I have just heard from a friend that Helium is used for detecting the smallest leaks in a system.
The system evacuates and filled with Helium up to 15psi and the leak is detected with th regular electronic leak detector.
Any comments?
Chemi
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I have just heard from a friend that Helium is used for detecting the smallest leaks in a system.
The system evacuates and filled with Helium up to 15psi and the leak is detected with th regular electronic leak detector.
Any comments?
Chemi
Hi Chemi,
Are you sure that it is an electronic leak detector and not an ultrasonic leak detector? :confused:
Helium was used more by manufacturers previously because the detector was hugely expensive, however I believe cheaper detectors have become available in the last few years.
Helium doesn't detect smaller holes, however it does show leaks more quickly than standard leak tests, and that's why it was advantageous to manufacturers of coils who could process their production more cost effectively
Hi donhoban.
Isn't the molecule of Helium smaller, allow the gas to come out in smaller holes then refrigerants?
Peter, I haven't a clue but ultrasonic detector is very uncommon with fridgy's.
Chemi
As I understand it, bearing in mind, I'm an engineer,not a phyisicist or chemist - molecular size of helium is about 10-10m or 0.0000000001 metersQuote:
Originally Posted by chemi-cool
Say we assume the leak is 1/1000 of a mm across - we'd still potentially fit 1000 molecules of helium across the gap at any one time!
So really, unless we start dealing with monster molecules, I don't think the relative size difference between helium and refrigerant is important.
I could of course be wrong :)
Hi donhoban.
From what I've heard, this is why Helium is being used.
I dont see any other reason.
Chemi :)
Helium has been used for many years in certain production methods where a high degree of system tightness is demanded. Typically it could be used for measuring the porosity of high end spec castings.
The ?detector? as such is a mass spectrometer. Despite its very high level of efficiency it is also potentially the most expensive because of the equipment needed.
I saw it used by Carrier many years ago in Syracuse where they were testing Absorption system unishells. The whole machine would be wrapped in a plastic ?tent? and a measured amount of helium admitted to it. A vacuum pump would then draw a vacuum on the inside of the system and the exhaust of the pump would be directed through a mass spectrometer.
Not a technique for your average site??.
________
marijuana vaporizers
Hi :)
we use nitrogen with 10% Helium for strenght/leak testing HFC refrigeration systems. This in my experience is the only way to ensure that an HFC plant is gas tight.
Add the nitrogen, add the helium, get the soapy water out and watch the leaks appear. :o
Kind Regards. Andy.
Thanks Andy.
Thats the kind of answer I was looking for.
Chemi :)
I'm sorry I failed you Chemi :rolleyes:Quote:
Originally Posted by chemi-cool
You certainly didn't!Quote:
I'm sorry I failed you Chemi
The whole thing came up when I had a discussion with a local manufacturer about better ways to locate leaks in systems in new units.
He mentioned the Helium test as Argus described and I was sure I will find more practical answers here.
Andy is a very practical person and I like his answers.
Chemi
No worries, I'm only yanking your chain :)
I must admit though as far as site installs, I'm with Andy, soapy water is the only way!
You know, as all as those electronic gadgets are concern, I think I'm one of these who always use the soapy water.
Never let me down.
Chemi
Hi :)
Yes i agree,to clarify leaks good old soapy water ;)
For the last 4 years ive been using a electronic javac Tekmate they can really aid leak detection,Ive found alot of leaks with this unit .Mostly in large supermarkets ;)
The sensitivity of the leak detector can sometimes be misleading :eek: ,but allows leak detection of most refrigerants including HFCs :)
Best regards Mark :)
Leak check a Copeland: they pull each compressor in a vacuum.
Then, the compressor goes in a sort of small iron chamber (+/- 3 ft high and 2 ft diameter) and they add a light helium pressure in that chamber.
The vacuum hoses are still connected to the running vacuum pump. At the outlet of the vacuum pump, they have a very sensitive mass spectrometer which can detect the smallest amount of helium.
They said there that they use helium because it can escape the easiest of all gasses through very small leaks and it's with the proper electronics easy and accurate detectable.
Each compressor has always leaks through the gaskets (the gaskets are made of some sort of paper and has a capillarity), you could see on the computer of the mass spectrometer a rise in the graph as soon they added helium but then the graph flattened - but they know for each compressor the 'standard leakage'
As soon as a compressor goes beyond this 'standard leak' it goes out the line to search for the leak. This test last only some minutes.
Then it goes to the final drying: vacuum for a longer time with a DC current through the windings to heat up the internal of the compressor.
Same technique for vacuum chambers (+/- 2 m diameter) where they evaporate aluminum on a foil to make capacitors.
To test the seal/gasket, they pull a the vacuum chamber in vacuum and at the outlet of the vacuum pump a mass spectrometer.
They then go round the sealing with a flexible which is exhausting a very small amount of helium.
We did once the same test there in that factory: mass spectrometer at the outlet of our standard pump which we had installed with long hoses 15 m further away, sprayed with the helium and in no time we had the leak. We also saw 'leaks' around the gaskets.
I have an ultrasonic but it's only usable to search for leaks in gaskets around the doors.Quote:
Originally Posted by chemi-cool
You must almost hear and know where the ***** leak is to find it with an ultrasonic.
Surely if we start using Helium for leak detection we are going to all start talking like Joe Pasquale :eek: :D
Regards
Raymond
True, but I recommend it as a very valuable tool under some conditions. I finally broke down and bought one a few years ago when a leak was driving me crazy. They had come down to about $200. Mine uses earphones and supplies a hiss in the hearing range proportional to what the detector is receiving, with a sensitivity adjustment.Quote:
Originally Posted by chemi-cool
They are excellent when a system is out of gas, since that usually means a large leak which overwhelms most halide detectors. Of course the oil often shows such a leak, or you can find it quickly by pressurizing with nitrogen and listening for the hiss, but when this fails, the best feature of the ultrasonic detector is that you can use it directionally.
You need to pressurize with nitrogen if the system is empty and shutdown fans and adjacent equipment to eliminate background ultrasonics but then you can home in on the source very quickly, in many cases. With a thumb on the sensitivity adjustment, you track the noise right to the source. Last time, I found a leak in the interior of an evaporator coil in minutes, which was losing about 2 ounces per day. (Pressurized to 100 psi first.)
For very small leaks and on rooftops where there is too much background ultrasonic noise (wind, traffic) it is not effective.
Rog
Never heard about this helium technic , but from 2 days i watched a show on discovery about Boing the aircraft manufacturer and they use ammonia gaz to test the (wings) fuel tanks for leak , they fill the wing with ammonia gaz then coat the wings with a yellow paint , where ever there is leak , blue prints will appear
I kown there are some big companys apply Helium leak detector in their production line. It's said that more precision could be achieved and thus the time to make -up charge be to 8 years(for home use split ones).
In our plant, there still use nitrogen +soapy water+keeping presure 24hr method. It still works for small volume production. I think it's no good for mass production.
My opinion is the better tech bring better quality ,but "fit for use " is more practical in some situation.
Hi Chemi,
have you looked at the thread titled "OFN or Not?" similar subject.
The more the technology advances the more tests needed , the more atmospher polluted the more tests needed .
Unfortunably high tec technics are still very expensive to use by small and medium companies . . . the goverments should support the price of such testing materials in order to develope their countries industries and their contribution in the atmospher clearness preservation
Hi Daddy cool.
No I didn't but I couldn't find it either, can you post the address so I can have a look?
Thanks
Chemi :)
Hi Chemi, :)
i think this is the correct one, you will have to excuse me if not, i'm on some spaced out medication at the moment and not really on this planet. good luck.
http://www.refrigeration-engineer.co...ead.php?t=2158
Hi Daddy cool,
What medication? Can I have some? :D
The use of OFN as I see it, is from two main reasons: One, the price.
Two, If you keep a small flow through a system while soldering, the pipes remain clean (no oxidation) inside, so it saves time and money on cleaning the pipe work.
Get Better,
Chemi :)
hi Chemi,
Try using Coloured liquid soap with OFN and you will be able to find smallest of leaks clearly this is the best method we use to find smallest of leaks.
Tejbir Singh
Hi Tejbir.
How do you mean, standard liquid soap which comes green or yellow? Or adding a bit of food colour or what?
Does the bobbles come out different?
Chemi :)
What do u mean Chemy by "food colors " never heard about this and want to learn more , can you please describe how it's used ? when to use it ? and the proportion you need ?
Thanks in advance
Hi ChemiQuote:
Originally Posted by chemi-cool
colour is not important, since the soap is sticky it stay even on vertical place say near pump end gaskets or near seal in open type compressors and leakage even of pin head bubles will create a whitish or light colour bubles which will accunlate at the site of leakage very effective and pin pointing, try this.
Tejbir Singh
I still dont understand..........perhaps if you dont mind Tejbir, explaining a bit more
Thx
Ayub i think that Tejbir means that colors will appear on soap , like if a soap bible is exposed to light , you can see colors in it
hi AiyubQuote:
Originally Posted by Aiyub
take any liquid soap apply it to the site where you want to check for the leak, if there is any leak even if its very small
you will see it in the form of white foam since the small bubles get trapped in highly viscous liquid soap. but remember to remove the soap with plenty of water since any trace will cause corrsion.
I hope this explaines the process try it once and you will get fond of this method.
Tejbir Singh
So whats this all about food colouring and all that ??? :rolleyes:
All it is is a bit of Fairy liquid!!! :D
Been using that for yonks............. :)
Boutros..............yes, those colours are the light spectrum !!!! :eek:
I guess that this is it, fairy liquid or any other soap and the colour is the bottle.
Chemi :)
Hehe , So that what was all about , Fairy soap lolololol , light spectrum , what about new technics
???
Nothing techie about fairy Boutros
Fairy is a famous brand washing up liquid in UK
And Chem youre wrong..............colour is not colour of bottle.
It is the translucent, effervescent colours of the rainbow when you blow Fairy bubbles!!!
And I forgot to add.............its so safe and good on your hands as well!!!
:)
Actually, food colouring does have a part to play in supermarket leak detection. :p
I always used to bung a bottle of red food colouring into a bucket of water when trying to find water leaks on the cabinets. That way, I could see where the water was coming from amongst all the other water that had already leaked & not been cleaned up! :D
I nicked the idea from geologists, who dye cave streams then search for the dyed water in the surrounding streams & rivers to find where the cave water system comes out.
I like the idea with using food colouring to find water leaks on cabinets....wish i thought of that a few months ago!! I think i`ll start carrying some in the car for the next time :)
Aiyub , i know that fary is very famous , it's famous here as well .
I am intersted in this food colors things , if someone have more information please post it
Im intrested in this colour thing as well now
The only thing I can think of is either,
Curry powder...........madras
Ayurvedi
Put us out of our misery Tejbir!!