[SBE] Ultrasonic Leak Detection

[Chris Spacone]

Ron,

We had a compressor on it and it was feeding a manifold with a desiccant
canister in line. I agree, humping around 200 size bottles of N2 might
eventually give me Popeye arms but I'd rather not find out.

Deal is the boss is convinced that we can/should/will find the leak so that
we can continue to use N2 instead of a compressor. I really can't argue with
his reasoning; the leak really shouldn't be there so find and fix it I
shall! 

Chris



-----Original Message-----
From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Ron
Bailer
Sent: Friday, May 16, 2008 2:14 PM
To: 'sbe member discussion mail list'
Subject: Re: [SBE] Ultrasonic Leak Detection

Another option would be a small de-hydrator.  Makes current, and future,
leaks a moot point.  Or if not moot, at least time shifts them to when you
have time to deal with them (yah...right.)  I really liked my desiccant
based Andrews unit, and it wasn't a whole lot more than an ultrasonic leak
detector.
And trust me a can of silica gel is a LOT easier to carry than a tank of dry
N2.  Just don't use the oven to dry it when the wife is around.

Ron  




Bailer Applied Engineering
       www.bailer.com

Ron at Bailer.com
Voice:  (970) 416-6483


> -----Original Message-----

> From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of Chris

> Spacone

> Sent: Friday, May 16, 2008 2:48 PM

> To: 'sbe member discussion mail list'

> Subject: Re: [SBE] Ultrasonic Leak Detection

> 

> No worries Bill. I hadn't given any real thought to pulling a vacuum on

> the

> waveguide, just drawing a parallel with another leak detection method that

> I

> used in another life.

> 

> It is good to know that the ultrasonic method isn't without merit. Cowboy

> brings up some good points but I was thinking the background noise issue

> shouldn't be an insurmountable hurdle. As I understand the process the

> ultrasonic noise made by the leak is mixed (heterodyned is the literature

> term used by some vendors. Right up our alley, eh?) and downconverted to

> something we can hear.

> 

> Right now the system is blowing nitrogen into the atmosphere so I'm hoping

> that it at least is keeping the critters and humidity out. But this cannot

> continue long as swapping out N2 cylinders will get expensive and annoying

> (in various portions of each).

> 

> 73,

> Chris

> 

> 

> -----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=29

> 00

> 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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