Hello,
I'm dealing with a problem and I wonder if anybody can provide me with some insight. I plan to have a 20-meter closed pipe filled with compressed air or maybe CO2. The pipe may have some small leak. I want to put a pressure sensor on one end of the pipe, so as to take periodic readings and monitor for abrupt changes due to punctures, breaches, etc. My problem consists in figuring how to distinguish the change in pressure due to the normal leak and normal temperature variation from the change that would happen if the pipe suffers a significant puncture. I suppose that if I wait long enough the pressure will drop to 1 atm, but I would like to know if that would be quick enough for my purposes, so that's why I'm looking to have a theoretical model of this system. I could also monitor the delta pressure, but again I would need to know how the pressure should behave in the normal situation. My background is computer science; I can grasp of physical concepts but my calculus has rusted a lot. Thanks in advance.
Leo
Punctured pipe decompression
Re: Punctured pipe decompression
If you have discharge from pipe and a possible discharge from puncture I think there is no chance with pressure sensors to find out if something is going out from the pipe due to puncture.
Very precise flow meter on the start and on the end of pipe can indicate that you have puncture, but it depends on the precision of flow meter.
In regular practice it is common to use water with soap and to overflow the pipe and look for bubbles.
The other way is to inject fluid that has some characteristic odor so you can smell along the way and sense if the pipe is leaking like it is common in gas lines and LPG.
Very precise flow meter on the start and on the end of pipe can indicate that you have puncture, but it depends on the precision of flow meter.
In regular practice it is common to use water with soap and to overflow the pipe and look for bubbles.
The other way is to inject fluid that has some characteristic odor so you can smell along the way and sense if the pipe is leaking like it is common in gas lines and LPG.
Pipe flow calculations - since 2000
Re: Punctured pipe decompression
Just having an idea of how pressure evolves over time would be useful for me. I'm not looking for an exact solution. Supposing there's no other leak and supposing external temperature remains constant, what would the pressure function (with respect of time) look like when there's a puncture and it's measured at the pipe's end? Would it decrease exponentially as it tends to 1 atm? Or geometrically, or...?
Edit: Let me explain. This is supposed to work as an alarm system to detect pipe breach, that's why I don't need an exact solution. The pipe is mostly vertical (with curves, probably) and must be filled with a gas. I can only check for pressure in one end (not on both). Having a pipe without leaks is possible, but I first included them to account for defective valves, etc. Let's suppose there's no leak, and I'll build a margin into the controlling algorithm afterwards. Thanks.
Edit: Let me explain. This is supposed to work as an alarm system to detect pipe breach, that's why I don't need an exact solution. The pipe is mostly vertical (with curves, probably) and must be filled with a gas. I can only check for pressure in one end (not on both). Having a pipe without leaks is possible, but I first included them to account for defective valves, etc. Let's suppose there's no leak, and I'll build a margin into the controlling algorithm afterwards. Thanks.
Re: Punctured pipe decompression
If you have no leak just the puncture than you can check it with gauge. Flow through a hole depends on pressure difference and as it changes over time, also flow will change. The curve should be like exponential.
Pipe flow calculations - since 2000