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  • CO2=Convenient Onboard Air

    Well, it's been posted a million-times before on the Web, but I thought I'd just chronicle my OBA setup. I did not have the time nor the inclination to go rummaging through the pick-n-pull for a York AC compressor to get OBA.

    Admittedly, Kilby Enterprises makes it easy to order everything including the York compressor online, but I was far too cheap and lazy to even go that route. I reasoned that eventually the Missus would get a Jeep and need OBA, so why fix it to one vehicle?

    Installing an electric compressor was also a consideration, but the price was again an issue and I'd still have to pop the hood and route all that wiring. Furthermore, although there are portable compressors that can be moved from truck to truck, I was concerned about duty cycles and having to let the thing cool off between long inflation sessions.

    PowerTank looked pretty cool, easy, mobile and maintenance free. Again, my skinflint persona could not swallow the $390+ price tag I also reasoned that I would not be needing low-pressure CO2 output as I would not be:
    1. Using CO2 as a shielding gas for welding
    2. Keeping a beer keg pressurized
    3. Using airtools that I care about (thank you Harbor Freight)


    So, I got my lazy butt off the couch and pieced together the poor man's Power Tank.

    Fixed output CO2 regulator from William's Balloons. This is the heart of the system.

    My recommendation is to get the 150 female regulator. The 150's are finger tightened, while the 103's are wrench-tightened and require a fiber disc washer. The female is better for when the coupler snaps off because you dropped your tank, you can just drill it out of the female socket. I went with the 150 PSI regulator, but if you plan to use airtools you care about get the 120 psi regulator which should bring pressure down to 100-120 psi.

    Don't forget to ask for the Jeep club discount. I said my club was the My Jeep Rocks Club out of Southern California. Cost $36.49

    Next, had to get a cylinder. I knew I wanted something with a handle to protect the valve and facilitate carrying it around. I chose the same size as the most common PowerTank, 10#. I also chose aluminum over steel, because of the weight savings. My tank looks like this .

    BeverageFactory.com sells these cylinders for $84 plus shipping (they are out of San Diego). Unfortunately, they have to ship empty which means another trip to get it filled.

    Well, being the lazy butt, I just called AirGas and found their nearest location. I was delighted to learn that they had just come into a new shipment of 10# aluminum cylinders with handles. Cost $95 including the first fill

    Now, if you are feeling really cheap or sneaky, you can pay a nominal deposit and get a heavy crappy beat-up steel tank and just exchange it for another heavy crappy beater cylinder when it's empty. Just pay for the fill and get your empty cylinder swapped. Now, if you are sneaky or friendly, you may be able to talk the attendant into getting you the nicest looking tank they have, sometimes they have aluminum cylinders in the pre-filled stands. If you get a nice aluminum cylinder, bonus! Eat the deposit, paint your name on it and get it refilled while you wait.

    A few things about buying used cylinders, they have to be hydrostatically checked every 5 years. Once it passes test, the cylinder gets the test date stamped on it. No cylinder will be filled with an expired test date, so think about that when you go fishing around the flea market for a cylinder. Also, you need a CGA-320 Valve on the cylinder otherwise your CO2 regulator won't fit and it won't be filled by the attendant.

    OK, full tank and regulator in hand, I went to every cheapskate's favorite tool store, Harbor Freight. There I picked up:
    25' 300psi hose. Cost $8
    Two quick release couplers and a fistful of couplers for the hose and tools Cost $5
    1/2" drive air impact wrench (already had set of 3/8" sockets and 1/2" to 3/8" adaptor) Cost Easily the best $15 I ever spent on my Jeep!

    On the way home picked up a tire inflator from PepBoys with an integrated 0-60 psi guage. Cost $15

    I used tie-down straps and bungees to strap it down to the floor of the Jeep until I had a horrible vision of a 25# metal cylinder squashing my skull like a ripe tomato. I ponied up for the PowerTank mounting bracket. Cost $50

    The most expensive item after the cylinder was the bracket. You may be able to fab up something on your own or perhaps hunt around a fire extinguisher/welding/scuba store and see if you can get a bracket that costs less than a Ulysses S. Grant.

    Total cost $224.49

    For this paltry sum, I did not have to lift a single wrench to get on-board air and now thanks to my air wrench I was able to install my front bumper and rollcage extension in a few hours! See what you can expect from your 10# cylinder.

    Hope you found this write-up useful and inspires you to get on-board air in your Jeep!
    Last edited by jmbrowning; 09-13-04, 09:44 PM. Reason: Updated Williams Balloons link
    Quis custodiet ipsos custodes?
    2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

  • #2
    AWESOME write up!

    hehehe...I loved it

    How often do you have to fill that tank? What does it cost to refill? I suppose that the refill would be dependant on how often you went wheeling...so I guess the question would be, how many wheeling trips do you get out of this setup, before returning for a refill?

    Tam
    2002 TJ on 35s a bit of lift with some stuff
    Rock-ItMan all the way around

    Comment


    • #3
      Cost of ownership

      Well, the fills are about $10-$20 depending on where you go. Welding shops tend to cost a bit more. Fire extinguisher shops if you can find one are a bit cheaper. I go to AirGas and spend about $15 bucks.

      How many tires can you air up on a cylinder? Hard to say, because I never just use a cylinder for airing up tires. I am constantly using it for the air wrench. Estimates on the web say about 16 35" tires from 9 psi to 28 psi. I'd say this is about right.

      If you air down less (~12-15 psi), you will get dramatically more tires in as the pressure-volume curve is pretty flat until you get to around 25 psi (lots of gas to get little psi increase). After 25 psi, the curve gets more vertical (less volume needed to increase psi).

      The CO2 tank is FAST. My fills on 12-15 psi (16" rims) to 35 psi take a little less than a minute. I think my little tank is probably faster than the gas station. Definitely faster than my friend who was running his ARB locker compressor to air up his 35's to 22 psi and driving REALLY slowly to the gas station.

      I like my CO2 setup so much I might just pay the $75 deposit and just get a beater CO2 tank for around garage use and save the aluminum cylinder for off-road use only. I always weigh the cylinder before I go out. Cylinder tares weight is ~14.5 pounds so 26 pounds is pretty close to full. I also weigh after filling to prevent an overfill/burst disc situation. Haven't had a tank too heavy after a fill yet.
      Quis custodiet ipsos custodes?
      2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

      Comment


      • #4
        Great ideas....thanks for the links.
        Insert witty comment here.

        Comment


        • #5
          Williams Balloons & Helium, Santa Maria, 1-800-235-4112
          Damn domain name squatters...
          Quis custodiet ipsos custodes?
          2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

          Comment


          • #6
            Looking at the mount then turning my head to look at the extinguisher mount on the back of the fire engine, then back at the CO2 mount, I see that they are exactly the same mount. Searching the internet has yielded only a reduction of about $12 for the mount, but I know we bought them for about $25. If someone were really interested in this they could do more shopping, perhaps visit an emergency supply business and save themselves the 25 bones + shipping.
            I'm a Daddy!!

            [COLOR=DarkRed] Rear bumper/tire carrier and front bumper!![/COLOR]

            2002 Jeep TJ (Ember)
            1982 Jeep J10 w/ a 360

            Comment


            • #7
              That's great info. I never thought about going to a fire engine boneyard or EMS supply company. I have a neighbor who bought a LAFD truck in NH and is restoring it. I'll have to give him a jingle about it.
              Quis custodiet ipsos custodes?
              2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

              Comment


              • #8
                I myself contemplated on getting the Kilby OBA but just couldnt justify spending so much for the amount of offroading i do.

                I'll just go with PowerTanks CO2 tank for now.

                BTW are Powertanks bottles aluminum or steel?

                Comment


                • #9
                  Powertanks are aluminum.

                  Seriously consider building your own CO2 outfit if you aren't going to be running a lot of expensive airtools on it. Even, Powertank has recognized that most people just air up and have come out with the PowerShot regulator, which like the Williams regulator is not adjustable, but costs about $100 more

                  If you do get a CO2 tank, buy the widest diameter hose you can. I run 3/8" and it just seems to run faster and have less backpressure against the safety valve. The 1/4" hoses are just a bit too thin.
                  Quis custodiet ipsos custodes?
                  2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

                  Comment


                  • #10
                    Question on the powertanks: Any one know the limitations on heat for these tanks/regulators? Have an idea to mount, insulate/refrigerate a tank inside engine compartment dead space between my 2.4l and fan. Too dangerous?

                    Comment


                    • #11
                      Hey Ted, nice write up. I too went the CO2 route for many reasons and yes I'm too lazy to do all the plumbing... with the york. One thing your left off your list of task it can do (use mine for homebrew kegs too) was a Locker. I use mine to run the ARB in the rear too. Powertank make a nice manifold set up for this purpose.

                      Cheers, Tom

                      Comment


                      • #12
                        Originally posted by MoBjeep View Post
                        Question on the powertanks: Any one know the limitations on heat for these tanks/regulators? Have an idea to mount, insulate/refrigerate a tank inside engine compartment dead space between my 2.4l and fan. Too dangerous?
                        CO2 tanks do best in dry warm environments due to issues of condensation and freezing of the regulator. The engine compartment is plenty warm enough to ensure a toasty nonfrozen regulator. The problem may be TOO much heat (see below).

                        The regulator MUST be above the tank. The tank must sit upright during use or the liquid CO2 will run out the regulator instead of the evaporated CO2 gas. This will result in an instantly frozen regulator and hose. Not good.

                        As far as how much heat can be taken before the thing blows the popoff valve, this probably has more to do with overfilling. Weigh your tank after the fill to ensure there is enough space for the CO2 to evaporate into without causing excessive pressure (pressure is inversely related to volume). There will be more heat in the engine compartments resulting in more evaporation and therefore more pressure per given volume. I'd suspect you'd blow your overpressure safety valve if you put the thing in your engine compartment.

                        Strongly suggest you either mount it behind your tailgate or behind the spare tire (or wherever you put your Jerry cans). There are still reports of safety valves blowing in hot desert weather when overfilled.
                        Quis custodiet ipsos custodes?
                        2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

                        Comment


                        • #13
                          I like the CO2 setup also....

                          But why, when I call around to find prices on tanks, all the guys are asking, or suggesting that I go w/ Nitrogen.
                          The CO2 setup last for more fills, right?

                          I've read research on the comparing of the two saying that there really is no pressure change, and if there was, it was only 1 pound.
                          But still to this day you will hear that "CO2 changes pressure with conditions".

                          What's the vote around here..I know Sandy uses CO2, and he filled my tires couple weeks back. I checked them when I got home, as a matter of fact, and no change..and it didn't seem to change before the next time I aired down, which was a week later.
                          So why are the racers so gun ho about Nitro?? Besides their shocks, why would they prefer it so much?
                          David aka Mr.[COLOR="DarkOrange"]Orange[/COLOR]
                          I think it's my turn for a bailout....what do you think?

                          Comment


                          • #14
                            Sometimes I am quite surprised that a thread can have legs that last almost four years, then I remember what a great website MJR is (thanks Sarah)!

                            The CO2 is a liquid which will expand to a considerably larger volume than a mere compressed gas. While you can't charge your shocks with it, it does make a nice shielding gas for your battery operated wire-feed welder.

                            The downside of course is that releasing all that carbon dioxide is supposed to be dissolving the ozone layer in the Antarctic and resulting in a skyrocketing incidence of melanoma in penguin species.
                            Quis custodiet ipsos custodes?
                            2003 TJ Rubicon: 4.5" OME coils; RE SF2; NthDegree TT/oilpan skid/shock shifters; FXD rock rails; Anti-Rock; 5150'

                            Comment


                            • #15
                              :geek: so that means that nitrogen is safer for the world?
                              David aka Mr.[COLOR="DarkOrange"]Orange[/COLOR]
                              I think it's my turn for a bailout....what do you think?

                              Comment

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