orifice plate & pumps
orifice plate & pumps
(OP)
Good People,
I need another one.
Could anyone explain what benefit could be derived from instaaling a "orifice plate" downstream of a Pressure Relief Valve servicing a Centrifugal Pump?
Regards
'Lekan
I need another one.
Could anyone explain what benefit could be derived from instaaling a "orifice plate" downstream of a Pressure Relief Valve servicing a Centrifugal Pump?
Regards
'Lekan





RE: orifice plate & pumps
If the pump has the wrong curve for the system, it might help keep the operating point somewhere within the pump's efficiency range, but otherwise it will be mostly a benefit to the power company.
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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: orifice plate & pumps
Good answer, but I believe that the OP states that the orifice plate is down stream of the pressure relief valve, not the pump or did I read it wrong?
It may be that the relieving capacity of the pressure relief is such that its flow needs to be reduced.
rmw
RE: orifice plate & pumps
The orifice plate is at the relieve valve downstream, not upstream as Big Inch assumes.
RE: orifice plate & pumps
Mark Hutton
RE: orifice plate & pumps
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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: orifice plate & pumps
RE: orifice plate & pumps
Or it reduces the relief valve flow once the valve opens at its set pressure to reduce the sudden impact of the relief valve opening on the driver.
Lekoso is being rather sparse with the information.
rmw
RE: orifice plate & pumps
Therefore, since the pressure is increased at any given flowrate, the relief valve set pressure must be raised for any given flowrate, as opposed to what it could have been before installation of an orifice plate. Hence, now at any given flowrate, since the inlet pressure to the relief valve must be raised, the flow across the relief valve for any system flow would also be increased over what it would have been without an orifice plate. Result is more outflow into the relief system and less flow to downstream piping than without an orifice plate.
**********************
"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: orifice plate & pumps
What then becomes difficult for me to rationalize is, if the characteristic is somewhat flat left of BEP, then is the PSV required at all? What is the rise to shut-off relative to head at BEP? For pump overpressure protection, the PSV would make more sense to me if the characteristic is steep rather than flat. If such is the case, then this might be a rudimentary attempt at minimum flow recycle.
Therefore, I believe every answer given has merit, but a P&ID with set points and pump curves would be helpful towards providing more definitive comments.
Regards,
SNORGY.
RE: orifice plate & pumps
The psv is needed no matter what characteristics the pump has, presuming there is some component of a lesser allowable than the total normal+transient pressures somewhere in the system.
I'd say it increases any psv chatter, since the system curve would increase more quickly at any given flowrate, thereby forcing the psv to close quicker, but doing nothing else to reduce the pressure, the psv would quickly open again.
**********************
"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: orifice plate & pumps
By "transient", I meant the propensity to somewhat rapidly experience an increase in flow from Q1 to Q2 as a result of the relief valve opening. The extra restriction provided by the orifice downstream of the PSV (which I interpret to mean as installed in the PSV discharge piping) would tend to reduce the flow achievable by the fluid in this path, thereby serving to reduce the magnitude of the change from Q1 to Q2. Perhaps the term "transient" has been used loosely, since it has a very different meaning if one is concerned about something like fluid hammer. All that was meant by "transient" in this instance was "short duration event other than steady state".
"Change in flow rate" would have been a better choice of words.
As for orifice plates not being able to damp out a transient, I do know that when people have trouble with the magnitudes of pulsations and / or undersized pulsation dampeners on PD (plunger) pumps, what is sometimes done is to install restriction orifice plates under and / or adjacent to the pulsation dampeners in the system piping. For whatever reason, that sometimes seems to work in reducing pulsations; perhaps, though, what is also being changed are the system frequency characteristics. So, it may well be true that the orifice plate will not do much to reduce the magnitude of a pressure wave or spike.
Regards,
SNORGY.
RE: orifice plate & pumps
If an orifice plate is "small enough", it could tend to use the capacitance of the adjacent piping as a damper, but I would think that it would be a relatively small diameter orifice that would be needed to do so.
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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: orifice plate & pumps
Again, I need to choose words more carefully when industry-accepted terminology differs from more generic descriptions of words / terms.
I think we (where I work) have been doing too much "crude and close enough" stuff for too long, and it is having an erosive effect on technical correctness.
Regards,
SNORGY.
RE: orifice plate & pumps
what is the use of the oriffic eplate
RE: orifice plate & pumps
In boiler feed applications, many of the automatic recirc valves are fitted with back pressure regulators or fixed orifice plates for this reason.
But this is dragged up from the cobwebs of my mind, and is subject to being completely wrong. This opinion is offered with a 100% money-back guarantee.
RE: orifice plate & pumps
RE: orifice plate & pumps
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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: orifice plate & pumps
the tank but the engineer that has to approved it say that the orrficep plate will reduce the pressure but what about that excess flow. the relief valve is only 1/2 inch. i dont understand his logic behind this.there will be heat built up built and pressure. and the pmp canot shut off and on this is not good for the pump.
RE: orifice plate & pumps
Can you start a new thread for this topic.
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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/