Diesel Leak rate through a buried pipe 1

[Atwerp]

I need to calculate the rate diesel would leak out of a 2" steel pipe buried 3' below grade. The hole was approx. 1/4" diameter and the pipe is under 20 psi pressure. I know the soil type will probably affect the rate. If it is easier, can I find the maximum leak rate assuming the pipe were not buried and then deal with how the pipe burial would affect the rate?

Thanks

 

[kyong]

Antwerp, rho is density.

BigInch, your vena contracta factor 0.62 is more specific than my 10~50% friction loss.

One thing I reconsider is that resitence by liquid can be bigger than I originally thought. If ratio of compactness of the soil to leakage flow rate is high, it can be prettry significant, because liquid need to penetrate the soil.

 

[BigInch]

Soil in a trench is no factor at all. Nobody in the petroleum pipeline business considers any such doil resistance. Trenches are full of sufficient voids.

Besides, whenever fluid is stopped in its path leading back to the hole, pipeline pressure catches up to it. Full pressure can be transmitted through the tinest hole provided that there is (effectively) no flow. Your equation predicts the same effect. What is pressure DROP when V = 0?

http://virtualpipeline.spaces.msn.com

 

[CarlB]

There are engineering disciplines that do not ignore for conservatism or simplification the fact there is resistance to flow in porous media. Think of fluid flow in soil as occurring in many pipes of very small diameter. There are many earthen dams that retain water without blowing out thanks to this phenomenum.

 

[BigInch]

As long as there is some flow, there is a pressure drop that can be calculated, so full hydrostatic pressure behind the dam will not be seen at that point where the pressure is being calculated. Without flow, pressure drop = 0.

Just remember the Donald Duck cartoon. The dam doesn't blow, until he puts his finger in the little hole.

http://virtualpipeline.spaces.msn.com