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Dear Ahmed Hamdy

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Not finding these curves HQ displacement pumps, simply because there are no such curves for this type of pump.

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A major difference of displacement pumps is that the flow is independent of pressure!

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A displacement pump while the mechanical characteristics of the equipment resisted this pressure will be a function of engine power and not pressure.

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Imagine, a piston pump when the flow resistance increases should increase the force that drives the piston, increasing pressure, ie there is only increase or decrease the flow rate of the piston to increase or decrease.

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For displacement pumps are dimensioned knowing the maximum pressure (mechanical imposition) and the maximum speed, there is no correlation between one variable and another.

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For me I have taught hydraulics for 37 years is a simple and obvious answer, but your question was motivated by the look in several books I own on the subject (Americans, British, Russians, Brazilians and others) except in a Russian book the answer is given in the middle of a text on mechanical characteristics of displacement pumps, this is the problem of books today, if subtend that everyone knows and show curves for turbopumps, getting drop in the absence of such curves for positive displacement pumps .

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Dear Ahmed Hamdy

.

Not finding these curves HQ displacement pumps, simply because there are no such curves for this type of pump.

.

A major difference of displacement pumps is that the flow is independent of pressure!

.

A displacement pump while the mechanical characteristics of the equipment resisted this pressure will be a function of engine power and not pressure.

.

Imagine, a piston pump when the flow resistance increases should increase the force that drives the piston, increasing pressure, ie there is only increase or decrease the flow rate of the piston to increase or decrease.

.

For displacement pumps are dimensioned knowing the maximum pressure (mechanical imposition) and the maximum speed, there is no correlation between one variable and another.

.

For me I have taught hydraulics for 37 years is a simple and obvious answer, but your question was motivated by the look in several books I own on the subject (Americans, British, Russians, Brazilians and others) except in a Russian book the answer is given in the middle of a text on mechanical characteristics of displacement pumps, this is the problem of books today, if subtend that everyone knows and show curves for turbopumps, getting drop in the absence of such curves for positive displacement pumps .

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The following books may be of interest: Yeaple’s Fluid Power Design HB, Merritt’s Hydraulic Control Systems. Also, when the output pressure increases the back leakage increases through the pump. The connection of pressure and flow is through the power as Professor Maestri has put it.. As far as the hydraulic system flow is concerned and the procedure of modeling you may find some information in the paper

Operational fault diagnosis in industrial hydraulic systems through modeling the internal leakage of its components by Athanasatos.

Dear Ahmed Hamdy.

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It is extremely interesting comment from Theodore, for while pumps flow in a total blockade simply because heating the fluid (in plastic pipes can lead to rupture), positive displacement pumps in a total blockage can damage the sealing of the pump causing damage to the system.

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