Suction Pressure: Maximum vs Rated
Suction Pressure: Maximum vs Rated
(OP)
Dear all,
I would be grateful if you could help me with a basic question about centrifugal pumps: which is the difference between the maximum and the rated suction pressure?
Thank you for your time.
I would be grateful if you could help me with a basic question about centrifugal pumps: which is the difference between the maximum and the rated suction pressure?
Thank you for your time.





RE: Suction Pressure: Maximum vs Rated
Maximum suction pressure is the rating of the pump's suction flange, or possibly some other factor which limits suction pressure to the given maximum value.
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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: Suction Pressure: Maximum vs Rated
Maximum suction pressure could be two different things: it could be the maximum suction pressure that the pump could see, as specified by the plant/engineer/user, for an upset condition.
OR
It could be the maximum suction pressure that the pump is capable of withstanding, based on the operating speed, so that the pump does not exceed its own pressure rating. This would be the maximum suction pressure as specified by the pump manufacturer (not as commonly seen as previous meaning).
Most commonly, the engineer will specify the maximum suction pressure that the pump is expected to see, so that the pump manufacturer can select a pump that is capable of withstanding that pressure.
RE: Suction Pressure: Maximum vs Rated
Johnny Pellin
RE: Suction Pressure: Maximum vs Rated
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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: Suction Pressure: Maximum vs Rated
I will refer to the TenPenny explaination in which he defines the "maximum suction pressure" as the maximum pressure that the pump could see for an upset condition.
RE: Suction Pressure: Maximum vs Rated
Max pressure is max pressure. Doesn't matter if it is an upset condition or not.
**********************
"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: Suction Pressure: Maximum vs Rated
The maximum suction pressure could be calculated as the sum of the set pressure of the psv (the design pressure of the tank/vessel in most cases) + the head @very high level - pressure drops (pressure drops have to be taken into consideration in this case?). I have considered this last condition as an upset condition because it is different from the "normal" condition. Isn't a correct interpretation?
RE: Suction Pressure: Maximum vs Rated
AND
That's fine, as long as you include OFF as an upset condition.
For example the way you are calculating maximum suction pressure would not give the maximum suction pressure in one of the two most very normal conditions ON, or OFF. In the OFF condition, you would not have suction line losses and, if that was a butane tank, the sum now might easily be enough to put you over the limit of a lot of maximum flange pressure ratings. If you speced the pump max suction pressure in that manner, I can assure you that it is very possible you would get a flange that didn't work when the pump was OFF. Not nice.
I don't see the real use of the term, maximum suction pressure, for anything other than a flange rating anyway. If suction pressure's head equivalent is above NPSHR and below flange ratings, who cares what it is. Change product and a previous suction pressure or discharge pressure doesn't mean any thing at all. Pressures change with specific gravity. That's why specing a pressure really only means something to pumps when applied to FLANGE RATINGS and other components.
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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: Suction Pressure: Maximum vs Rated
ht
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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: Suction Pressure: Maximum vs Rated
RE: Suction Pressure: Maximum vs Rated
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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: Suction Pressure: Maximum vs Rated
I will defer to your preference. You can take the topic and run with it.
RE: Suction Pressure: Maximum vs Rated
I thought it was run out back then. What more do you really need to say.
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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: Suction Pressure: Maximum vs Rated
In vertical pumps, or vert in-line pumps, max suction pressure can also be the max pressure to prevent an up thrust condition and maintain 2 yr L10 bearing life.
Did you know that 76.4% of all statistics are made up...