Air Leak Checks in Low Pressure System

K

Thread Starter

kmnskiran

In IPB (Isolated Pressurization bus Duct) PLC Control panel consists of relays, polyurethane and push in fittings. Due to very low air leaks at panel tubing, High-Low Pressure switches gives solenoid coils on-off commands frequently. so chattering of SOV'S increases.

It is difficult to sense the air leaks. My question is, How to check & resolve these small air leaks?
 
Hi,

It's difficult to propose a course of action when you haven't told us what you've done to check for leaks--or any other particulars about the installation/application.

What does the equipment manufacturer suggest for checking for leaks?

A simple but effective method for checking for leaks of any pressurized system is to use a solution of soap and water sprayed on joints and suspected leaks.

How long has this equipment been in use?

Have you checked the non-return valve ("check valve") between the pressure source and the equipment--which may be internal to the pressure regulator?

Has anyone reviewed the P&IDs to analyze various components (like the pressure regulator)?

Pressure switches have even been found to have internal leaks in diaphragms and/or seals.

Troubleshooting is often a process of elimination until the source(s) are all identified. Often, there is more than one leak. And, often the manufacturer publishes allowable "leakage rates" that are useful in determining if a system is restored to a good condition. Many times the presumption is there should be zero leakage, when in fact that's not possible given the construction and/or components used. Even the best vehicle tires need air added to them from time to time; no material is completely leak-proof (except beer cans).

Please write back to let us know how you fare in finding the leak(s). And, please tell us what has been tried in the effort to find the leak(s), and if there are any restrictions on the use of liquid leak detection methods (like soapy water).
 
G

Gerald_Beaudoin

Any air leaks generally emit sound in the ultrasonic range. An ultrasonic detector work very well for locating the problem.
 
Hi
Thanks for reply

There is a limitation of using soap water in that particular location, since many electronic and electrical components exists in the system.
Pls suggest us alternative method other than expensive ultrasonic method.
 
Ultrasonic detection equipment can be quite inexpensive....a few hundred dollars can buy equipment suitable for detecting small air leaks. Calculate the cost of lost air and compare that to the price of diagnostic equipment.

> There is a limitation of using soap water in that particular location, since
> many electronic and electrical components exists in the system.

> Pls suggest us alternative method other than expensive ultrasonic method.
 
C

Curt Wuollet

Believe it or not, I've seen someone take an old "t-shirt" type shopping bag and wrap it around each joint and see if the plastic inflates. It worked, too.

That was in a location too hellishly noisy with too much air movement for the more conventional methods. A fluffy (downy) feather can show air movement undetectable by feel, as can dragging a length of teflon pipe sealing tape across the joint. It clings by virtue of triboelectric charging, but will deflect with a very small leak. A diaphragm stethoscope can be a "poor mans" ultrasonic device, not at all ultrasonic, but sensitive to gas hitting the diaphragm. And speaking of stethoscopes, the old reliable cheapy mechanics stethoscope can sometimes detect the vibration. A similar method is to simply unplug end of the stethoscope Y tube from the "chest piece" and probe around with the open end of the tubing. Baby powder can be used with soft brush along a seam looking for places where it's blown away. Soapsuds is just one of the easier ways and works for very small leaks. A little imagination goes a long way.

Regards
cww
 
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