PD pump piping "best practices"... 3

[Zylinderkopf]

Season's Greetings, fellow Engineers:

Please be advised that I had originally posted this question at the "pump engineering" forum and hope to obtain at least one (1) response from this forum (hope that my questions are easily understood and even warrant a response...).

Screw-type pumps will be installed at our site in a lube oil system. Are there existing standards/best practices for screw-type PD pump piping, not unlike WRC 449 and like standards published by the Hyrdaulic Institute utilized with Centrifugal-type pumps?

Also, may I prudently consider Rupture Discs for the overpressure device that is typically installed in way of the PD screw-type pump discharge?

Any assistance that any of you afford me will never be taken for granted and will always be appreciated.

Thank you for your time and kind consideration of my enquiry.

Pete

 

[chief]

Screw type pumps normally have a relief valve in-built which relieves back to the suction of the pump. There is an adjustment arrangement for setting the delivery pressure.
Rupture discs are not a good idea. If they burst, you will have hot oil spraying around your area, which will cause injury to any personnel in the vicinity and is also a fire hazard.
The relevant codes of practice I do not have to hand right now.

Offshore Engineering&Design

 

[Zylinderkopf]

Greetings, "Chief":

Please accept a "star" for your advice in way of the safety issue that you had pointed-out to me as it pertains to installting Rupture Discs in the subject application.

Please do not go too far out of your way to find materials that sddress PD pump piping...I have done, what I belfive is, an exhaustive search on this topic and I could not find anything.

Thank you for your time and kind consideration of my enquiry.

 

[RossABQ]

You may find some "typical" practices if you search on Fuel Oil piping systems. These are also typically PD-pumped, and have similar requirements. When you say "screw-type" pumps, do you mean gear pumps?

I would avoid recirculating back to the suction on a pump of any size. Better to use an external back-pressure regulator that dumps to a return line going back to the reservoir. If there is a chance that the pump could remain running with nowhere to send oil, this will avoid overheating. Many engine oil systems do this so oil pressure can be "proved" prior to starting the engine, by runnning the oil pump independently of the engine. On turbine engines and standby generators, this is sometimes done so the oil can be heated and filtered without flow to the engine.

 

[Zylinderkopf]

Greetings, "RossABQ":

Please accept a "star" for your advice in way of considering Fuel Oil piping systems as analagous to LO piping systems...I had not thought of that; thank you!.

Thanks also for your cautionary words in way of pump recirculation issues, and for your descriptions of ICE, turbine engine and stand-by generator systems...very nice.

As an aside to your question, I should have been more clear about my use of the term "PD screw-type pump". I was sincerely hoping to describe the subject pump type as:
"a special type of rotary positive displacement pump in which the flow through the pumping elements is truly axial" (Ref: Karassik, et. al.); as such, I had not intended to describe a "gear-type" pump.

Thank you for your time and kind consideration of my enquiry.

 

[hydtools]

Here is an article about matching the lube system to the machine. The charts reference gear pumps, but screw pumps could be substituted. Some of the information could be useful to you.

http://www.machinerylubrication.com/article_detail.asp?articleid=687

Ted

 

[Zylinderkopf]

Greetings, Ted:

Please accept a "star" for your article referral and for your time and kind consideration of my enquiry.