Question about the piping at pumb suction line

Thread407-164412.

A. Then 5 to 10 diameters of straight pipe before nozzle.

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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)

The choice between your options A and B is really just an economic trade off. Option A is low cost/high pressure drop while option B is high cost/low pressure drop. Neither option is universally right or wrong. If you have plenty of NPSH available then go for Option A and save some money; if your NPSH margin is tight you have to pay up and go for option B.

Katmar Software
Engineering & Risk Analysis Software

Dear GOBLINTECHNIC,
I wonder if your envisaged sketches showing orientation(s) in A& B cases are forwarded please!

This might further facilitate in better help& guiding support generation from forum colleagues.

Best Regards
Qalander(Chem)

This is my answer to the same question from another forum:

Reducers, Concentric vs. Eccentric (Revision #13)
The questions:
I am aware of the use of reducers in vertical & horizontal pump piping.
I have consulted with all my Senior Eng regarding this. but I am not able to get an exact reason. My Question is do we use a reducer to avoid cavitation in the pump. I want to know in detail the reason of using the reducer & how does it work in both horizontal & vertical piping.
Please, can anyone help me?

My answer:
First of all the main reason there is a reducer in a pump suction line or a pump discharge line is because the pipe line size is different from the pump nozzle size.
The process engineer determines what line size is required for all lines to perform the function of the process. This is true for both the suction and the discharge lines for pumps. The Pump Engineer specifies and purchases a pump that will perform the function of the process. Due to the nature of the pump, the suction and discharge nozzles almost always (95% of the time) turn out to be one or more sizes smaller than the connecting line sizes. You may ask why they don’t buy a bigger pump, or at least a pump with a bigger nozzle. Well it is pure economics. The bigger pump or the pump with bigger nozzles cost extra money and probably will not perform properly or be cost effective.
So what do we have? We have a pipe line (specified by the process engineer) and a pump (specified by the pump engineer) which needs to be connected. The piping is done by a responsible, well trained, and experienced piping designer. It is the piper's job to know what to do and do it right.
The detailed reason for having the reducer is that good pipers know that to change line size you must use a reducer.
Now, how do you install a reducer?
Vertical lines:
It is okay to use a concentric or an eccentric reducer (flow up or flow down) in vertical lines. You should choose an eccentric reducer when you want to keep one side of the pipe "flat" such as against a wall or group of supports.
Horizontal lines (not at pumps):
It is normal (and recommended) to use eccentric reducers (with the flat side down) for line size changes in horizontal lines on pipe racks. This allows for the different sized piping to have better contact with the pipe supports.
Pump suction piping:
If the pump has a top suction nozzle then you should use a concentric reducer to make the line size change. You should also make the line size change a minimum distance form the pump suction nozzle.
If the pump has an end suction nozzle or a side suction nozzle, then you must arrange the piping so the reducer is top flat and a minimum distance from the pump suction nozzle. The reason for the top flat is this. If the reducer is installed with the flat side down then a "vapor trap" is created by the change in diameter. This space allows bubbles to collect and leads to cavitation.

Now back to your questions. No you do not use a reducer to avoid cavitation of the pump. You use the reducer to change line size. You use the correct installation (orientation) of the reducer in a pump suction line to avoid cavitation of the pump.

PennPiper

I am still wondering what a "pumb" is ???

Turn it upside down. (I mean the first letter)

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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)

SORRY SORRY !!!

PUMB = PUMP

555555555555555555.

thank you for your suggestion.

Take it easy. We're just having some fun with the coincidencial words of the alphabetic characters. Speaking for myself, my Thai isn't all that good.

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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)

There is a paper written a few years ago by Gordon Reddek on eccentric reducers. It is reproduced at the following link