Gear Pump Sizing

[RJB32482]

Hi,
When sizing a gear pump, does discharge head play a role in sizing the pump? I looked and saw that the flow rate depends on the RPM and the horsepower of the motor. It also states this at a different pressure (ex. 0 psi and 100 psi). Is this pressure the discharge head? If not, what does this pressure correlate to?

First time sizing a gear pump. Thanks.

 

[checman]

Just some basics on gear pumps. Normally only used on lubricating fluids. Special materials, designs and de-rating can overcome this restriction for some models. Most are positive displacement or PD pumps. Rotary positive displacement pumps displace a certain amount of fluid per revolution. RPM x displacement minus slippage equals capacity. The amount of slippage is heavily influenced by viscosity and to some extent RPM. Different types of gear pumps have different pressure limitations. For instance internal gear pumps normally have an over hung rotor and cannot develop the pressure of a between bearings external gear. GPM, pressure and efficiency determine horse power. Check with your OEM for this type information on the pump you are looking at.

Regards checman

 

[RJB32482]

So what is the "pressure?" Is it discharge head?

 

[checman]

Yes when I am saying pressure I am talking about discharge head. Remember that when you are calculating horse power you need to use total dynamic head. Also when I spoke of slippage I forgot to mension that discharge pressure is also a major factor.

Regards checman