AC testing with CO2

[2ndGearRubber]

Is anyone using a CO2 system for AC leak detection?

I'm looking into buying a system, and wanted some feedback on CO2 consumption volume. The vender I spoke to said their typical rental CO2 tank, with a CGA-320 fitting, is 50lbs. Google claims the typical fill pressure for a CO2 tank is 880psi.

My plan is a 150psi charge level for the AC systems.

 

[Desertskyy]

I have used nitrogen in the past. Many years ago I rented a tank from a welding supply place along with a gauge.

I found that a pressure relief valve on the back of my compressor had a very slight leak.

I also checked for leaks after a condenser replacement.

I will see if I have any notes anywhere with further info on what pressure I was running, volume etc.

 

[dnschmidt]

Doesn't Bernie Thompson make something for this that turns pink. I think the product begins with the letter B. Maybe Bullseye.

 

[RedneckWelder]

I haven’t heard about CO2 yet we use nitrogen (Mastercool and others sells a regulator kit for it). Convenient for us because we already have nitrogen cylinders on hand for charging hydraulic accumulators.

 

[danski0224]

Probably a moisture problem with using CO2.

 

[kbeefy]

I've used Nitrogen, and at a much higher pressure than that. 250-325# I think.

I recall seeing a leak detection system that I believe used CO2 at SEMA years ago.

 

[2ndGearRubber]

Doesn't Bernie Thompson make something for this that turns pink. I think the product begins with the letter B. Maybe Bullseye.

That's what I'm looking at. With tax and the AC system adapter for 134a, I'm looking at around $3000. CO2 detector system, and bullseye foam. I'm thinking I can break even in 30 repairs max, that's assuming an $500 repair and recharge total, which is on the low side.

Shop would be paying for the CO2 from our gas supplier.

 

[2ndGearRubber]

I haven’t heard about CO2 yet we use nitrogen (Mastercool and others sells a regulator kit for it). Convenient for us because we already have nitrogen cylinders on hand for charging hydraulic accumulators.

How does nitrogen work? Atmosphere is 78% nitrogen, so I assume you just use soap and water to look for bubbles?

 

[Desertskyy]

How does nitrogen work? Atmosphere is 78% nitrogen, so I assume you just use soap and water to look for bubbles?

I think I just sprayed the various fittings/connectors with 409 I believe. When it bubbled up I knew there was a leak or if it did not bubble then I knew I was good at that fitting/connector

The days of wasting Freon to chase leaks is over

I remember when r-12 was a dollar a can

 

[2ndGearRubber]

Gotcha. I'm trying to get leaks from the evaporator box, and areas not easily checked visually.

 

[texasprd]

I recently read an article on hagerty.com about leak-testing on auto A/C systems and the author mentioned C25 (C25 wasn't specifically mentioned but he said argon/CO2 mix and that's what C25 is) "for the tiniest leaks", as according to him an electronic tester/sniffer will detect argon.

 

[Jeepster04]

Could you not use anything as long as its 'dry'? Isn't that the concern, introducing moisture into the system?

 

[Steve_P]

I am not sure how you could detect nitrogen from a minuscule leak. Well, you can't. This is why helium is used in leak testing in industry; because it's a tiny percentage of the atmosphere

 

[bonneyman]

I used CO2 instead of nitrogen for leak testing. Being a liquid in the tank, CO2 had much more "gas" than a similar tank of N2. I also used it for blowing out dusty compartments. I bought a small hand held tank for carrying onto the roof. Alot lighter than the full tank (which I kept in the truck).

Most of the leaks I found were large enough to hear (or see with soap bubbles).

DiversiTech® Kit, Mini, Drain Kat™ - MBK-6 | DiversiTech

www.diversitech.com

 

[danski0224]

That's what I'm looking at. With tax and the AC system adapter for 134a, I'm looking at around $3000. CO2 detector system, and bullseye foam. I'm thinking I can break even in 30 repairs max, that's assuming an $500 repair and recharge total, which is on the low side.

Shop would be paying for the CO2 from our gas supplier.

I have heard that run of the mill CO2 isn't "dry" like nitrogen and it introduces moisture into a HVAC system. I'd certifiably ask about different grades of gas from the supplier. Carbon dioxide is used as a refrigerant, which is probably processed differently from CO2 as a welding shield gas.

That looks like an interesting system. A bit spendy as offered.

 

[danski0224]

I am not sure how you could detect nitrogen from a minuscule leak. Well, you can't. This is why helium is used in leak testing in industry; because it's a tiny percentage of the atmosphere

Pressure loss.

Also used to pressurize a small shot of refrigerant that a leak detector will pick up.

 

[2ndGearRubber]

Could you not use anything as long as its 'dry'? Isn't that the concern, introducing moisture into the system?

Yes, but CO2 has numerous advantages. Cheap, heavier than air, small molecular size, high pressures available for testing.

I am not sure how you could detect nitrogen from a minuscule leak. Well, you can't. This is why helium is used in leak testing in industry; because it's a tiny percentage of the atmosphere

Issue with helium is cost. Hydrogen 5% mix with nitrogen isnt flammable, but you're looking for tiny leaks, where only 5% of the leakage is now the gas youre testing for.

I have heard that run of the mill CO2 isn't "dry" like nitrogen and it introduces moisture into a HVAC system. I'd certifiably ask about different grades of gas from the supplier. Carbon dioxide is used as a refrigerant, which is probably processed differently from CO2 as a welding shield gas.

That looks like an interesting system. A bit spendy as offered.

I will speak with the vender about that. My ASSUMPTION was that pure CO2 would not have water contamination.

Thanks.

I'm learning that the stuff worth having, that makes me money, is inherently spendy. It's all about ROI.

 

[bonneyman]

10-4 As I recall the venting rules of the EPA at the time permitted a small amount of freon to be admitted with the nitrogen to allow detectors to work. The 'de minimus" clause. But that was early on - I don't know if that's still permitted.

As for not using CO2 in refrigerant systems, I called the CO2 manufacturer and talked to the technical department. The guy said yes CO2 was allowed to be used for leak testing but the prohibition was not to leave it inside the system for an extended time (like overnight) due to impurity contamination. For most leaks I heard or saw them (with bubbles) right away and bled the gas. But a small leak requiring pumping it up and leaving it a while to check for a pressure drop was out.

 

[2ndGearRubber]

10-4 As I recall the venting rules of the EPA at the time permitted a small amount of freon to be admitted with the nitrogen to allow detectors to work. The 'de minimus" clause. But that was early on - I don't know if that's still permitted.

Right, but the detectors arent finding the leaks at 90psi of straight refrigerant.

Charge it, comes back 12 months later half full. No dye to be found, no oil residue. Those are a massive PITA, and can be warranty if it doesnt last XYZ amount of time.

I want to find ALL the leaks, the first time, and fix it. That, and have a better option for evaporators. CO2 being small and heavier than air being a huge plus. Plug the drain hole, check the whole system, unplug it and see if CO2 collected.

 

[Wrench97]

How does nitrogen work? Atmosphere is 78% nitrogen, so I assume you just use soap and water to look for bubbles?

Usually used with a little bit of freon for a tracer and a electronic leak detector or soap bubbles.
This method is popular in the HVAC/Commercial refrigeration side and they were touting it 10-15 years ago for reefer trailers.

 

[danski0224]

Right, but the detectors arent finding the leaks at 90psi of straight refrigerant.

What kind of detector? I've had pretty good luck with an infrared detector vs a heated unit.

It still isn't perfect, but much better.

I will speak with the vender about that. My ASSUMPTION was that pure CO2 would not have water contamination.

Thanks.

I'm learning that the stuff worth having, that makes me money, is inherently spendy. It's all about ROI.

The foam seems to be the only specialty item... at least in the basic kit. Much of the rest of it can be found in welding or HVAC supply houses.

I wonder how well it would work in non-automotive applications.

 

[dnschmidt]

CO2 is going to be dry no matter what since it's a liquid under pressure. Welding hates moisture more than damn near anything so moisture in a welding CO2 bottle seems like a red herring to me. The water should be frozen out during the air separation process.

 

[bonneyman]

Right, but the detectors arent finding the leaks at 90psi of straight refrigerant.

Charge it, comes back 12 months later half full. No dye to be found, no oil residue. Those are a massive PITA, and can be warranty if it doesnt last XYZ amount of time.

I want to find ALL the leaks, the first time, and fix it. That, and have a better option for evaporators. CO2 being small and heavier than air being a huge plus. Plug the drain hole, check the whole system, unplug it and see if CO2 collected.

I know this sounds crazy, but it's true.

I once worked for a company that had a guest house and swimming pool behind the shop. (It all came as one thing when they bought the shop building). Nice for company parties and such as we could take a dip.
Well, this owner was not above using the pool for leak testing! He'd dunk a charged window unit under the water, and after 15 minutes when all the trapped air bubbles were gone you'd see the freon leak! For those really troublesome leak problems. lol

And once he used an engine hoist and lowered a 3 ton condensing unit in there. We couldn't find the leak, the customer was coming unglued, so he had us remove the condensing unit, haul it back to the shop, and dunk it. IIRC we then found the leak.

 

[2ndGearRubber]

Usually used with a little bit of freon for a tracer and a electronic leak detector or soap bubbles.
This method is popular in the HVAC/Commercial refrigeration side and they were touting it 10-15 years ago for reefer trailers.

Soap and bubble sized leaks I can find all day, those will have a system empty pretty quick. I'm chasing the "1lb system needs charged every 12-18 months" sized leaks.

What kind of detector? I've had pretty good luck with an infrared detector vs a heated unit.

It still isn't perfect, but much better.



The foam seems to be the only specialty item... at least in the basic kit. Much of the rest of it can be found in welding or HVAC supply houses.

I wonder how well it would work in non-automotive applications.

I have 2 leak detectors, plus I dye charge all systems. An inficon whisper ultra sonic style, and an inficon dtek select are my detectors. Typically I will use the dtek, not wildly impressed with the whisper. Good for shrader valves and very large leaks. I change the sensing tip yearly on the dtek. It's a great unit, dont get me wrong, its infrared. I'm trying to increase my leak finding rate, and do so in less time overall. Even on high sensitivity levels, these leaks are so small and the molecules of 134a so large, that it's hard to track down leaks quickly. I like detectors for checking single junctions post repair, they work very well for that. On a 70*F day, I only have 70psi to find the leak. Looking at a 134a molecule, its massive compared to CO2. And I can run 150psi of CO2 maximize leakage.

I did consider building my own setup. The 134a hose conncetion, and the high side regulator isnt a big deal. The evap leak 1psi with built in leakage flow rate meter, relative to leak diameter, is another story.

I can often diagnose a car with a snap on scope, or even a uscope. But for anything complicated the pico is just a better tools more directly suited for me use. I'm guessing the bullseye kit would be the same, guessing.

 

[unslow1]

I'm sure those in this discussion probably saw it but Bernie posted a video on this a couple of days ago.

 

[2ndGearRubber]

I'm sure those in this discussion probably saw it but Bernie posted a video on this a couple of days ago.

I've been thinking about this kit for a long time, and that video pushed me to realistically look into the viability.

 

[dnschmidt]

Bernie Thompson is a genius. You might not like the prices but the dude is a genius and you got to pay a genius.