## Maximum velocity and pressure drop limits for pumps piping

## Maximum velocity and pressure drop limits for pumps piping

(OP)

Could I get guidance to find out the capacity of light hydrocarbon lines (butane) both for centrifugal pump suction and discharge piping?

What is the industry standard for maximum velocity and pressure drop limits. I know API RP 14E recommends 3 ft/sec and 9 ft/sec max for velocities for suction and discharge lines. Hydraulics Institute is less conservative to choose the numbers.

We have two pumps in parallel taking butane product form storage sphere. We need to find out how much more liquid can be pushed through this line?

Your comments will be highly appreciated for a newbie in the industry and this forum as well.

What is the industry standard for maximum velocity and pressure drop limits. I know API RP 14E recommends 3 ft/sec and 9 ft/sec max for velocities for suction and discharge lines. Hydraulics Institute is less conservative to choose the numbers.

We have two pumps in parallel taking butane product form storage sphere. We need to find out how much more liquid can be pushed through this line?

Your comments will be highly appreciated for a newbie in the industry and this forum as well.

## RE: Maximum velocity and pressure drop limits for pumps piping

Probably around 20 fps as a liquid, not applying to pump suction lines. It may depend more on what pressure drop you can allow in the piping. Do not drop the pressure below butane's vapor pressure anywhere in the piping, especially suction lines. That varies from around 1 Barg at 5C, to 4.5 Barg at 50C.

60 fps as a gas.

You may find some helpful info here too.

http://www.corken.com/publications/training.html

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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

## RE: Maximum velocity and pressure drop limits for pumps piping

Butane is stored as LPG so in liquid form and is always be in the boiling range. We have 25-30 ft suction head available all the time through the storage sphere liquid level so have some room for pressure drop in the suction line.

Don't you think 20 ft/sec limit is on the higher end for most on-plot lines (not pump suction).

Regards

## RE: Maximum velocity and pressure drop limits for pumps piping

**********************

"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

## RE: Maximum velocity and pressure drop limits for pumps piping

Thanks for your valued comments.

I have one other issue.

We have a second pump which is getting Isobutane charge from the pump as discussed.The second pump is about 250 feet away from the first pump and is Vertical Turbine type.

Not sure whether suction pressure of this pump needs to be above vapor pressure all the time or will need to have only the static head required in order to avoid two phase flow/ pump cavitation.

Also as both pumps are on the same grade level so may not have static head available. What would be the NPSHA (equation) for this pump. Line loss in this pumps' suction line is about to 2 psi.

Regards

## RE: Maximum velocity and pressure drop limits for pumps piping

**********************

"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/