Leak detection based on pressure

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Discussion Overview

The discussion revolves around leak detection in a pipe network consisting of two pipes with different diameters (100mm and 150mm). Participants explore the pressure dynamics within the pipeline under various conditions, including scenarios with and without leaks, and the implications of flow rates on pressure calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • One participant questions whether the pressure is uniform throughout the pipeline when filled with water and without flow, to which another participant confirms that it is, assuming horizontal pipes.
  • Participants discuss the application of Bernoulli's principle to calculate pressure differences in the presence of a leak, noting that the specific setup must be considered.
  • A participant proposes a method to determine leakage rates by calculating initial velocities and comparing inlet and outlet flow rates, seeking validation of their approach.
  • Another participant suggests that if there is no flow apart from the supply and leaks, the pressure remains the same at the transition between the two pipe diameters.
  • There is a discussion about closing certain valves to isolate sections of the pipe network to assess leakage contributions from different leaks.

Areas of Agreement / Disagreement

Participants express various viewpoints on the pressure dynamics and methods for calculating leakage, indicating that multiple competing views remain. The discussion does not reach a consensus on the best approach for leak detection or pressure calculations.

Contextual Notes

Participants acknowledge the dependence on specific setups and conditions, such as whether the pipes are horizontal and the nature of the flow measurements, which may affect the calculations and conclusions drawn.

darren000
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Could someone please help me with this??

I am working on a problem with 2 pipes, one 100mm and one 150mm in diameter. The shape of the pipeline is a square. Majority is the 100mm pipe and the other is 150mm pipe.

1.If entire pipeline is filled with water, no leak and no supply, is pressure the same through out the pipeline?

2. If no supply, and there is a leak point on the 100mm pipe at a rate of 1 L/min. what formula should I use to calculate the pressure difference?
 
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1.If entire pipeline is filled with water, no leak and no supply, is pressure the same through out the pipeline?
Without flow and if the pipes are horizontal (or without gravity), yes.

2. If no supply, and there is a leak point on the 100mm pipe at a rate of 1 L/min. what formula should I use to calculate the pressure difference?
Depends on the setup. Bernoulli's principle might be useful, but you really have to take the setup into account.
 
Thanks for replying mfb,

Please help me little further. I have attached a drawing of this problem.

As you can see. My task is to determine if there are any leak in this pipe network.(sorry, 100mm PVC is on the left side of A until 50mm Blow-Off, rest is 150mm)

1.If I close valve C and A, can I calculate the leaking rate of the leak 3 and leak 1 using following steps? Since I have supply flow rate and pressure, I can calculate initial velocity, then I can use the pressure on the port to calculate the velocity at the outlet near pressure monitoring port. With velocity and pressure at the port, I can calculate the output flow rate.
I'm stuck here. if I minus outlet flow rate from inlet. Does that = to the rate of leaking??

2.Any idea how I can determine leakage on the left side of valve A? (Shut valve B and see if outlet flow is same as what we found before considering leak 3 and leak 1. If flow rate is the same, then there is no leaking on the left side of valve A). Is my thought on the right track?

Thank You very much for helping.

Very Appreciate
 

Attachments

In setup 1, is there any flow apart from Supply->leaks1+3? If not, there is no flow at the 100mm<->150mm-transition and pressure is the same at both sides. If your flow meter measures flow itself, that should be the same as the flow through the leaks, right? If it just measures velocity, you can use the measured pressure to calculate flow.

2) Closing B and opening A C D should work - if you know the flow through leak 1+3 (as determined in 1), you can calculate the total leakage again and find the contributions from the other leaks. If flow is significant, you might have to consider pressure differences in the 100mm<->150mm-transitions or in the pipes itself (again, depends on the setup).
 

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