Pressure testing an AC system with CO2

[gman994]

I realize this may sound like a foolish question, but I was curious if anyone ever uses compressed CO2 as a substitute for nitrogen for pressure testing lines. I have heard there is excessive moisture in CO2, but, I ran a little test with a Totaline cartridge kit, and with a sightglass moisture indicator, and they both came up negative (dry). If the CO2 is relieved, and the system is swept with refrigerant and evacuated thoroughly, (along with new drier), wouldn't the same result be achieved? This came up in discussion with another tech, and though we use nitrogen as a general rule, there are times.... Thanks for any replies, --- gman

[VTP99]

I have used customers CO2 if I ran out of nitro on the job. The last time I checked they were about the same price to fill. Dry CO2 is hard to get and cost a lot more. I think the best thing about CO2 is the aluminum cylinders. :grin2:

[jpsmith1cm]

I've done it.

You are evacuating anyway, what's the big deal?

[jimf46939]

I assumed there would be a lot of moisture but if you used a moisture indicator and came up with both of them dry. Go for it. I will continue to use nitrogen.

[Nixtopher]

I wouldnt do it. The manufacturers all recomend nitrogen by golly

[ZeroTolerance]

Sometimes you gotta do what you gotta do in certain situations. If you run out of nitrogen while on the job then yes, I would use what inert gas was available on site. Like JP said, you are going to evac anyway.

[Dallas Duster]

I remember seeing documentation one time about the differences between the two and the moisture content was almost identical. It`s been several years I wish I would have kept that info.

[DFZ]

I wouldn't worry about the moisture it adds, I would worry about it reacting to moisture in the system period to make carbonic acid, moisture will come out with a vacuum pump, acid is there to stay and cause havoc.

[mizzouhvac]

I have used co2 in a pinch. Like the guys said sometimes you gotta do what you gotta do on the job site to take care of a customer. I always figured that if I am evacuating to 500 microns the system will be good and dry anyway.

[joeyd]

I wouldn't worry about the moisture it adds, I would worry about it reacting to moisture in the system period to make carbonic acid, moisture will come out with a vacuum pump, acid is there to stay and cause havoc.

As I understand it, carbonic acid cannot exist out of solution at normal temperatures. Removing the moisture effectively removes the acid.

[btuhack]

Trick question for only those who claim to not cut corners, BUT have negotiated the use of CO2.

Scenario
Same repair, no N2 on roof... no purge obviously, but hey,it's all good. Now your micron gauge is dead.

Do you:
A)still squeeze the system to complete the work? or
B)stop, leave, get a new micron gauge(and N2 while out) then return to finish as per industry standards.

[jpsmith1cm]

Trick question for only those who claim to not cut corners, BUT have negotiated the use of CO2.

Scenario
Same repair, no N2 on roof... no purge obviously, but hey,it's all good. Now your micron gauge is dead.

Do you:
A)still squeeze the system to complete the work? or
B)stop, leave, get a new micron gauge(and N2 while out) then return to finish as per industry standards.

CO2 is an inert gas no different than nitrogen is.

I've successfully used both as purge gasses as well as for pressure testing.

I'd also done a couple of evacuations without using a micron gauge.

Guess what... It works. Get over it.

[btuhack]

I got nothin to to get over buddy. I freely admit to cutting corners here and there/mistakes.

I want the opinion of those who "claim" to not cut corners, then do so.

Wondering where "those" folks draw the line

[david chamberla]

i got stuck with argon once had to use new it was safe but expensive whent back to the welding shop exchanged the bottle told them iam glad it was not oxygen of corse i look at my tanks ,there was no charge for the argon .got to do .some days ,