POSITIVE DISPLACEMENT PUMPS

[marineengineer123]

Hi all,
one question,
Why do some positive displacement pumps NOT require a pulsation damper?

 

[hydtools]

Pumps don't care if they have a pulsation damper. System designers or system users may.

Ted

 

[Pumpsonly]

There are many types of PD pump mainly into 2 categories based on the pumping action

1) Rotary type such as..twin and multi screw, progressive cavity, gear , lope

2) Reciprocating..plunger , piston

Most rotary PD pumps do not need pulsation dampener because of the very low or almost zero pulsation flow.

Please Google for the various pump type to understand their pumping action and see for your self why a pulsation dampener is needed in a system with reciprocating PD pumps.

 

[nucleareng78]

this may be off-topic. But as a general rule, does the NIPR of a PD pump INCREASE as the pump becomes older. Let's say we have a 20 year old PD pump with a certain NIPR, wouldn't the NIPR be greater due to the internal parts wearing down?

 

[micalbrch]

NIPR? What is that?

 

[nfinit]

net inlet pressure required...

 

[hydtools]

nucleareng78, I had not heard of that general rule. It would seem that as a pump wears, net delivery would be reduced therefore less fluid is delivered and less requirement for inlet pressure to push fluid into the pump inlet. Just the opposite, in theory.

Ted

 

[TPL]

Maybe there's confusion with NPSHr?

 

[nucleareng78]

NPSHr is basically the same as NIPR, but PD pumps primarily using the NIPR terminology.

NIPR (psi)
NPSHr (ft WC)

Different units

 

[jardelviana]

only pump that have pulse like (AODP, peristáltic, etc...), pump that use screw, gear, lobe don't need pulsation dumper because normaly work with laminar flow.