How to Calculate: Rate of Pressure Loss Through a Pinhole Leak 1

[spd60]

Hi,

Hoping that someone can give me some guidance on the following:

How would I calculate the theoretical pressure loss from a pressure vessel that would occur over a 24hour period through a pinhole leak based on the following starting conditions:

Starting pressure: 700psi
Medium under pressure: Air

Basically, I'd like to calcualte the theoretical pressure loss that would occur over 24hours if there was a pinhole leak through the wall of the pressure vessel that was pressurized with air at 700psi.

Thanks

 

[kwaliteitshenk]

spd60,

Depends on the volume of the pressure vessel.

 

[israelkk]

Depends on the pin hole diameter.

I think you should be more clear what do you really want. If you know how much pressure drop is allowed in 24 hours you can calculate/estimate the equivalent "pin hole" diamter.

 

[zdas04]

How about a third opinion? If the hole is small enough and the vessel wall is big enough then the leak will act like a pipe. If the hole is "big" relative to the wall thickness then it acts like a choke.

I think the breakover is something like L/D ratio around 10 but I can't find the reference right now. This means that if the hole is 0.1 mm and the wall is over 1 mm then you have to consider pressure drop within the hole.

In either case, flow rate is a function of hole diameter and vessel pressure. Pressure drop is a function of flow rate and vessel size.

There is a lot of information required for a seemingly simple question.

David

Remember: The definition of "easy" is "someone else has to do it"

 

[fortmceng]

spd60,

check this website link. Hope this helps to some extent.

http://www.lacotech.com/products/997300658_leaktechref.pdf

 

[spd60]

Thanks for the replies.

I did some more googling and found links to an article/paper that contains two methods to solve the problem and seems to do the trick.

http://www.air-dispersion.com/feature2.html

A little bit of excel work and voila.

Cheers