How to: Install CO2 tank in rear

layonnn · 05-03-2008, 08:14 PM

I picked this up via the group buy from trdparts4u, thanks for the deal Gerone.

The area above the rear tire well is prime real estate that i have been looking to put to use.
I had a long aluminum bar that i cut to 17 1/4" with a hack saw and then grinded the edges smooth. Making this bar took the longest time b/c of having to keep bolting it up, make some marks, drill, bolt it back up, etc.

I bought two longer M6 bolts to replace the factory one and mount the aluminum bar to which the tank bracket would be mounted to. I bought some rubber gaskets to place between the aluminum and tank bracket to prevent any metal on metal vibrating (noise). I used 14mm bolts to attach the bracket to the bar and the bracket to the wheel well. note: You may need to add a couple washers between the grocery hooks and the bar in order to allow room to get a wrench on the bolts that hold the tank bracket to the bar. I used two on each side for this.

Make sure when you mark your holes for the wheel well you check to see you are not too close to a rib underneath the plastic. Have enough distance to clear your washers.

After everything was bolted up and the tank was in place, i gave it a good shaking. Everything felt sturdy and nothing budged.

I had hoped this wouldn't be an issue, but it is. The tank now sits on the lower bolts attached to the bracket. I will have to make yet another trip to Lowe's for some rubber to place on the bottom of the bracket that will elevate the base above the bolt heads. I will just attach it with some 3m adhesive i have laying around.

layonnn · 05-03-2008, 11:46 PM

Pics are up!
Comments... suggestions??

**BellyDoc** · 05-04-2008, 12:22 AM

I'm glad to see that you've mounted this vertically.

Once in position, a mounted CO2 tank tempts us to use it by just hooking up a hose, and opening the tank valve.

If you mount it flat, this is a DISASTER waiting to happen.

If you open a tank valve on a CO2 bottle laying on it's side, it can blow superheated liquid CO2 into the regulator, where it will decompress into gas, explosively.
On the driver's side, the rear corner window is invisible to the driver from any angle, so having the bottle upright does little to alter your view.

Nice job.

An option, if you don't find a sheet of thick rubber that you like for elevating the base of the tank off those bolts, is to use rubber furniture feet. Many of these are supplied with an adhesive backing already in place. They're typically a semi soft rubber or synthetic polymer. You'd just need to find a type that's slightly taller than your bolt heads.

You may be able to improve the situation by lowering the bolt heads too. Unless the holes through which the bolts pass are very loose, you can dispense with the fender washers on the metal side. I'd say that having a washer on the plastic side might help distribute the clamping force, but this is a comparatively minor component of your bracket fixation. The crossbar part of your build is more than equal to the task of carrying the load by itself.

layonnn · 05-04-2008, 12:30 AM

I have those large metal washers on every side of the bolt and nuts just to be overkill.
I saw some of those furniture feet things today as i was looking for some bolts.

I did a little research on CO2 before i purchased this from trdparts4u. Apparently, the CO2 is in liquid form in the bottle at all but the top. The top is in gaseous form. So, if you lay it on your side (as i have seen some mount it) and use it, you will get the liquid form coming out. Probably gonna give you frostbite if it hits the skin.
Maybe in the future if i decide to get some airtools i will buy an adjustable regulator, for now, filling up the LTB's is all the tank will be used for.

**BellyDoc** · 05-04-2008, 12:45 AM

The only reason its in liquid form is that at about 1000 psi, even at room temperature, it's a liquid. However, once it gets through the regulator, it's exposed to room temperature at a maximum of about 125-140 psi. If liquid CO2 was allowed to push ahead through the regulator, it would evolve on the other side into a rapidly re-expanding gas. At a minimum, this would play havoc on the regulator, blowing out the pop-off valve and hissing uncontrollably. However, if it was to put liquid all the way into the hose, you'd have a bomb, by definition.

If it happened WHILE you were plugging a hose into a quick disconnect fitting... it could conceivably take some fingers off in the blast.

Radio · 05-04-2008, 01:19 AM

Good thing its not nitro glycerin!
Nice job mounting the tank, gives me a good idea for mounting mine, and it will look alot like yours!

**COOKN** · 05-04-2008, 08:06 AM

A friend of mine who does a lot of wheelin' in his jeep club had a tank install in the back of his jeep. The folks at the welding shop overfill his tank and his safety valve blew inside the jeep. Luckily the valve was pointed toward the rear of the jeep or it could have been disasterous. I'm sure this was a freak thing. But I'm not sure where else you would put it unless you had an equipment trailer for your FJ. There could be a problem w/ the trailer depending on your type of wheelin'.

layonnn · 05-04-2008, 08:29 PM

Quote:

COOKN previously said:

A friend of mine who does a lot of wheelin' in his jeep club had a tank install in the back of his jeep. The folks at the welding shop overfill his tank and his safety valve blew inside the jeep. Luckily the valve was pointed toward the rear of the jeep or it could have been disasterous. I'm sure this was a freak thing. But I'm not sure where else you would put it unless you had an equipment trailer for your FJ. There could be a problem w/ the trailer depending on your type of wheelin'.

Dang, that is some good info to know. Was it a power tank or The Source type or a generic beverage type of tank?

The Stig · 05-04-2008, 09:31 PM

In the peak of my paintballing days I had some CO2 tanks of mine overfilled on a hot day. We had left them in a parked car and when I came back I noticed a couple of them felt lighter than others. I didn't know why that was until I had later brought them up to my room and had a couple of them popped and start spewing CO2 into the room as I was sitting at my desk. It's actually in solid state when it's under pressure in a tank. ever played with dry ice? it's fun stuff.

It would be pretty nasty if you got enough solid CO2 into the tire to make it explode. You would prob have to try hard to screw up that badly though.

Nice mounting. Now you can take it of your "need:" list in your sig

**BellyDoc** · 05-04-2008, 11:16 PM

Quote:

The Stig previously said:

In the peak of my paintballing days I had some CO2 tanks of mine overfilled on a hot day. We had left them in a parked car and when I came back I noticed a couple of them felt lighter than others. I didn't know why that was until I had later brought them up to my room and had a couple of them popped and start spewing CO2 into the room as I was sitting at my desk. It's actually in solid state when it's under pressure in a tank. ever played with dry ice? it's fun stuff.

It would be pretty nasty if you got enough solid CO2 into the tire to make it explode. You would prob have to try hard to screw up that badly though.

Nice mounting. Now you can take it of your "need:" list in your sig

Not to digress into total nerd-hood... (ok...maybe a little) but it's NOT in a solid state. It's a liquid.

The property of a pure molecular substance like CO2 can be modelled using something called a "phase diagram". The diagram is a graph on which the X axis is temperature and the Y axis is pressure. At any given temperature and pressure, the substance is either in a gasseous, liquid or solid state.

At room temperature and one atmosphere of pressure, CO2 is a gas.

However, if you lower the temperature while maintaining one atmosphere, CO2 will coalesce into a solid at about -78 C. At increasing pressures, it will maintain the solid state at higher temperatures.

At 5.11 atmopheres, CO2 can achieve a liquid state at -56.6 C. In fact, solid, liquid and gasseous CO2 can co-exist at that temperature and pressure.

If you maintain room temperature but increase the pressure to something on the order of about 1000 psi, CO2 will coalesce into a liquid. This will be liquid CO2 at 27 degrees C.

The gas space over the liquid within the pressure cylinder will be at equalibrium. If you release some of the gas, then liquid CO2 will boil off into gas form until the pressure is again equalized. For this reason, the pressure inside a tank of CO2 remains the same until all the liquid is gone.

However, when the gas goes from room temperature at 1000 psi out into the atmosphere at 14.7 psi, the expansion dissipates heat, resulting in lower temperature.

The gas/liquid inside the tank isn't cold... but when it escapes and depressurizes, it acts just like a refrigerator coil. This is true of any gas or liquid that is released from pressure.

"PV=nRT" is the ideal gas law which describes this phenomenon. If P (pressure) on one side of the equation is suddenly reduced, then T (temperature) on the other side follows suit.