Calculating water loss 1

[ballette]

Hi
I need some help with an issue I have on site.

A pipe 100 m in length 40mm radius is pumped with water and put under 4bar of pressure for a pressure test, to test the integrity of installation. After returning to the test 10hrs later, the pressure fell had fallen to 3.1bar. The test failed due to pipe leaking or a valve letting by.

So, there was a fixed volume of water in the pipe at 3.5bar at beginning of the test. I need to calculate how much water was left in the pipe at 3.1 bar or how much water was lost.

Hope this is clear.

Can someone direct me to an equation that could help.

Thanks
Ballette

 

[BigInch]

Its here,

http://www.slc.ca.gov/Division_Pages/MFD/SLPT/Revised_SLPT_Guidelines_12-03-03.pdf

**********************
"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/

 

[racookpe1978]

"A pipe 100 m in length 40mm radius is pumped with water and put under 4bar of pressure for a pressure test, to test the integrity of installation."

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You need to clarify your terms to more accurately calculate the (original) volume of water trapped in the pipe.

"Exactly" 400 meters long?

40 mm "radius" is meaningless - no one (outside of a textbook problem (hint) defines ANY pipe by a "radius" - So determine if this is an "internal diameter" or an external diameter pipe - and, if external, what schedule of pipe (how thick are the walls)?

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What is the "real world" volume of the fittings or "valves" or cross-connected pipes going to the supposed valves that are leaking? If there are only two valves (which is not a very frequent real world solution because then you'd have unrelieved pressure rises from temperature changes between the two valves), then look in the end of the pipe where the two valves are and figure out which one is leaking. 8<)

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Have you looked at temperature changes for the test duration?

 

[BigInch]

racook,

Hey man take a break.

You don't calculate the volume of water, its metered going into the pipe, so you don't need to calculate the volume in valves, pipe, don't need to know the OD or ID, volume of the fittings, nobody said anything about cross connected pipes and only mentioned "a" valve, as in 1, and maybe even the temperature didn't change. Nothing mentioned about it one way or another.

If you want to give him trouble, what about the fact that what he shouldn't have been doing was testing against "a" closed valve. Maybe that did fail the test.

Anyway, I think he already got the answer he needed. Let it go. Get some sleep.

**********************
"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/

 

[racookpe1978]

No, I disagree - though this certainly might be a field test run. I just disagree with the situation as described: The hydro tests I've run just aren't ever (in thirty years) described that way, nor run that way.

Delta volume proportional to delta temp? Yes.
Delta volume proportional to delta pressure? Yes.
Delta pressure proportional to both? Yes.

Calculate volume of water lost? You need to know - exactly - what volume you started with: and "pumping it up" isn't close enough. A branch run is not only the probable place of lost fluid - but a source of the second, thrid, fourth isolation valve or test blank, or leaking tank, or vented tank through a leaking vent valve... etc.

And I've never participated in any test where anybody cared about "volume" of water lost - pressure loss was/is the critieria. WHERE the loss went to was critical. Not "how much was lost?"

But I digress - you're right - none of my concerns "might" be a factor. I don't know his mind, nor his circumstances, or the circumstances of the test. But if he doesn't look at the "other factors" that be farkling his test, he won't fix the farkle factors, and his answer won't be right.

8<)

 

[BigInch]

Sleep. Sleep. Sleep.

**********************
"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/