Using Refrigerant for Leak Test Instead of Nitrogen! Dangerous?


Postby DIY AC GUY » Sun Aug 12, 2018 1:58 pm

Hi everyone, this is my first thread on DIYDoctor Forum since I am a newly registered member. The reason to why I had joined DIYDoctor Forum is because of questions like this one that made me worried lately. I am very concern about my safety and the possibility of the explosion of either the compressor or ac coils or maybe even my refrigerant jug/tank under certain situation. I just came from HVAC Talk but cannot get any proper response (I wish that I can ask a Pro on HVAC Talk). I tried to ask this question on HVAC Talk but they are very discriminatory towards us DIYs and not willing to give a basic safety advice even though, this is not really an elementary question but a question concerning safety and their philosophy is just not compatible with mine since I believe that anyone can do anything in this world especially if they do it correctly. Many of our home appliances are also dangerous such as a gas stove but we all learned on how to use it and went from novice to a pro. Many HVAC technicians in this third world country learned from looking at what other technicians do and maybe they did not even spend money to attend an HVAC school or take an HVAC course. If we do it correctly then it might not be dangerous. Maybe they are concern with legality or fearing for being charge with lawsuit if someone got hurt. (Of course, I do admit that there were non well trained DIYs that got killed in an explosion but this is something that can also happen to a professional based on the news that I had watched)

Before I will start, I just wanted to say that I am aware that using refrigerant instead of nitrogen for leak test is illegal in many states or countries in this world so I don't encourage anyone doing this but I am still curious to ask about it or like whether it is still possible in the terms of safety but not legally that we can still use refrigerant/freon for leak test instead of using nitrogen without exploding and risking to get killed. From what I know is that in the past, many people used to go with this old school method like charging ac unit with refrigerant like R22 (could deplete ozone layer and very toxic) for leak test but I still hear from many of the people in this third world country especially the DIYs who still use this method for leak test. Maybe it's because it is still not illegal in this country. All of my AC units use R22 since most of them are quite old except for the refrigerators that use R134A. (Not sure if I can replace R22 with R458A (Bluon) or R404A for R22 AC units since I don't know if my compressors use compatible POE oil or not)

So my question is: is it safe to charge refrigerant for leak test while the pressure is at 0 PSI but not at -30 PSI in case if there is a severe leak and it is impossible to use vacuum pump to pull down the vacuum down to -30 psi without risking to explode everything??? At zero psi, it means that there is still air or oxygen inside the ac coils. My first guess is that it is impossible for the air bubble to still be trap inside the ac system especially when there is a severe leak holes and the refrigerant was being charged into the system since refrigerant is heavier than air. I think that the effect might be the same like when we connect the gas hose to the refrigerant jug and we had to bleed the air out (of course it would not explode if it goes into contact with oxygen). Is it also fine if I charge it to 150 psi max (low pressure side) for leak test with R22 or with something like R32 (for Daikin R32 units)/R410A???? What scares me more is the mild flammable refrigerant like R32 and the lower flammable R410A and the presence of refrigerant oil inside the ac system... What is going to happen if I use one of these refrigerants for leak test at zero psi when there is still air inside the ac coils under severe leakage????? Would it explode??? I heard about explosion due to compressed air or compressed pure oxygen being used instead of nitrogen gas. I also hear about if compressed oxygen goes into contact with oil then it can still explode without ignition or spark. Is it as dangerous as compressed air or compressed pure oxygen???? (Assuming that there will no idiots nearby who would light up a cigarette or light up a brazing torch during this procedure and of course, I would not even dare to turn on the ac unit and the main circuit would be turn off)

(I heard about technicians mixing nitrogen gas with trace gas such as R22 for leak detector to work but I don't know about using 100% refrigerant instead of nitrogen for the leak test especially the flammable ones like R32 and R410A)

Sorry for my ignorance since I am just a novice DIY guy.....
DIY AC GUY
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Postby DIY AC GUY » Tue Aug 14, 2018 9:33 pm

UPDATED:

I think that I already got my answers since I had a created this same thread on the other website and I had a very long discussion there. This is a hot thread on diychatroom forum right at this moment and if anyone is interested then they can go to this link:

https://www.diychatroom.com/f17/using-r ... us-638767/
DIY AC GUY
Rank: Labourer
Progress to next rank:
25%
Posts: 2
Joined: Sun Aug 12, 2018 1:49 pm

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