[SBE] Ultrasonic Leak Detection

[Bill Whitt]

Ok I'm done -- there's a 4 on the end of that link that just will not copy
over ... I have to go 4x4 up 8 dollar mountain for a transmitter problem ...
so my head is up my you know what ...  

Bill Whitt


-----Original Message-----
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Bill
Whitt
Sent: Friday, May 16, 2008 10:51 AM
To: 'sbe member discussion mail list'
Subject: Re: [SBE] Ultrasonic Leak Detection

I really got to stop speed reading these things and read the whole message
....

And here's the link again since it didn't copy correctly --

http://www.nationalonlinetools.com/index.asp?PageAction=VIEWPROD&ProdID=2900
4

And yes I know things work great, a refrigeration friend uses these for
chiller issues all the time  ....

I get the DORK award for today ...

Bill Whitt


-----Original Message-----
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Bill
Whitt
Sent: Friday, May 16, 2008 10:42 AM
To: 'sbe member discussion mail list'
Subject: Re: [SBE] Ultrasonic Leak Detection


This would be a tough call for me if I had to make a decision between vacuum
or pressure leak detection. I know that vacuum leak detection is the most
accurate without a doubt ... and the most expensive to boot. The thing that
you have to realize is when you have leaks, and have a vacuum system that is
able to draw a substantially sized vacuum, the vacuum method is probably
going to pull the most junk into your waveguide ... vice pressurizing the
waveguide keeping junk out. Not only that ... if the o-rings in the flanges
are failed ... its going to pull them into the system. Some joints are
designed to seal with pressure ... if you draw "Backwards" ... you'll end up
with joints suddenly leaking all over the place. I would continue to
pressurize the system doing exactly what your doing if I had no money in the
budget ... 

BUT, if you have a couple hundred bucks ... say around $300.00 ... you could
get something I know works really well in refrigeration.

It's called a ultrasonic leak detector. You can continue to keep the
integrity of the system pressurized with this device. Here's a link to one
for an example -

http://www.nationalonlinetools.com/index.asp?PageAction=VIEWPROD&ProdID=2900
4

There's more expensive models with more bells and whistles, but basically it
"listens" on an extremely sensitive level for leaks around your joints and
flanges on a pressurized system. A Nitrogen pressurized system works really
works the best since Nitrogen is molecularly smaller than air ... those
little molecules can creep by the smallest leaks and make a ton of noise.
This would be great to follow up on new installs with. 

What you would do is pressurize the system with Nitrogen at your
safest/highest pressure ... wait a couple hours ... then start looking with
one of these devices until you found all the leaks. If you think you have
HUGE leaks ... or your running out of Nitrogen in your bottle ... then use
air until all the big leaks are found. Once the "listener" has found no
leaks with Air ... switch to Nitrogen to see if you can find any small ones.

This is my 2 cents worth ... you could just keep going until you have DAWN
hands ...:-).

Bill Whitt


-----Original Message-----
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Chris
Spacone
Sent: Friday, May 16, 2008 7:17 AM
To: curt at spam-o-matic.net; 'sbe member discussion mail list'
Subject: Re: [SBE] Ultrasonic Leak Detection

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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