[SBE] Ultrasonic Leak Detection

[Chris Spacone]

Cowboy,

I used a rig similar to this when I worked as an engineering technician at a
medical device startup. We would attach the leak detector to the UUT (unit
under test) and then pull a vacuum on it (pretty hard as I recall 10 -12
torr). The system incorporated what the manufacturer called a 'cee tube'
which was a mass spectrometer assembly shaped like a shallow 'C'. This tube
was in the vacuum path inside the machine and was tuned to react to helium.
Once calibrated (why using a calibrated leak source of course!) the operator
would spray helium on the UUT (joints, flanges & welds). If there was a leak
the machine would make wailing noises proportional to the size of the leak
and simultaneously give a meter reading that showed the size.

I wasn't aware that there was an opposite method that employed
pressurization of the UUT. Do you have any further information? Anybody?

73,
Chris

-----Original Message-----
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Cowboy
Sent: Friday, May 16, 2008 7:08 AM
To: sbe member discussion mail list
Subject: Re: [SBE] Ultrasonic Leak Detection

On Friday 16 May 2008 09:48 am, Chris Spacone wrote:


>  I would like to avoid pouring lots of soapy water all over waveguide

>  flanges, couplings and the rest of the system to find a nagging leak or

>  leaks.


 That is the cheapest and most common way.
 Smoke works well in still air.


>  Here is the question(s): Anybody have any experience with ultrasonic leak

>  detectors? If so are they a vast improvement over shotgunning the

problem?

>  Any recommendations for a source / manufacturer? Perils / pitfalls?


 I can see a problem in any noisy environment. I'm sure all of us would be
 interested in the result if you go that way.

 Personally, a sniffer would be a better shot.
 This would require that you can introduce some inert gas into the system
 that won't be a later problem if not purged, but those gas sniffers
 are incredibly sensitive, especially for any non-atmospheric gas.
 Get within two feet of a leak, you'll find it.
 Check with a local hospital and see if you can't borrow something.

-- 
Cowboy

http://cowboys.homeip.net

"The medium is the massage."
-- Crazy Nigel

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