leaked after pressure test

[klobber]

I recently pressure tested a chiller and it held its pressure for 48 hours..... however after two weeks when i came back to it it has leaked all refrigerant... is it possible for it to hold whilst static under pressure test then leak when its up and running???....... obviously it could be a new leak, and it was pressure tested to way over what it would run at..... just talking out loud really.....

[hoodemar]

it can be a new leak
but also it can be an old leak. which pressure u made ur test? but if now all the refrigerent leaked, in a big possibility it is a new leak. why u surprised so much???

[coolkid]

I recently pressure tested a chiller and it held its pressure for 48 hours..... however after two weeks when i came back to it it has leaked all refrigerant... is it possible for it to hold whilst static under pressure test then leak when its up and running???....... obviously it could be a new leak, and it was pressure tested to way over what it would run at..... just talking out loud really.....


Some questions for you:

1. What did you pressure test with - was it OFN?
2. What refrigerant is it on - is it a HFC?

If you pressure tested with OFN and the refrigerant is one of the relatively new HFCs, then it is probably because a tightness (leak) test will pass with OFN but there are still holes in the system big enough for the refrigerant to leak out.

If this is the case, you need to look at testing the empty system with either Heliun or an OFN - Helium mix.

The helium will find any leaks that you have and if you then cure these leaks, you won't have any problems when you put the gas in.

[sedgy]

hi , you say it was pressure tested way over over what it would run at, that might be the problem .
what psi did you test at, did you do a leak test after you had gassed it up ?

[monkey spanners]

Have you found the leak? And does the leak still leak with ofn?
If it does, its new leak, if it doesn't old leak.

[Grizzly]

Hi Klobber.
Nothing like keeping us all guessing then!
Would this chiller be charged with R407c by any chance.
I was working on one late into the night recently.
Were one of my colleagues had managed to finally identify a leak. (Clever Chap!)
After at least 3/4 attempts to prove the chiller gas tight.
It was on one of the condenser passes where the pipework goes through the aluminium end plate.

There was a hairline split in the pipe, which was so small. At ambient and under high nitrogen pressure.
It did not leak. Check whilst running and once the discharge pressure was high enough it started leaking.

In fact the split was only really visible when the heat was being applied to cap it with braze.

R407c is a nightmare!
Good Luck Grizzly

[desA]

Does anyone use die-pen techniques for crack detection? Would these be useful?

[Quality]

I have used it in the past but not refrigeration pipework

[klobber]

Hey, sorry for wait grizzly,ha...yeah it is 417a, the systems on here are 25 year old and have a history of being ''topped up'' something that really p....s me off as i have just done my 2079 and constantly getting told by my old lecturers this is not acceptable..... as i was when i went to college years ago... it was pressure tested to 16 bar, it has psv's on it which go to 18bar... used to be r22... the system like i say never leaked one bit previously!! im sure it could have leaked from shaft seal when up and running however no oil visible... i left the rig not long after it was running to come back 2 weeks later and find it empty however was told it was not running in that time as the weather is down out here and wasnt needed.... the oil company man was talking to me about new policy due to stricter regulations where we must prove the system hasnt leaked (over 30kg leak test every 6month) thereby all 4 chillers are currently empty and starting by eliminating 1 at a time we must pressure test, log whats went in then prove 6 month later that its not lost any.... so im gonna have to make sure it doesnt leak after a pressure test when up and running... just back into working on refrigeration after 4 year off.....

[That's too cold]

Does the chiller have high pressure relief valves? What are the bar setting? I have seen techs set the water tower fan cycling higher than the relief valves. So what happens, the head pressure builds up and the valve lift and releases most of the ***** before the fans cycle on.:rolleyes:

[Grizzly]

Hi TTC.
Personnaly I do not know of any R407c systems that use an evaporative Condenser.
I can't think even why anyone would, given the size of the systems that run on R407c?
Maybe you do things differently on your side of the pond.

Klobber.
Just out of interest what compressors are you running?
Cheers Grizzly

[That's too cold]

...Personnaly I do not know of any R407c systems that use an evaporative Condenser...
Evaporative Condensers will mostly be used in large ***** (R22, 407c) volume industrial refrigeration applications.

[Grizzly]

Evaporative Condensers will mostly be used in large ***** (R22, R407c) volume industrial refrigeration applications.

Err! Not over here. With a few exceptions they are mostly Ammonia Plant.
Yes there are some old systems with R22 but even they are getting rare.
Mainly because of the strict monitoring and chemical dosing required over here. (Because of Legionella Disease)
So has anyone else seen a R407c system with evaporative Condensers.
Grizzly

[dubati]

time for leak dye! run fro 24 hrs look see! or as other people say helium.

[oldmanads]

Without being too technical, have you checked the basics?? ie: o-rings on flanges, relief valves, bellows on oil pressure switches, o-rings on terminals etc... & you said that your pressure test held for 48hrs, but how long did your vacuum hold for?? what was the rise...

[iceytom]

Hi hope you find this useful, installed 6 Hubbard zenith unit back in dec/jan of this year all of then leaked after pressure testing at one point to 400psig (not safe) and leak tests and dye test i was still having leaks very frustrating until one day i leak tested with the unit switched on and used washing-up-liquid in a spray ok the old fashioned way, found leak on core plugs and why because some doss y so and so used PTFE liquid on them, problem was when the liquid receiver was cool (switched off) tight fit when (switched on) a nice and warm liquid receiver EXPANSION CONTRACTION
and i did bill Hubbard and got paid for my troubles

[BKS60]

See you stated the system used to be R22. How long ago?

If all the gaskets and orings are not replaced when the refrigeramt is changed they tend to shrink with the chlorine free refrigerants.

[Willem V]

(O-ring)seals are indeed mostly the problem, when you converse to "drop in" refrigerants as (DuPont Isceon refrigerants) R417A and R422D, you've to replace some seals before. Take notice of the retrofitprocedures, for example:
www.gas2010.com/.../ISCEON_MO29_R422D_Retrofit_guidelines.pdf (http://www.gas2010.com/.../ISCEON_MO29_R422D_Retrofit_guidelines.pdf)
www2.dupont.com/.../en.../k10921_MO59_uk.pdf