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Topic: Gas Illumination of a Leak  (Read 5306 times)

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Offline dl3mk3

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Gas Illumination of a Leak
« on: October 09, 2008, 03:01:48 PM »
I'm looking for a way to troubleshoot a leak in a gas-filled component which is small.  While there are devices that will detect a particular gas they do not show you where in a small system the gas is actually leaking from.  What i'm trying to find is a way to fill the system with a gas that can be visually seen, either with the unaided eye, or by some external illumination (UV?).  Inducing a smoke into the system would be hard but maybe the only solution I have.  If anyone has any information on a gas that fits this issue I'd appreciate it.

Offline macman104

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Re: Gas Illumination of a Leak
« Reply #1 on: October 09, 2008, 03:53:05 PM »
Depending on how big the leak is, one thing we used to do is take a sponge and soapy water, and apply it to the outside and look for bubbles.  This only works if the air flow from the leak is big enough, and if you don't have to apply it to a huge area.  But a thought.

Offline JGK

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Re: Gas Illumination of a Leak
« Reply #2 on: October 10, 2008, 10:49:33 AM »
Detergent solution as every gas chromatographer would tell you. If used correctly will spot even the smallest leak
Experience is something you don't get until just after you need it.

Offline wpenrose

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Re: Gas Illumination of a Leak
« Reply #3 on: October 10, 2008, 12:30:29 PM »
You'd be surprised how common this question is, and how few answers there are. Colored gases tend to be corrosive and poisonous, such as NO2, I2 and Br2 vapor. Sometimes you can use a dense gas such as SF6, shine a beam of light under the device being tested onto a white screen, and look for the density waves on the screen. Again, this takes a fairly big leak to get a response.

The traditional way of detecting gas leaks is to pick up the sound. Sometimes your ear is okay for this, but for the small scale you're talking about, ultrasonic methods are more sensitive. You might be able to do it on the cheap, with a crystal microphone with response into the 40 KHz, an amplifier, and an oscilloscope. Sometimes the sounds get up into the MHz and it gets very expensive.

Do you have to locate the leak or just determine that there is a leak? Sometimes a change in weight over time will do the latter, especially if you fill with a heavy gas such as SF6 or dimethyl ether.

Finally, you can build a little vacuum system with a fine tip and a flow rate of about 10-20 cc/min. Draw the gas over a carbon monoxide sensor. Fill the device with CO and use the sampling tip like a geiger counter to locate the leak. Building this would cost you $50 to $400 depending on the sensor and the vacuum system you use.

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Offline enahs

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Re: Gas Illumination of a Leak
« Reply #4 on: October 10, 2008, 02:41:04 PM »
Go to your local automotive parts store.
There are different brands, but you can get gases there designed for finding leaks. It is visible with a UV light. I forget all the details, but I used it once and it worked great.


Offline Enthalpy

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Re: Gas Illumination of a Leak
« Reply #5 on: March 02, 2012, 07:01:33 PM »
If no gas is efficient enough at absorbing UV, maybe you could accept a fine powder or mist in the gas?

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