Most positive displacement pumps cannot increase output pressure when placed in series as they both stop when they reach their max operating pressure.
22.
An oil diffusion pump is used to achieve higher vacuum ( lower pressure ) than is possible by use of positive displacement pumps alone.
23.
Some continuously variable transmissions use a hydrostatic drive consisting of a variable displacement pump and a hydraulic motor to transmit power without gears.
24.
Second the positive displacement pump backs up the momentum transfer pump by evacuating to low vacuum the accumulation of displaced molecules in the high vacuum pump.
25.
A positive displacement pump must not operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps.
26.
Since the lobes do not make contact, and clearances are not as close as in other Positive displacement pumps, this design handles low viscosity liquids with diminished performance.
27.
A liquid ring pump is a rotating positive displacement pump that is powered by an induction motor and is typically used as a vacuum pump or as a gas compressor.
28.
Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, theoretically can produce the same flow at a given speed ( RPM ) no matter what the discharge pressure.
29.
Positive displacement pumps physically displace fluid, so closing a valve downstream of a positive displacement pump produces a continual pressure build up that can cause mechanical failure of pipeline or pump.
30.
Positive displacement pumps physically displace fluid, so closing a valve downstream of a positive displacement pump produces a continual pressure build up that can cause mechanical failure of pipeline or pump.
