Motor selection for Positive displacement pump

[vanuta]

Hi,
I am trying to size a correct motor for my pump. The setup will be, a motor connected to a reduction gear box and the gear box will be connected to a positive displacement pump. The process undertaken is as follows:

1) Look at the different pump ranges ( Flow and Pressures). From the Flow and Pressures, i will be able to determine the HHP required for the pump. I will also need to look at the pump rpm. Let's take an example. I am trying to pump 10 gal of chemical at a pressure of 100 psi. In this instant my HHP required = 10*100/1715 = 0.583 HHP. Let's say the pump speed is about 100 rpm and the reduction gear ratio is 5:1.

2) In the above case, the motor rpm has to be 100*5 = 500 RPM. Assuming the efficiency is 80% , which means to say that my motor has to input 1.2*0.583 = 0.7 BHP. Am i correct to say that as long as my Motor curve shows a power output greater than 0.7 BHP @ 500 RPM, the motor is good for this application?

Do i have to consider any other factors ( e.g Torque on the motor curve etc...)or just BHP check should suffice. Any advice is very much appreciated.

Thanks.

 

[mk3223]

From the HP point of view, the calculation of BHP is adequate for the pump design.
The next step is to need a quality EE to select a proper motor based on the operation conditions, such as low/high operation cycle, indoors vs outdoors, power source, environmental, etc. Or, you may contact the pump vendor to select for you per your operation conditions.

 

[ashtree]

500pm is not a standard motor speed so we would have to asasume you are going to operate with a VFD to control the motor speed. You will need to select the appropriate VFD for this application and then review the motor selection to ensure that it can provide the torque required at the speed and that motor cooling will be adequate.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[LittleInch]

I think you're putting the cart before the horse here.

Try finding a pump and motor package that does your duty rather than arbitrary rpm discussion.

Also 10 gals per what. Second, minute or hour??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

https://www.eng-tips.com/viewthread.cfm?qid=260444

MJCronin
Sr. Process Engineer