Compressed dive air vs nitrogen leak detection

[saillar]

I am a MItsubishi Dealer here in the Virgin Islands and install a lot of Mini Splits. I am wondering about how you feel about pressurizing the line set before commissioning with compressed dive air. We pressure test all line sets overnight with dry air at 600 psi and if they pass we then do a triple evacuation with Nitrogen and charge. For years we couldn't get nitrogen so compressed dry air was all we had other than loading it up with R-22. This has assured me of a callback rate for leaks at less than .01%

[mikeref]

Hi Saillar, I don't know what to say except, you are kidding me right??? I really do not know how you have survived this long.. The last person i knew who ran out of nitrogen and actually used his industrial oxy from his oxy/acet set died.. TRUE story, Mike.

[NH3LVR]

I think what he is referring to is compressed DIVING air, which is somewhat dry.

[monkey spanners]

I think the risk is if you use air which has oxygen in, as, i assume all good diving air dose then if there is any oil in the pipe you are basically making a mitsubishi shaped diesel engine.

CO2 might be a better alternative.

[jpsmith1cm]

I think the risk is if you use air which has oxygen in, as, i assume all good diving air dose then if there is any oil in the pipe you are basically making a mitsubishi shaped diesel engine.

CO2 might be a better alternative.

I have used CO2 for years as an alternative purge gas and pressure testing gas.

Although it is dry, the free oxygen contained in diving gas could very well be a problem.

On re-reading your post, though, it seems that you may be testing the linesets separately from the unit.

If this is the case, I see no problems with your procedure.

[mikeref]

I think what he is referring to is compressed DIVING air, which is somewhat dry.

It just makes me shiver,600psi, diving air(how does one know moisture%), and refrigeration oil. My proceedure without OFN would be to leave system on vac test overnight. Never catch me using any air under high pressure except to blow clean condensers at 60 psi..Mike.

[NH3LVR]

I saw something like this on a thread the other day. I am not an expert on the subject, but I believe that the compressed air (which is still 21% oxygen) cannot cause a reaction. At least my air compressor has not blown up yet.

[mikeref]

I saw something like this on a thread the other day. I am not an expert on the subject, but I believe that the compressed air (which is still 21% oxygen) cannot cause a reaction. At least my air compressor has not blown up yet.

My thoughts were air under pressure, obviously higher than 100psi, and oil. Thought 21% oxygen did not matter for explosion to happen.. mike

[glenn1340]

I always use nitro to test with but I can`t see any big problem with using high pressure air especially if it`s been through a dessicant dryer. I work on air compressors up to 300 bar and I`ve never had any such incidents. However, I have had several oil/air separator fires caused by static build up in the separator element shorting to earth resulting in a violent explosion.
I know it`s going a bit off topic but if any of you guys are working on a lubricated screw air comp make sure the gaskets on the separator have a staple in it to ground it.

[Peter_1]

Hi Saillar, I don't know what to say except, you are kidding me right??? I really do not know how you have survived this long.. The last person i knew who ran out of nitrogen and actually used his industrial oxy from his oxy/acet set died.. TRUE story, Mike.

Mike, air is not the same as oxygen, he's even breathing the compressed air while diving.

[Peter_1]

It just makes me shiver,600psi, diving air(how does one know moisture%), and refrigeration oil. My proceedure without OFN would be to leave system on vac test overnight. Never catch me using any air under high pressure except to blow clean condensers at 60 psi..Mike.

In Europe, you may not start up if you haven't pressurized the whole system.

[chilliwilly]

When I use to work at LEC refrigeration back in the mid eighties. They put the evaporator and condensing coils in a kind of large chest freezer that was converted into an oven. And in turn the coils were heated inside it, and processed bone dry air were purged through them whilst they were heated.

Then the usual brazing and vacking out took place.

[mikeref]

In Europe, you may not start up if you haven't pressurized the whole system.

Interesting point. Have to look into Australian regulations.. mike.

[paul_h]

I don't know any split bashers (plumbers/electrcians/labourers licenced to install split systems) that even have a OFN cylinder or high pressure regulator. Bunch of yahoos that they are.

I took on another manufacturer warranty contract recently. Good work in the off months, but it summer it just sucks. The first three systems I looked at last week, all a year old and short of refrigerant due to dodgey flares.

Sick of arguing with these installers. I pump down, open the flares, see that they are all burred, call the installer.
Installer leak checks with what ever static pressure is left in the system like 1000kPa, claims no leak, that they have never had a leak in all the 100s of systems they've installed, not their problem!
Sick of telling them to **** off, look at that pathetic flare full of burrs, warranty void unless they re-flare properly after deburring the copper first. R410a will leak pretty good with a poor flare, I don't need to prove it!

[chilliwilly]

I don't know any split bashers (plumbers/electrcians/labourers licenced to install split systems) that even have a OFN cylinder or high pressure regulator. Bunch of yahoos that they are.

Yehaaah! ride'm cowboy.

I took on another manufacturer warranty contract recently. Good work in the off months, but it summer it just sucks. The first three systems I looked at last week, all a year old and short of refrigerant due to dodgey flares.

Sick of arguing with these installers. I pump down, open the flares, see that they are all burred, call the installer.
Installer leak checks with what ever static pressure is left in the system like 1000kPa, claims no leak, that they have never had a leak in all the 100s of systems they've installed, not their problem!
Sick of telling them to **** off, look at that pathetic flare full of burrs, warranty void unless they re-flare properly after deburring the copper first. R410a will leak pretty good with a poor flare, I don't need to prove it.

Yes I know what you mean, I've seen some pretty bad work and not just with fridge work neither. Some of the stuff that comes out of the factories these days aint what it could be neither.

Mind you there's a lot more YashiWanki stuff about these days that tries to claim its made in the same factories as Mits and the like. Who they trying to kid?

Mind you if the manufacturers don't listen, neither will the semi skilled folk. They'll just keep practicing the same mistakes that they see as the norm. Never mind though it will keep you in work, just make sure that you keep a good percentage of retention from their invoice.