Ball valve flow rate & pressure drop
Ball valve flow rate & pressure drop
(OP)
In ball valve is Bernoulli principle used to estimate the values flow rate & pressure drop estimation
And what will be the difference with ventury flow path & Straight flow path
And what will be the difference with ventury flow path & Straight flow path





RE: Ball valve flow rate & pressure drop
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The better suppliers' catalogs give CV values for their valves. CV varies with valve type and size.
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RE: Ball valve flow rate & pressure drop
It is more customary for a ball valve to have a "standard" port, which is typically one size reduced. There is a theoretically larger loss. In practice, the loss is about the same as one experiences fron an elbow.
FULL bore is really only required if something solid, such as a pig or an instrument probe, has to go through the ball.
RE: Ball valve flow rate & pressure drop
Hello Jim,
as usually good and to the point, but considering all variations of applications and types, not necssarily true for all.
If you have a look at the specialized application turbine inlet valves for hydroelectrical power plants (mecanically pure water) you will find following combination of requirements:
a) Fastest practically water speed adapted for the water distribution drum before the turbine. b) Least possible loss.
Result-> often selected double eccentric ball valves, full bore, with flow also round the ball in addition to full flow through the full opening.
Also for smaller ball valves for general/other application I believe (my personal view, no statistic) the trend in Europe to lean a bit more towards the use of full-bore in stead of reduced bore ball valves than in the US.
RE: Ball valve flow rate & pressure drop
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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: Ball valve flow rate & pressure drop
RE: Ball valve flow rate & pressure drop
I'll agree that in very small sizes (like 1 inch), it's not that big a deal. But in 12 inch valves, it is.
All things being equal, full port is more expensive to purchase, and the resulting flow loss of using standard ball is normally negligible considering other losses in the system. In such cases, you won't regain the difference in purchase price in energy savings.
bcd
RE: Ball valve flow rate & pressure drop
Just figuring a handwheel operated valve, using typical Cv for ball valves, a power cost of 0.8 ¢/kWh, more or less reasonable costs for valves (who knows what those are today), a 5% interest rate and what amounted to a 20% cost difference for 12" full vs reduced port, it seems extremely likely that, even if you vary those numbers quite a bit, full ports would pay for themselves at some point during the life of a typical facility. (See attached.)
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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: Ball valve flow rate & pressure drop
RE: Ball valve flow rate & pressure drop
What's the prices for the other sizes?
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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: Ball valve flow rate & pressure drop
**********************
"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: Ball valve flow rate & pressure drop
Almost invariably when I calculate for a regular port ball valve, the pressure loss is o.oo3 psi or in that range.
Sure: a full port valve may have 10% as much loss, but when the regular port valve's loss is too low to measure in the first place is is GOING to take a WHILE for any economic benefit to be realized by using a full-port valve..
RE: Ball valve flow rate & pressure drop
Granted payback does, at the very least, take a "while".
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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: Ball valve flow rate & pressure drop
Actually running numbers:
I selected a McCanna ball valve as representative.
3" standard port has a Cv of 397.
230 GPM gives a velocity of 10fps in a 3" SCH40 pipe.
the valve would have a DP of 0.59 psi in that installation.
Substituting an otherwise identical McCanna full port valve:
The Cv for a full-port 3" valve is is 763.
The DP is 0.16 psi at the same flow.
so the DP is 0.43 psi less with a full port valve in this application.
It's meaningful as long as there is not a control valve in the system running slightly more closed, absorbing the same energy that was liberated by opening the ball valve port a bit.
Meanwhile: the full-port valve costs a lot more, and the actuator torque goes up by some greater-than-1 exponent.
My point is: Most of the time a full-port valve is unjustified. Probably 95% or more. SOMETIMES, it matters. Digester Blow, Peelers, Pigged pipelines, Instrument tap valves, to name a few apps.