Hi pump Enthusiast,
This is internal gear positive displacement pump,i had probably a misconception between slippage and volumetric efficiency. My understanding that volumetric efficiency could be calculated given the theoritical displacement in term of L / revolution of pump. Assuming a theoritical displacement is 6.9 L/ rev. If the actual pump curve indicate operating at 100 rpm to get 30 m3/hr ( actual flow) then the theoretical volumetric flow is 690 L/ min or 41.4 m3/ hr. Since volumetric efficiency = actual flow / theoretica flow * 100 = 30/41.4 =72 % . My questiion
1. Does this volumetric efficiency of 72% is indicating a slippage of 28%, what is the right way to interprate the volumetric efficiency amd calculating slippage in the pump .
2. Does slippage of pd pump damage
The pump, as the fact for slippage the fluid is just recirculatinf from discharge back to suction and so forth result in heating up the pump
Refer to pg 6 and 7
3 NPSHr is givem by manufacturer as the minimum
pressure required at the suction . The justification of pressure loss in pD pump can be justified at the throat area of the suction inlet,Rotor and idler void where the flow coresspomding to rpm, the more flow require more pressure and as rotor rotate faster the pressure loss is greater.
Does operating at faster speed and high viscosity requires higher NPSHr so how manufacturer set its NPSHr does it based on the variation of speed and viscosity so assuming NPSHr for thick liquid of 60000 cps may be higher significantly vs 0.3 cp of Toluene or alcohol
This article shows a good NPSH explanation of pd pump
This is internal gear positive displacement pump,i had probably a misconception between slippage and volumetric efficiency. My understanding that volumetric efficiency could be calculated given the theoritical displacement in term of L / revolution of pump. Assuming a theoritical displacement is 6.9 L/ rev. If the actual pump curve indicate operating at 100 rpm to get 30 m3/hr ( actual flow) then the theoretical volumetric flow is 690 L/ min or 41.4 m3/ hr. Since volumetric efficiency = actual flow / theoretica flow * 100 = 30/41.4 =72 % . My questiion
1. Does this volumetric efficiency of 72% is indicating a slippage of 28%, what is the right way to interprate the volumetric efficiency amd calculating slippage in the pump .
2. Does slippage of pd pump damage
The pump, as the fact for slippage the fluid is just recirculatinf from discharge back to suction and so forth result in heating up the pump
Refer to pg 6 and 7
3 NPSHr is givem by manufacturer as the minimum
pressure required at the suction . The justification of pressure loss in pD pump can be justified at the throat area of the suction inlet,Rotor and idler void where the flow coresspomding to rpm, the more flow require more pressure and as rotor rotate faster the pressure loss is greater.
Does operating at faster speed and high viscosity requires higher NPSHr so how manufacturer set its NPSHr does it based on the variation of speed and viscosity so assuming NPSHr for thick liquid of 60000 cps may be higher significantly vs 0.3 cp of Toluene or alcohol
This article shows a good NPSH explanation of pd pump