If NPSHA < NPSHR, the pump may not work, could suffer damage or at the least performance would suffer.

Different PD pumps have different capabilities for NPSH.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[chendian]

Thank you for the feedback.

FYI, the medium transfer is fuel with viscosity about 20cSt at 20degC.
With PD pump gear type, why this pump couldn't work if the NPSHa<NPSHr?

Is it because of the cavitation will be occurred at the inlet pump?

Or pressure loss in the pipeline resist the pump to operate?

 

[LittleInch]

It might "work", but could be pumping a mixture of liquid and gas. A gear type unit would just make a lot of noise and not produce the flow or pressure it was designed for. Over any reasonable time period ( days / weeks) this could easily damage the unit at which point the pump vendor will not take responsibility as you've been operating it outside the required inlet conditions.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[chendian]

Tq