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