Pump minimum flow calculation
Pump minimum flow calculation
(OP)
I'm new to the site. I was trying to find information on how to calculate/determine minimum flow for a pump and ended up here. Can anyone tell me how to calculate minimum flow for a pump or direct me to help?





RE: Pump minimum flow calculation
RE: Pump minimum flow calculation
Good luck,
Latexman
RE: Pump minimum flow calculation
This subject has been discussed many times in the past. Some examples:
thread407-136129: Minimium flow of pump
thread407-145754: Pump Minimum Flow - mechanical protection
thread407-156557: What is ASpillback
thread407-163975: Pump Sizing with Minimum Flow Return
thread407-167783: Centrifugal Pump Low Flow limit vs. Speed Reduction
RE: Pump minimum flow calculation
RE: Pump minimum flow calculation
Once your minimal flow is established you are able to verify the flow using the pump curve and a pressure gauge on the discharge of the pump. Read the pressure gauge, multiply it by 2.3 and that is the TDH you are imposing on your pump. Find that TDH on the y axis and run horizontally until you intersect the impeller curve. From here move vertically down to the x axis and that is the flow you have.
Of course if you have a positive displacement pump it is a different case. You cannot, cannot, cannot deadhead the pump. Positive displacement pumps almost always have either an integral or installed separately a pressure relief valve. The rating of the pressure relief valve will give you the maximum pressure or minimum flow the pump is designed for. This pressure rating multiplied by 2.3 will give you the TDH. As mentioned above find the TDH on the y axis and run horizontally to the impeller curve you have, run down to the x axis and that is the bare minimum flow you will ever have. Soooo, run a higher flow (less pressure) than that other wise the pressure relief will be going off.
I hope this helps.
RE: Pump minimum flow calculation
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RE: Pump minimum flow calculation
In the Chemical Process Industries I have worked we were usually interested in a continuous minimum flow. I found minimum flow was needed for several applications. That is why I gave the explanation I did.
I have trained operators in plants to use a pump curve. They found using the pump curve a valuable tool in trouble shooting. The information also helped them in situations other than normal operating conditions. I always found the dynamics of operations always demanding and challenging. Excuse me if I confused anyone.
RE: Pump minimum flow calculation
No worries. I also think your explanation is very good. I just saw that nobody mentioned min-continuous in the context of centrifugals and I thought it was worth another $2 input.
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RE: Pump minimum flow calculation
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RE: Pump minimum flow calculation
Thanks in anticipation
RE: Pump minimum flow calculation
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Pump minimum flow calculation
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein