INERT GAS PRESSURIZATION?

[Vettepilot13]

Hi all! First post--> please be kind! ;~)

So, I have several projects that require using inert gas pressurization, and I will need about 20 to 200 psi delivered. I just do NOT have the bucks right now to buy a Nitrogen regulator, tank of gas, etc., etc. So, as is often the case in my life, I need to cobble something together. Here's what I have available:

Regulators:

Mig welding Argon regulator
Mig welding 75/25 Co2/Argon regulator
Torch Acetylene regulator
Torch Oxygen regulator

Gases:

Pure CO2
75/25 CO2/Argon
Oxygen
Acetylene

So, from my stock, the pure CO2 or the 75/25 would work for the inert gas. But which regulator? I don't think the Mig regulators will regulate/dispense as high as 200 psi, and perhaps the Acetylene regulator might not either. I just can't find any info on the max pressure of the Mig regulators. All that is usually figured in CF/H, and is low pressure normally at that. Anyways, it's kind of looking like it might come down to using the Oxygen regulator as I think it will go to 200 psi delivered, "cobbled" together with either the CO2, or 75/25 CO2/Argon.

(Note: I'm sick in bed right now, and my equipment is in storage, so I'm trying to just figure this all out from here at the moment...)

Thoughts everyone??

One of the uses will be high pressure testing of a super tough to find leak in my auto A/C system. I know this is done, but have never done it myself. Do you hook your pressure to both high and low sides of the A/C?

Thanks for any help! (Note: I use the term "cobbled together", but I'm fully aware of the dangers of high pressure gases and have great respect for them. I've been a fabricator for nearly 60 years...)

Vettepilot13

 

[jsaw]

I have heard of nitrogen and soapy water being used to find a/c leaks, but it would have to be what I would consider a large leak for bubbles to show up. . I have always used an a/c leak detector, or leak trace dye. Depending on how big the leak is, they can be a real pain to find.

 

[BigMike782]

You need an HVAC purge regulator.
Welding regulators are set up for flow( ** psi @ ** cfh)

 

[Firebrick43]

Hi all! First post--> please be kind! ;~)

So, I have several projects that require using inert gas pressurization, and I will need about 20 to 200 psi delivered. I just do NOT have the bucks right now to buy a Nitrogen regulator, tank of gas, etc., etc. So, as is often the case in my life, I need to cobble something together. Here's what I have available:

Regulators:

Mig welding Argon regulator
Mig welding 75/25 Co2/Argon regulator
Torch Acetylene regulator
Torch Oxygen regulator

Gases:

Pure CO2
75/25 CO2/Argon
Oxygen
Acetylene

So, from my stock, the pure CO2 or the 75/25 would work for the inert gas. But which regulator? I don't think the Mig regulators will regulate/dispense as high as 200 psi, and perhaps the Acetylene regulator might not either. I just can't find any info on the max pressure of the Mig regulators. All that is usually figured in CF/H, and is low pressure normally at that. Anyways, it's kind of looking like it might come down to using the Oxygen regulator as I think it will go to 200 psi delivered, "cobbled" together with either the CO2, or 75/25 CO2/Argon.

(Note: I'm sick in bed right now, and my equipment is in storage, so I'm trying to just figure this all out from here at the moment...)

Thoughts everyone??

One of the uses will be high pressure testing of a super tough to find leak in my auto A/C system. I know this is done, but have never done it myself. Do you hook your pressure to both high and low sides of the A/C?

Thanks for any help! (Note: I use the term "cobbled together", but I'm fully aware of the dangers of high pressure gases and have great respect for them. I've been a fabricator for nearly 60 years...)

Vettepilot13

do you use sandwich bags because condoms are to expensive?

 

[Vettepilot13]

Nice...

I guess you're the type that never needs a hand.

Vettepilot

 

[DenisG]

Here's a CGA selection chart for various gases:

CGA - Gas Valve & Fittings Selection Chart | All Safe Global

allsafe.net

 

[Firebrick43]

Nice...

I guess you're the type that never needs a hand.

Vettepilot

I am the type that uses the proper tools and consumables. If I dont have it, and its a one time thing, I barrow it from friends that I have formed good relationships with and failing that I rent it as any decent welding shop will do with a mini bottle.

I dont jerry rig things.

 

[beemerphile]

I have heard of nitrogen and soapy water being used to find a/c leaks, but it would have to be what I would consider a large leak for bubbles to show up.

Forget the soapy water and use the right stuff and you can find small leaks.

 

[American Locomotive]

Yes you can use different regulators on different gasses.(except oxygen, which should always be used with an oxygen regulator)

The oxygen regulator will regulate to the pressures you want, but it has a different threaded connection and will not fit co2, argon or nitrogen bottles.

The other regulators won't get to high enough pressure.

A nitrogen regulator with your pressure range will screw into your argon and co2 bottles. They're less than $100 online. I suggest you just wait month or two and save some money.

 

[Firebrick43]

Also note that CO2 or CO2 mixes are not inert, they are simply a shielding gas to exclude oxygen.

CO2 can and will form carbolic acids in the presence of moisture. This is why CO2 bottles are retested on a 5 years instead of 10

There is a reason nitrogen is used, although pure argon is ok if you have it for tug welding/mig aluminum, it’s just more expensive which is why it’s not typically used.

 

[Chance]

If your a/c system has already at 0 pressure (leaked out all the refrigerant), its fine to use plain old air to find a leak, since you will be replacing the receiver / dryer since the system has been exposed to water vapor in the air (receiver dryer contains desiccant that ***** up the water fast. What you need is a manifold gauge set ($50 at HF/amazon). You only need nitrogen if you think the receiver / dryer is still good (but its not if the system has been open to air for 24 hours). The receiver / dryer is cheaper than the charge of refrigerant you'll be adding once the leak is sealed. Lots of good videos on youtube covering all of this. I just diagnosed a leaking compressor seal on my car this way, changed the compressor, and then as long as the system was open to the air, changed all the o-rings and the receiver dryer. You'll need a vacuum pump if you're going to add the refrigerant yourself, or you can go to any a/c shop to have it evacuated and the refrigerant added, but you'll want to do this immediately after swapping in the new receiver/dryer before it absorbs too much moisture from the air in the lines.

 

[Walkers]

None of the gasses you listed is inert.

 

[Vettepilot13]

Thank you for the answers guys.

I have serviced and repaired quite a few A/C systems--> have gauges, vacuum pump, etc. But this one has a slow leak I just can't find.

When pressure testing as I propose, do you apply the testing gas pressure to both the high and low sides at the same time??

Thanks again,
Vettepilot

 

[American Locomotive]

Most would probably pressurize both sides, but it isn't strictly necessary if the system doesn't have a blockage.

 

[no704]

Pump some UV die in to it and pump shop air in.

 

[jsaw]

Thank you for the answer

When pressure testing as I propose, do you apply the testing gas pressure to both the high and low sides at the same time??

Thanks again,
Vettepilot

With the system not running, Both sides of the system should equalize, so it does not matter which side you pressurize

 

[tester19]

If the vehicle is anywhere close to modern it already has UV dye in the refrigerant from the factory. I have used N2 but it was a hassle to setup as posted above. Plus do you have a source for the N2? I just use plain old compressed air now. I used several adapters to get the air line connected to my AC gauges. Yes I open the Hi and Lo side valves but it really does not matter because you can't stop the system for equalizing no matter what you do. It's all connected.

I find pressure finds the leaks in the system way faster than vacuum does. The down side is air has moisture in it as posted above. BUT you looking for a leak and will vacuum down the system before filling so this will get the moisture out of the system.

Listen to jmcq above and be sure to change the dryer if the system is charged with compressed air! I have found that dryers are neglected so I will change them if possible anyway. Pretty cheap these days especially if you have desiccant bag setup.

The last AC work I did I finally got a new set of AC gauges from Eastwood on sale. My old set up did not have the nice quick connect fittings for the high and low side connections. Just the old screw on ones. Vacuum down the truck and could not hold a vacuum? Went thru Hell checking and rechecking everything before trying the compressed air trick. Well what do you know but I had leaks from my new gauge set because I had not firmly tightened down all the fitting! Yes user error for sure!

I also recommend a real bubble leak detector instead of soapy water. Yes there is a difference. I use Better Bubble but there are a ton out there and it does not go bad so for under $20 you can have right stuff.
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