Pressure / leak test using ofn helium from BOC

[norfolkboy]

I am wondering if anyone has used helium ofn mix for finding leaks, BOC list it as a special gas part no 160268-v . At £27.06 a bottle it seems too good to be true and no one i have asked seems to have tried such a mix. Vulkan i think used to do it dut its not on their web site. i assume it needs a diferent sniffer.
many thanks.

[Tesla]

Hi Norfolkboy
I have not used it but when I did a days training on a lithiumbromide chiller I was told this gas was used like so... Big plastic bag covers chiller then i think helium is pumped into bag, chiller is pulled on a vacume and the discharge of vac pump is tested with helium detector to find if a leak is there or not.

[Brian_UK]

Hi Norfolkboy
I have not used it but when I did a days training on a lithiumbromide chiller I was told this gas was used like so... Big plastic bag covers chiller then i think helium is pumped into bag, chiller is pulled on a vacume and the discharge of vac pump is tested with helium detector to find if a leak is there or not.
Unfortunately that sort of test only tests to 1 atmosphere.

[nike123]

What is purpose of that test? For verification that unit is leak free, or something else. Isn't true that same thing is achieved with pressure test with OFN. Here, 40l botle of OFN is 6 pounds.

[norfolkboy]

hi Nike123,
I have a small vrf system and there is a leak on the pipe work or indoor units, as there is now no gas in the system following replacement of one leaking air handler coils i thought it would be easier to find the leak if i could use a sniffer to find the leak. The leak is a fair size approx 0.5 bar per hour from 25 bar. its a 410a system and some of the pipe run is above plaster ceilings and approx 70meters boxed in. There is a refnet joint that i can see but would need scaffold to check and thought with this much leaking we would be able to sniff it. The way i understand it its use is as a leak detection ? pressure test gas as BOCs web site talks about using your existing ofn regulator.
many thanks.

[The Viking]

The thought of using helium (or a helium mix) to pressure test goes back to when the "new" refrigerants were introduced.

As the new refrigerants got smaller molecules than our trusted old *****s it was said that a system could still be leaking even if OFN didn't escape from it.....

Personally, I never found a leaking system that passed a pressure test with just OFN But that's why some people recommended Helium or Helium mixtures for the pressure testing.
(Helium allegedly got smaller molecules than the modern refrigerants)

Norfolkboy,
Sorry but I can't see an easy solution to your problem.
The only thing I can think of is to cap off the pipes before and after the part of the run you can't get at, pressure test that section and, if found leaking, rent a tower and a wrecking bar.

I would also start the pressure test with 1/2-1 Bar of refrigerant before charging with OFN, just to enable me to find the leaks with my electronic sniffer.
But that's another story.

[norfolkboy]

good evening viking,
i just thought that this mix was a more acceptable / legal way of finding the leak.
some times you just wish you had never seen a job dont you?
thanks for your thoughts.

[nike123]

You could use sniffer. Just recover refrigerant, charge r410 or whatever refrigerant is in unit, to 1-2bar and then pressurize with OFN to max allowable pressure for system.
Then go thru the building and sniff with leak detector till you pinpoint leak.
Leak of that size you should find easy with correct electronic leak detector and this method.

Nature will excuse you for this test leak, because you actually reducing emission to nature.

[The Viking]

good evening viking,
i just thought that this mix was a more acceptable / legal way of finding the leak.

Might be, but the only leak detectors I've seen that would be able to pick up Helium are the ultrasonic ones and they would pick up OFN as well as Helium.


some times you just wish you had never seen a job dont you?

Mmm, couldn't agree more.
Today, I had to run a couple of hundred meters of DIII network cable..
All because some sparkie had cut parts of it up during a refurb in one area and we couldn't find the remains of our network in the jungle of cables pulled here, there and everywhere....:mad:

[lokringpete]

Gents,

Vulkan produce a product called Loktrace this does not contain Helium and is a very cost effective alternative.

Loktrace is detected by a gas specific detector, the blend is a Nitrogen/Hydrogen mix that has been scientifically blended to keep it totally inert.

To date we have had many sucessful experiences and will shortly be going to press.

This product is manufactured as a complete kit in the UK and has a patent pending, if you require any further information please ask.:)

[norfolkboy]

hi all,
has anyone tried this gas loktrace or know anything of if by reputation. i am very tempted to give it a try.
many thanks.

[Brian_UK]

Gents,

Vulkan produce a product called Loktrace this does not contain Helium and is a very cost effective alternative.

This product is manufactured as a complete kit in the UK and has a patent pending, if you require any further information please ask.:)
Pete, there is no mention of this product on the Vulkan website, can you please point us in the direction of some technical information?

[wdrzal]

Leaks should be picked up on with your Micron meter while in vacuum.

[nike123]

Leaks should be picked up on with your Micron meter while in vacuum.
Could you, please, explain procedure for locating leak with vacuum.:rolleyes:

[The Viking]

Could you, please, explain procedure for locating leak with vacuum.:rolleyes:

Or how ~1 Bar of negative pressure will prove anything on a system operating on up to 30 Bar of positive pressure?
:confused:

[Lowrider]

pressure testing on an absorption chiller is a no go! So the only way to check is as mentioned before.

Helium is indeed smaller than the new refrigerants. In fact Helium is the second element in the periodic chart and only larger than Hydrogen.

We use it sometimes if we can't find the leak with N2. We always find it with He!

[Plank!]

The OFN/Helium mix was our standard for some years in leaktesting the "new" refrigerants (i may be wrong here but i believe the mix was first made for star refrigeration for leak testing use.)
However its since been proven that the newer gasses have molecule sizes bigger than OFN so there is little point in helium for leak detection.
soapy water is by far the best method of tracking down a leak. The ultrasonic systems sound very good, I've not tried them, nor do I know anyone who has. I'm fairly certain that as the laws tighten with regard to leak detection that ultrasonic testing will become more common.
As for the hellium mix, forget it. Stick with OFN the helium given time will escape thru the copper, and even steel pipework - its not a leak its just one small atom squeezing thru the gaps in the alloy.
If you'd asked me this question 6 months ago I would have said use it, recent evidence has shown its just not worth the effort.

[nike123]

You could find that system leaks using vacuum, but you could not pinpoint where.

[Peter_1]

Vulkan produce a product called Loktrace this does not contain Helium and is a very cost effective alternative.

To date we have had many sucessful experiences and will shortly be going to press.


Vulkan makes the Lokrings and the Loktrace and the nickname is Lokringpete.
What a coincidence :o
I smell some free publicity :rolleyes:

[lokringpete]

Gents,

I make no secret of whom I work for, if i needed to I would have chosen a more subtle name and logo.

I apologise if offering a solution to a problem is deemed as free publicity it was never intended as such.

I would like to offer further information but I have no desire to be seen as using your site as an advert, so would somebody please advise how this can be achieved.

[The Viking]

If you got product leaflets / info in electronic format then you can either get you web monkey/master to upload it on your company website for download or send it to me and I will put it for download on my site.



And yes, on this forum we are a bit allergic to people with few posts telling us how great their products are, sorry.
(Call us old fashioned, but if your product really is the best thing since sliced bread, wouldn't one of our long-term members have mentioned it?)

[frank]

Hi Norfolkboy
I have not used it but when I did a days training on a lithiumbromide chiller I was told this gas was used like so... Big plastic bag covers chiller then i think helium is pumped into bag, chiller is pulled on a vacume and the discharge of vac pump is tested with helium detector to find if a leak is there or not.
On Absorption chillers there is a bursting disc fitted on the generator for safety reasons, and this normally bursts at just over 1 atmosphere.
Unless you remove this prior to pressure testing (which would render the test useless) you have to leak test these machines under vacuum.
Helium, having a smaller size molecule than OFN gives a much more accurate result.

[nike123]

Helium, having a smaller size molecule than OFN gives a much more accurate result.

Does anyone know what is difference in molecule size between R22 and gases composing R410a? I heard/read somewhere that R410a has components that have molecule size smaller by 20 times than R22.

[norfolkboy]

hi all thanks for the interest, just to let you know the job was a sub con job and the leak was found by others using 410a. but its now up and running.