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Thread: Evasive gas leak
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19-02-2005, 08:25 AM #1
Evasive gas leak
I have finally found and repaired a gas leak which I found on the 5/8 soft drawn copper pipe liquid line of a freezer room.
The gas was sprayng out of a pin hole in the 90 degree bend of the tube.
This bend was formed with a pipe bender.
There were no welds where the leak developed and it was not possible that someone could have physically damaged the pipe. There was no vibration or any stress on the pipe.
The system has been leak free for 5 years.
The refrigerant is 507.
In my efforts to trace this leak I used almost every leak detection method I am aware of without success.
My success rate of tracing a leak in all other systems has been 100% at the first attempt so you can imagine my frustation when I was not able to trace this evasive leak.
How is it that a leak developes like this for no apparent reason and only leaks under circumstances when you are not on site?
Any one have a similar experience?
Cheers,
Feeze
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19-02-2005, 09:35 AM #2
Re: Evasive gas leak
Last year (2004)has-been for me the'' year of leak''.i have 4 same fault, 1 open dispay cabinet 2 auto AC , 1 a small coldroom.I hope that kind of fault will pass beside me, this year .
what quantity of refrigerant has-been in this plant ? in how many time did he lose the refrigerant?
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19-02-2005, 09:50 AM #3
Re: Evasive gas leak
The system takes about 10 kg 507.
The system had to be toped up with 5kg every 7th day.
Today is the 10th day since fixing the leak and I have not had a call out so I am on the verge of celebrating but I still have to climb the hurdle of invoicing the customer.
Cheers,
Feeze
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19-02-2005, 09:53 AM #4
Re: Evasive gas leak
once in a large supermarket I had a whole length of suction line on top of a cold store that was setting off the parracense leak detection system. The copper had seemed to become pourus with lots of microscopic holes. has any one else ever come across this before?
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19-02-2005, 10:07 AM #5
Re: Evasive gas leak
Dill,
This leak also occured on the the roof of the freezer room but it was on the liquid line. Once when the building was still new there was a leak from the roof of the building.
The rain water fell on the piping at the point of the leak.
I am wondering if this was perhaps a catalyst in starting a reaction- just grasping at straws.
Cheers,
Feeze
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19-02-2005, 10:11 AM #6
Re: Evasive gas leak
The best practise to detect those small pinhole leaks is to evacuate the refrigerant, top it with OFN + helium and use soap.
In closed places, the electronic gadgets go wild.
Holes in copper tubes, indicates low copper quality.
Chemi
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19-02-2005, 10:22 AM #7
Re: Evasive gas leak
Hi Feeze, good job you don't work in the uk, as your addmission to topping up systems would bring you into conflict with the Enviromental protection act. Possible £20,00.00 fine and / or inprisonment ???. Problem sainsburys had with large copper pipe some time ago was 1) the quality of the pipe and 2) installing engineers useing scented talcum powder to slip insulation onto pipe. This reacted with moisture and attacked the surface of the copper. Most good installers now use french chalk to ease installation of insulation.
it's only a fridge, fix it. ;)
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19-02-2005, 11:53 AM #8
Re: Evasive gas leak
A Little trick with slipping the insulation on,
I use a wide (50mm) insulation tape on the pipe and then slip on the insulation.
Works like Vaseline in other activities
Chemi
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19-02-2005, 02:22 PM #9
Re: Evasive gas leak
once in a large supermarket I had a whole length of suction line on top of a cold store that was setting off the parracense leak detection system. The copper had seemed to become pourus with lots of microscopic holes. has any one else ever come across this before?
i have also came across this situation but my boss`s won`t beleive me, but im glad to here of it elsewhere cos i was starting to doubt myselfIF AT FIRST YOU DON`T SUCCEED.
DESTROY ALL EVIDENCE THAT YOU TRIED!
and go get a cuppa
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20-02-2005, 04:12 AM #10
Re: Evasive gas leak
Originally Posted by Feeze
Did your electronic leak detector go off when you were trying to find this leak.It must have been going crazy.
I got called to a system once that another company had been putting about 5kg every 10 days into for approx 6 months.It was into a pub system.Leak wasn't too hard to find.I walked onto the front doors of the pub with the detector turned on.It went nuts.
I use a Javac tek mate.But even though it says for use with r134a.I sometimes have leaks that you can see with soap,but the detector hardly goes off unless you are right on top of the leak with r 134a.Anyone else have this kind of problem?
Regards.
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20-02-2005, 06:21 AM #11
Re: Evasive gas leak
Temprite,
Yes, the leak detector did go crazy when I walked in the shop,
but only on the last time when the leak was visibly spraying out.
I have a D-Tek electronic leak detector which can detect most
refrigeration gasses. I have had lots of successful stories with it.
I also used the ultrasonic method, the ultraviolet dye method and the soap bubble method on this system.
I found other minor leaks on this system while searching for the main culprit. These I repaired thinking that they may have been the cause of the gas shortage but to no avail, the culprit remained hidden. Any one else would have walked away from this problem but I persivered, I refused to allow myself to be beaten. As someone else on the forum said " Its only a fridge- fix it"
Cheers,
Feeze
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20-02-2005, 05:54 PM #12
Re: Evasive gas leak
installing engineers useing scented talcum powder to slip insulation onto pipe. This reacted with moisture and attacked the surface of the copper. Most good installers now use french chalk to ease installation of insulation.
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20-02-2005, 06:35 PM #13
Re: Evasive gas leak
I hope this isn't true
Chemi
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21-02-2005, 10:30 PM #14
Re: Evasive gas leak
ultra sonic leak detector are thay any good
i have benn thinking of buying 1 ????????????
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22-02-2005, 06:42 AM #15
Re: Evasive gas leak
I have one, don't do it.
They're in py opinion made for other purposes.
Frank, we use exactly he same powder from Johnson, but last month, we forgot the bottle at home and bought some chalk in the nearby DIY-shopIt's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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22-02-2005, 06:53 AM #16
Re: Evasive gas leak
My experience with ultrasonic leak detectors have been very good.I have pinpointed gas leaks where my electronic leak detector goes crazy due to the over contamination of the leak in confined areas such as piping in tranches and eveporators in cold rooms.
I use the electronic leak detector to locate the general area of the leak and then zoom in with my ultrasonic leak detector.
For me it has been a valuable tool.
Regards,
Feeze
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22-02-2005, 07:02 AM #17
Re: Evasive gas leak
Can't you reset your leakdetector to a new higher concentration level or starting level so that it doesn't take in account the gas in the room?
What ultrasonic do you use? Perhaps I use it the wrong way.
My experience with the ultrasonic is that you always must be right on the leak before you can trace it.
And if you find it then finally, mostly you then even can hear it if it's very quit.It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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22-02-2005, 12:36 PM #18
Re: Evasive gas leak
Peter_1.
Yes I have an excellent electronic leak detector which I can reset to the higher surrounding concentration of gas until I find the leak and I have been successful in about 95% of my efforts.
In the other 5% of the cases other methods are required,
the soap bubble method-when you know where the leak is and you have good excess to it but you need to know if it is the whole joint or only a small part of the weld,
the dye method I found works well for leaks at the shaft seal of open drives,
and the ultrasonic which as I said before worked for me in pipe trenches where the gas concentration is saturated and there are so many pipes that you do not know where to begin looking.
Also in eveporators in cold/freezer rooms where your electronic leak detector indicates that there is a leak, I find that I am able to zoom in to the offending eveporator (if there is more than 1)
and probibly the vicinity of the leak but if the leak is in the middle of the eveporator 2 or 3 rows deep, than my ultrasonic detector works best in pinpointing that leak.
So what I am saying is that I use them together.
I have an AccuTrak VPE-1000 Made by Superior Signal their top of the line unit.
My electronic leak detector is a D-Tek all gas unit also their top of the line
I use Spectrolites ultraviolet kit for the dye method.I found that their big bulb works better than the blue diode flash light from cliplight. However I accidently found out that the blue diode flashlight from cliplight is wonderful for revealing hotspots and arcing in electrical boxes.Try it out and all will be revealed.
Regards,
Feeze
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22-02-2005, 10:46 PM #19
Re: Evasive gas leak
Originally Posted by Temprite
We now use the yokogawa H10 pm witch is so sensitive that even a small leak, not vissible using soap can be measured holding the probe in the airoutlet.
This piece of kit has a 3 level auto sensing setting and when encounterd with big leaks you can switch it to hand ajust with also has 3 settings and a potentiometer to increase or decrease the sensetivity.
Recently I came among a extreem large leak where even on setting large and totaly turned back it went crazy.
On the bottom is a other ajustment where you can ajust the temperature of the sensor, by turning this back I could locate the leak wich was in a insulated liquid line above a false ceiling.
I can tell you that after al lot of leakdetectors passed throug my car this one is by far my favourite.
Documentation can be found here
http://firsttechtools.com/yokogawa_h10_pm.htm
Regards Victor
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23-02-2005, 06:08 AM #20
Re: Evasive gas leak
Originally Posted by coolman
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24-02-2005, 07:32 PM #21
Re: Evasive gas leak
Originally Posted by Feeze
R22
R134a
R401a
R402a
R404a
R507
R404 is the most difficult one to sense, and even very small leaks are found very easely.
Regards Victor
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24-02-2005, 07:49 PM #22
Re: Evasive gas leak
Frank, we use exactly he same powder from Johnson, but last month, we forgot the bottle at home and bought some chalk in the nearby DIY-shop
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27-02-2005, 06:16 PM #23
Re: Evasive gas leak
Here is a link to info on leak detection methods
http://www.bacharach-training.com/methods.htm
Cheers,
Feeze
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18-08-2008, 04:56 AM #24
Re: Evasive gas leak
The best and sure way to find any leak is to decant system (unless R22) add some R22 and pressure test with OFN.Then get the old butane leak lamp out.
Never failed me.
a/c Doctor
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18-08-2008, 07:22 AM #25
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