8 replies to this topic

[Sardar]

Dear members,

 

Hope you all are doing well.

 

I read the statement regarding Internal gear PD pump " The internal gear pump is non-pulsing, self priming and can run dry for short periods. " 

 

As per my understanding self priming pumps are the pumps that are capable of removing air from pump and can start pumping liquid by there own. I need to know whether there is some pressure limitation for self priming as well or not.

 

Thanks in advance.

[fallah]

Sardar,

 

PD pumps are generally self priming pumps...but nevertheless:

 

PD pumps manufacturers normally supply info on minimum suction conditions, included pressure, which are required especially on high lift or high vacuum cases. Then you can ask relevant vendor to provide such info, if you want.
 

[latexman]

In our process, we fill and empty small tanks with PD pumps 2-4 times a day.  After re-filling a tank, we prime the pump until steady flow is verified by recirculating back to the tank with all valves in the flow path wide open.  Then, we align the valves to run to process (no priming).  This is all automated.  It was the most expeditious and trouble-free way we found to prime the pumps.

Edited by latexman, 07 November 2017 - 08:43 AM.

[Sardar]

Gents,

 

Thanks for your help.

 

Dear Naser Fallah

 

Vendor has stated that "Self priming is up to 950 mbar" so does it mean that pump can operate at minimum of 13.77 Psia suction pressure?

 

Thanks 

[fallah]

Sardar,

 

Yes, that minimum suction pressure is required for mentioned PD pump to have self priming characteristic.

[Sardar]

Thanks a lot Fallah for your help.

[latexman]

Are you sure it means "minimum of 13.77 psia suction pressure"?  I'd call the vendor and ask them to show/explain exactly what "self-priming is up to 950 mbar" means.  The reason I say this, we use a good many PD pumps, including internal gear pumps, like Viking.  Their literature on their rotary gear pump says "some Viking pumps are capable of suction lifts up to 20 feet (6 m).  This would imply a suction pressure of 6 psia.

 

Maybe it means self-priming is up to 950 mbar of lift, or 31.8 feet (9.7 m).  I know some of our sliding vane pumps are capable of this.  It seems to be a stretch for a rotary gear pump, but a 13.77 psia suction is only a 2 ft. lift.  That is not so good.

 

It could be your application is unlike mine and I'm off base, but I thought I'd bring it up.

[Sardar]

Dear Latexman,

 

Thanks for bringing another aspect. I will contact with vendor and will try to make it more understandable.

[latexman]

Ask them how much suction lift is guaranteed/warranted.