Pics are up!
Comments... suggestions??

 

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.

 

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.

 

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.

 

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!

 

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?

 

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.

 

 

Dam your right... I can't remember who I heard that false information from. The phase diagram is quite convincing.
PV=nRT was pretty useful in high school chem

 

To digress further. What happens to the line at 31C and 72.8atm?

 

The big bang, only in reverse. I critically hope it never gets to that point.

 

Hey-oh. Bellydoc, when you are talking about all your welding and what not in your build up thread i tend to sometimes get lost. But as soon as you bring in physics and chemistry (and perhaps thermo) i am right with you.
Triple points and phase diagrams... look at you go!

 

The term at that point is "supercritical" liquid, which just means "above the critical point". I understand that it has odd properties up there, but nothing about it can either be applied to my project in the garage, or be fixed with sutures and antibiotics... therefore my understanding becomes cartoonish and secondhand.

 

i thought I was done with chem class.......

 

OK--

You guys are a wealth of knowledge. I guess what I'm understanding in lay terms---if you don't overfill the tank, it should be safe inside the FJ as long as the overflow valve is pointed toward the rear.

:cheers:

 

The pop off valve that's likely to blow is on the regulator. Unless you're using the CO2 tank to run an onboard air system with an ARB air locker installed, there's no reason for you to be driving around with the tank valve open.

The tank with a closed valve will handle the CO2 just fine. The tank is hydrostatically tested to a pressure in excess of 2500 psi. The CO2 fill is around 1000 psi. If you burp liquid CO2 into the regulator, though, it will decompress to a pressure below the phase change line in the phase diagram. It will evolve into gas and blow the pop off valve on the regulator.

There *IS* a pop off on the tank valve, but it's set for a much much higher pressure. Instead of protecting the regulator, it's protecting the tank. I suppose it's possible to blow this valve with CO2, and if it's possible, then it's happened... but that's not the typical CO2 incident. The typical incident is with the regulator pop off.

I had a crappy CO2 regulator on a welding bottle for a while, and if I did enough continuous weld, the regulator would freeze open. When I took my finger off the trigger, the downstream pressure would mount rapidly and the pop off would go. Then I'd have to shut off the flow at the tank or lose all my gas... and then wait for it to thaw.

 

Was the tank overfilled Tomas?
I have ran Powertanks since around '99 or so, and have never had the safety ring pop on me.

And my tank sits out in the heat of the sun when in the rig too.

 

The tank is behind the Scorpion Rack so even if a pressure plug blows, the most it will do is bounce off the rack or the back of the seat.


When I had a 10 lbs tank mounted (I still have the tank but use a 20 lbs tank now) on the side the way Layon has it, I put some wide 3M non-skid tape on the top of the plastic ledge to (1) protect the plastic and (2) help keep the bottom of the tank from "scooting" in small directions on the plastic while I was bouncing over rocks and rough roads.

Even though there isn't a tank there anymore, you can see the non-skid in the photo above.

 

I don't know if my tank was over filled. When the tank went it was a deafening noise. Had I been driving at the time who knows what would have happened. W5WI was also there when it went and he can attest to the sound.

 

I had a tank valve go once and can attest to the sound. Mine was on a roof rack mount at the time so it wasn't inside the FJ. I heard it go when I was inside the house (it was that loud). I called the PowerTank people and asked WTF? It wasn't hot outside and I had used the tank so the pressure was somewhere around 2/3 fill. They said that sometimes the pressure release valves just blow and there's no accounting.

 

Several years ago a friend of mine with a Landcruiser 80 series told me a story.
His tank had been topped off to much, and he kept it in the rear like I do.

From an October Fall Colors run on the Naches trail back in 2000.

He was in the grocery store with his dog in the rig.
He came back out to put the groceries in, and his big dog had crapped all over the rear seat.
The valve thing popped, and literally scared the crap out of his dog.

 

He was in the grocery store with his dog in the rig.
He came back out to put the groceries in, and his big dog had crapped all over the rear seat.
The valve thing popped, and literally scared the crap out of his dog.

haha poor dog. I am sure in an encosed area his ears were most certainly damaged.

Is there any way of preventing this? This would seem like it would be a very very dangerous hazard if happening on the road.

 

Bump for great idea! I'll be stealing layonnn's idea. :cheers:

 

Ha,no worries. This setup also allows for a great way to mount a Molle bag or a fire extinguisher next to the tank.

 

I've been using this idea for a while now. Layonn deserves some credit for a great idea. Soon I'll be drilling the mount for my 5# backup tank.

 

thanks crestwood. I now have my fire extinguisher mounted up next to it. All i did for this was use a super quickfist, drilled three holes and pow, fire extinguisher mount.

 

Thanks for the input and the pics Layonnn!

I was thinking about drilling some holes out in the bracket, but I didn't know how others had done it. I'm thinking about raising the bottom off of the wheel well with some rubber stoppers to level it out.

Any suggestions or hints? Thanks! :bigthumb:

 

since the fender is at a sort of slant, if you level the base, there is a gap from the end of the base of the bracket to the fender. I preferred it to be more of a flush fit. Between the base and the plastic fender, i have large rubber washer though. And then between the tank and the base i have some grey anti-fatigue matting cut to shape to prevent metal on metal clanking.

The tank also works well to retain stuff up in that little port hole of a window. I keep a fleece blanket and my rain jacket there bundled up. You are never going to need to see out of it anyway so whatevs. I may make a little bungie net thing to go right there in the future, if i find a clean way to mount it.

 

is co2 safe in the heat? you know living in AZ heat a car can get up to 130 degrees....I know if you leave any pressured containers such as hair spray etc..under pressure items for the day and come back it will explode......

 

There are lots of people using these that live there without any issues. I would keep a window cracked if i knew it was gonna get that hot though.

 

check my build thread....I got some flat bar from tractor supply.....cut it to length. Then mounted CO2 rack to the flat bar and got longer bolts to mount where the two hooks were before on driver side back there.

put some foam rubber on bottom of bottle rack to help give some support and cushion the jouncing from trail. No heat issues yet and has been in there for a few months now.
I put a beanie (cold weather cap) over the regulator and valve when not using in case it blows the safety valve to keep the insides contained a little bit....I hope. LOL