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How to calculate the amount of flow on a valve that is passing

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Vivaldi SMITH

Vivaldi SMITH

Student
Nov 12, 2020
20
US
I am trying to calculate how much flow is going through a valve that i am suspecting is passing.
What formula can i use, please i need this urgent help. Thank you
 
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Vivaldi SMITH,

If you are using a commercial valve, the manufacturer will have specifications on flow rate versus pressure head. If there is a liquid, there are always graduated cylinders and watches.

--
JHG
 
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Are you asking about leakage past a closed valve?

--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
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You usually have to measure that.
Most manufacturers don't admit their valves leak unless they have been damaged by you.

 
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Not trying to be snarky, but... a bucket? Seriously, just close a valve and see what seeps out over some period of time. I feel like we're trying to turn a middle school math question into a NASA science project. There's no formula other than rate over time. You can't calculate rate unless you have pressure (which you may have), area of unsealed gate (which you likely don't have), type of flow across gate (laminar vs non), etc. Grab a bucket and be done with it.

Dan - Owner
Footwell%20Animation%20Tiny.gif
 
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Shape of the leaking area, fluid type, viscosity, density, molecule size, sharp edge, or rounded edge, materials, pressures all have influence. You can spend $100K studying that problem and still never get it right.

 
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How many brand new shower valves leak? If the answer is "negligible numbers," then there is no formula, PERIOD. Leaks are usually too small to measured by flow sensors, so a bucket is pretty much it.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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Replying to MacGyverS2000 , excellent approach except whoever is going to get a bucket of gas ( In gas state) will probably get a Nobel price in Material Science.
 
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The plot thickens (and the specific gravity drops).
Do you have any idea how frustrating it is to have every valid suggestion shut down by some undisclosed information?
If you really want help, start with a complete description of your system.
If you don't have time to do that, then don't waste our time.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
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Replying to snark with snark... no one said the bucket had to be open-ended. A gas capture bottle that remains at sufficiently low pressure compared to the system as a whole would achieve the same goal.

But if we really want to beat the snark... propane (among numerous other gases) is heavier than ambient air (50% heavier, in fact), which means one can, in actual fact, get a "bucket of gas". Of course, none of this was specified in the original postulation, so we're solving problems piecemeal.

Dan - Owner
Footwell%20Animation%20Tiny.gif
 
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Despite the condition; "( In gas state)" this exchange brought back memories of the high school chemistry teacher who was telling us that SO[sup]2[/sup] could be liquified.
I asked if she would like to see some liquid SO[sup]2[/sup].
She said that that would be interesting.
The next day, I showed her an open test tube half filled with very cold SO[sup]2[/sup].
Then she leaned over and looked down into the test tube and got a nose full of off gassing SO[sup]2[/sup].


--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
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waross - why did you have a very cold test tube of SO2?
 
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To show the chemistry teacher an actual example of liquid SO[sup]2[/sup]
I had been woking on refrigerator repair. In those days SO[sup]2[/sup] was available in one pound Cherge-a-cans.
I happened to have a can of SO[sup]2[/sup]
I cooled it in the freezer overnight.
At school the next day,I used a Tap-a-can valve to pour liquid SO[sup]2[/sup] into a test tube.
It still wasn't cold enough and so it boiled. The boiling, self cooled it to about minus 20F and it stopped boiling.
It was slowly evaporating and out-gassing.
I didn't intend for the teacher to breath it. Unforeseen consequences.
A good whiff of SO[sup]2[/sup] is almost as bad as a blow to the nose.
Nasty stuff.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
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Extra work for extra credit? Not that day. grin

--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
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I guessed the first line of that answer. The rest, huh. The closest I've gotten to fun sulfur compounds was SF6.

The sniff test - an opportunity to once again plug "Things I Won't Work With" by Derek Lowe. I'm surprised any chemistry teacher had not learned the "wave it gently to you" rather than "jam it into my snoot and snort it" technique.
 
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