How to make your own CO2 air system for under $200

mrblaine said:
I understood what you were comparing. I'm just one of those that has been around far too much bullshit when it comes to compressed gases to take much at face value. I'm lucky that I have some engineer type folks as very good friends who I use as a resource when I don't know something myself. When I worked at the ambulance company there was a common story about being careful with O2 because you could saturate a patient's clothes with it and cause them to spontaneously combust. The next one was that O2 is flammable. I would hold a lit cigarette in front of the valve on one of the small bottles and open the valve to show them that O2 doesn't burn, it supports and enhances combustion but does not itself combust. There was always about half the group watching that would turn and run when I cracked the valve open.
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LOL. I bet those guys had to clean their pants. As you well know and most people would too if the just thought about it for a sec. You can have a sealed room full of O2 and it wouldn't go off and a spark and you will find yourself in the next life. It just feeds the flame. Has everyone seed the movie Backdraft?
 
JP98 said:
Hi @mrblaine I wasn't disputing Boyle's law and nitrogen. I was just stating that it held in a tire slightly better than say compressed air or CO2 and it was better at heat distribution. The heat distribution coming from the fact that it being a single molecule gas vs air(78%N, 21%O balance other gases). Wasn't saying that it was the end all be all for tire inflation. I agree with your other statement about Nitrogen tire fill being snake oil. I build nitrogen gas generators and only top my tires off with it if they need it when I'm here. At the house I use my air compressor.
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As it relates to how we use our tires, what would the average person notice that would tell him that there is better heat distribution in his tires? If I understand Mr. Boyle, once the tire is filled with any of the common gases, for a given volume and temperature, the pressure will be identical and the tire will change pressure at a given rise or reduction in temperature. What did I miss?
 
mrblaine said:
As it relates to how we use our tires, what would the average person notice that would tell him that there is better heat distribution in his tires? If I understand Mr. Boyle, once the tire is filled with any of the common gases, for a given volume and temperature, the pressure will be identical and the tire will change pressure at a given rise or reduction in temperature. What did I miss?
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The average person wouldn't see really any benefit. We don't push tires to their heat extremes.

Boyle's law states that The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system. The law fails when you are talking about a multi molecular gas like CO2 due to the way carbon atoms and oxygen atoms react to heating or cooling. They will react different to a single molecular gas like nitrogen because you don't have the two different atoms reacting in their own way.
 
UPJOHN said:
I thought of filling my tires with helium. Thinking it would float over them potholes and bumps.
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Of course it would. Everyone knows the helium is lighter than air. I'm sure if someone thought they could get away it they would be trying to convince everyone to pay $50 bucks a tire to have them inflated with it.
 
JP98 said:
The average person wouldn't see really any benefit. We don't push tires to their heat extremes.

Boyle's law states that The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system. The law fails when you are talking about a multi molecular gas like CO2 due to the way carbon atoms and oxygen atoms react to heating or cooling. They will react different to a single molecular gas like nitrogen because you don't have the two different atoms reacting in their own way.
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As stated previous, I ran this by my gas guru, my physics professor with a PHD, and my engineering mentor and they asked if you could provide some sort of reference they could peruse to help them with their understanding of the multi molecular nature of a gas that precludes it from reacting according to The Ideal Gas Law. When they looked it up at my request just to verify that they hadn't missed anything, the explanation made no exceptions for Co2 or any other poly molecular gas.
 
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Dozerdude said:
Let's go back to co2 for lockers, can it be done or will I have problems? Thanks
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How are you going to set it up?
I have an adapter I put together that plugs into the quick disconnect on the center port of my ARB compressor tank. I used a street tee so I could install the pressure switch and a QD into the same port. The fitting has a small regulator so I can control the pressure going into the tank from my Co2 tank. I built it so I could have an alternate compressed gas source to activate my lockers in case of compressor failure. I've been carrying it in the glove box since I put the ARB compressor in many years ago and have never used it.

Again, how are you going to set it up and what advantage will you have over one of the mini ARB compressors?
 
I'll be honest I have not done any research yet, won't have a ARB until late summer. My thought was run a line off the co2 tank, to an air switch from a truck, regulate it down between the switch and locker. Does this sound correct? Thanks Mr. Blaine
 
Dozerdude said:
I'll be honest I have not done any research yet, won't have a ARB until late summer. My thought was run a line off the co2 tank, to an air switch from a truck, regulate it down between the switch and locker. Does this sound correct? Thanks Mr. Blaine
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No, you have to have a regulator on the tank. It is 8-900 psi typically and you don't want that much high pressure line routed anywhere in a vehicle unless you really know what you are doing and have a reason for doing so.

Other than that, the regulator can be up to around 175ish PSI which will work nicely for tire fills and run the locker.

I wouldn't do it that way, I'd keep the Co2 for tires and get the small ARB compressor and use that for the locker(s). They work well, gives you a redundant system for your lockers if you make a way to use Co2 in an emergency, and they are typically available for sub 150.
 
mrblaine said:
As stated previous, I ran this by my gas guru, my physics professor with a PHD, and my engineering mentor and they asked if you could provide some sort of reference they could peruse to help them with their understanding of the multi molecular nature of a gas that precludes it from reacting according to The Ideal Gas Law. When they looked it up at my request just to verify that they hadn't missed anything, the explanation made no exceptions for Co2 or any other poly molecular gas.
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They got back to me with more info. I'll cut and paste the reply from the expert.


I've been looking at the ideal gas issue and technically there is no such thing as an ideal gas. But at low temperatures and pressures, most gasses will behave close enough to an ideal gas meaning PV=nRT applies. Low pressures seems to mean less than 2bar or about 30 psi.




For a non-ideal gas, the PV=nRT equation can be corrected with a compression factor “Z” as follows PV=ZnRT. This means that if we assume a constant volume, P is directly proportional to Z*T. Note that Z is not a constant and varies with temperature and pressure for each type of gas. The Compression factor for air between 15 and 72psi and -10 and 80F ranges from .9957-.9999. So you can probably tell right away that there is not much effect since .9957 is practically 1. The Compression factor for CO2 between 16 and 80psi and 32 and 80F ranges from .9895-.9981. notably different than air but still pretty close to 1. Attached is a rough calculation for the change in pressure vs temperature (~80F to -10F) using the compressibility factor for what I assume to be a typical tire volume. I think the end result as far as CO2 not being a true ideal gas is: “who cares” because the pressure difference is so small. Where tire inflated with an ideal gas would loose 5 psi going from 80F to -10F, a tire with CO2 would loose 4.988 psi (aka 5psi as read on any gauge).




What is really interesting is that since the compression factor is less than 1 in these ranges, the change in temperature has less effect on the change in pressure than an ideal gas would (again only slightly). And CO2 has the lowest compression factor of the common gasses (Perhaps a good selling point).
 
Thank you all for the information. I've been viewing this thread gathering some information to make a setup for my TJ. How do you store your tanks in your rigs? Do you have tank mounts, strapped down, or some other contraption?
 
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