Energy saving - Repairing air leaks on compressed air lines
What is the results of air leaks on compressed air lines?
Air leaks normally occur at the joints, flange connections, elbows, valves, filters, hoses, etc. as a result of thermal cycling and vibration.
How to detect air leaks?
where: 1 < n < 1.4 (isentropic) and 0.7 < hcomp < 0.9
From knowledge of fluid dynamics, we know that when line pressure P2 > 2 atm, the velocity of air at the leak site is equal to the local speed of sound.
Thus, the mass flow rate of air through a leak can be expressed as,
where:
k = specific heat ratio = 1.4 for air
Cdischarge = 0.65 (approx.)
From the above equations, you can calculate yourself to see how the energy is wasted through air leaks if the leak site has 3 mm diameter and the line pressure Pline is 5 bar. You will see that a lot of money is wasted!!
Read more details how to save the energy
- An air compressor works harder
- An air compressor works longer
The above undesireable results make the compressor consumes more energy.
Eventhough air leaks is unavoidable, but with good house-keeping factory, the level of air leaks of 10% is acceptable. Most of the factories have air leaks far beyond that what mentioned.Air leaks normally occur at the joints, flange connections, elbows, valves, filters, hoses, etc. as a result of thermal cycling and vibration.
How to detect air leaks?
- Listen for hissing sound -- in some factories, even when in production process, we can still hear this sound if the leakage rate is high
- Apply soap water at the location where the air leaks may present
- Using an acoustic leak detector
- Pressure drop test
Mechanical energy wasted caused by air leaks
The following equation expresses the actual mechanical energy wasted due to air leaks
where: 1 < n < 1.4 (isentropic) and 0.7 < hcomp < 0.9
From knowledge of fluid dynamics, we know that when line pressure P2 > 2 atm, the velocity of air at the leak site is equal to the local speed of sound.
Thus, the mass flow rate of air through a leak can be expressed as,
where:
k = specific heat ratio = 1.4 for air
Cdischarge = 0.65 (approx.)
From the above equations, you can calculate yourself to see how the energy is wasted through air leaks if the leak site has 3 mm diameter and the line pressure Pline is 5 bar. You will see that a lot of money is wasted!!
Read more details how to save the energy
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