Negative pressure at axial piston pump inlet
Negative pressure at axial piston pump inlet
(OP)
After much Googling, I can't find a solid answer anywhere.
What is the accepted pressure on the suction side of an axial piston pump? There are plenty of charts out there with velocity ranges suggested but no real useful information regarding actual pressure.
Looking through pump catalogues doesn't give too much detail either, not from the ones I have read anyway. I am measuring 0.9 Bar absolute at the inlet to a pump. I want to know how far I am from the limit and what other peoples experiences are in this area.
Thank you.
What is the accepted pressure on the suction side of an axial piston pump? There are plenty of charts out there with velocity ranges suggested but no real useful information regarding actual pressure.
Looking through pump catalogues doesn't give too much detail either, not from the ones I have read anyway. I am measuring 0.9 Bar absolute at the inlet to a pump. I want to know how far I am from the limit and what other peoples experiences are in this area.
Thank you.





RE: Negative pressure at axial piston pump inlet
http://www.launchrun.com/hpd/pdfs/P2P3.pdf
Ted
RE: Negative pressure at axial piston pump inlet
I have used a 7HP centrifugal pump to supercharge the inlet of a 150HP piston pump to meet its NPSHR. I'm not the first person to do that.
Mike Halloran
Pembroke Pines, FL, USA
RE: Negative pressure at axial piston pump inlet
With a charge pump, the minimum for this pump is 0.7 BAR absolute.
As you move below the minimum inlet pressure, the negative pressure on the slippers starts to pull them away from the pistons. That creates a wear pattern, the piston and slipper separate more, which creates a "slapping" motion as the outlet pressure forces them together again. The wear increases until the slippers are pulled off the pistons. Then "BANG", the pump is dead.
Don't go below 0.8 BAR absolute if you want to preserve the life of the pump.
Cheers
HPost CEng MIMechE
RE: Negative pressure at axial piston pump inlet
RE: Negative pressure at axial piston pump inlet
RE: Negative pressure at axial piston pump inlet
It would be impossible to have 0.6 BAR abs on the main pump inlet with a charge pump installed.
Much below 0.6 BAR there is a risk of boiling the oil in the pump inlet. Especially at high velocity and with hot oil.
In reference to kcj's comments on 'gulp factor'...The inlet pipework and the pump casing should be designed to keep the fluid velocity below the maximum even with the pump at max displacement. Also, adding hoses to a pump inlet is asking for trouble. Should always rigid tube.
RE: Negative pressure at axial piston pump inlet
Even with large inlet lines, which we routinely do in mobile equipment due to cold temps, the fluid still changes velocity in a variable flow pump. Larger lines minimize the change.
RE: Negative pressure at axial piston pump inlet