pipe flow calc 1

[SHOchris]

i have a leaking pipe, all i know about it is size and pressure...i am trying to find the Qout of the leak...
so how do i relate the water pressure to a velocity?

"Don't worry about the world coming to an end today. It's already tomorrow in Australia."
---Charles Schulz
"Beer is living proof that God loves us and wants us to be happy."
---Benjamin Franklin

 

[GoldDredger]

I think you have too many unknowns to determine Q out from leak only based on size and pressure in the pipe. Do you have access to the leak? (by timing how long it takes to fill a bucket?

Q= Velocity x area of cross section

 

[SHOchris]

right, that would be ideal, but i am not even near it...i told that idea to the guy over the phone and he said that is not possible with the way it is leaking...

"Don't worry about the world coming to an end today. It's already tomorrow in Australia."
---Charles Schulz
"Beer is living proof that God loves us and wants us to be happy."
---Benjamin Franklin

 

[coloeng]

Is the pipe downstream of a meter where you could isolate every use except the leak? Do you have to know the amount before you fix the leak, or can you determine how much water you lost after you fix the leak and know how big of a hole it has? What other information do you have about the leak?

 

[dicksewerrat]

Why would knowing how much is leaking be important? Unless it is oil, gasoline, etc. You still have to fix the pipe.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[cvg]

visually estimate the flow using the GHU - see the following post thread193-204542

 

[MiketheEngineer]

Can you measure how much is going in and how much is comng out?? Or even the flow depth at start and end??

 

[SHOchris]

Sorry for the long time to reply guys, i was out in the field the past couple days.
Basically, I just had to go out and watch the dang thing and record two water levels, and then find the change in volume vs. the time it took to raise the level... I know that it comes out low because of water penetration into the soil... but its probably within 15% cause by the time i got out there most of the soil was saturated.

there were no meters, no valves....it turned out that back in the day, whoever installed this valve used the wrong one which is what actually failed.
I really dont know why we needed to know it dick, i just know my boss told me to find out... maybe to charge them for the water they lost?


"Don't worry about the world coming to an end today. It's already tomorrow in Australia."
---Charles Schulz
"Beer is living proof that God loves us and wants us to be happy."
---Benjamin Franklin

 

[chicopee]

Here is a way to find out the quantity of water leaking. But first the water must shoot out of the pipe horizontally in a stream flow--not spray form.
First determine area of hole.
Secondly measure the vertical height between the hole and the ground.
Thirdly, measure the horizontal distance from the hole in the pipe to the center of the water pattern on the ground. This location should be preferably at the same ground elevation at which you measured the vertical height.
Fouthly, applying the trajectory equations that you had in physics or calculus, calculate the horizontal velocity of the water coming out of the hole.
Lastly, apply the well known equation Q=C x velocityx hole area; C is a coefficient and if you use .6, your Q will be in the ball park.
Note the water can also shoot out of the pipe at any angle except vertically and that angle has to be measured; also you can have differences in ground elevation but these two situations would complicate your trajectory equations.

 

[RWF7437]

Or.............. put a bucket under the flow stream and time how long it takes to fill.

 

[chicopee]

Yep! that should work too as long as there is no overspray and no evaporation.