For awhile now, I've been thinking about buying a CO2 tank so that I could create my own carbonated drinks... The ability to use it to quickly inflate the tires on my XJ and my plane without having to use a 12V compressor was definitely a potential bonus... Previously, I had used a BBQ propane tank that I had converted for air storage and I would fill it up from my home compressor before taking my XJ out or before heading down to the airport (my plane has a very slow leak in the tires)... Unfortunately, a BBQ propane tank just doesn't hold that much air although you could pump it up to 300 psi if you had a compressor that went that high... Although it would be possible to fill the tires with propane, running air tools off of propane would likely be rather hazardous, so I finally broke down and decided to go the CO2 route...
I went to a local beverage equipment supply company and picked up a 0-160 psi CO2 regulator for $45... The outlet fitting used a 1/4" NPT thread, so I replaced it with a 90 degree street elbow and air tool quick connect fitting so that I could reuse my existing hoses and air tools... I stopped off at a local welding gas supply store and was able to get a brand new steel 20# CO2 cylinder for $95 which included 20# of gas... There was also a local company that had new 20# aluminum cylinders for sell for $100, but that didn't include the CO2, but it did include a handle / valve guard... At that point, I had a portable CO2 tank that could either run air tools or fill tires... Total cost, including the fittings, approximately $145...
The Power Tank systems are available in 10# and 15# tanks... Considering the fact that the cost to refill a 20# tank is basically the same as it is to refill at 10# or 15# tank, it is more economical to go the 20# route, although the tank does take up a little more room... The tank is a little shorter than a typical AL80 scuba tank and 8" in diameter instead of
7.25"... The gas capacity of 20# of CO2 is around 171 cu-ft -- twice what basically the same size in a scuba tank would be in addition to having the added advantage of being able to make carbonated drinks...There are some fixed 150 psi regulators available that are more compact and less likely to be damaged if you were to drop the tank on its side, but since most air tools require less than that, I would still have had to put an air tool regulator on the line to reduce the pressure to something more acceptable... Since I was going to be using the tank for soft drink carbonation also, being able to adjust the pressure at the tank was rather desireable...
Ok, now for the drink carbonation... First, I went to Pep Boys and bought four metal schraeder type valves that are normally used for wheels... I removed the black rubber washers from it since they would have imparted a tire store smell / taste to the drinks (this is the same reason that you would not want to use the rubber tire stems)... I then picked up some O-rings from the faucet section of my local home improvement store (Lowes)... I took a 2-liter bottle cap, drilled a hole in the top to match the size of the metal valve stem, inserted it from the bottom of the cap along with the O-ring and put the washer and nut on the outside of the bottle cap... I then filled up the bottle to within 2-3" of the top with cold water, put the top on loosely, squeezed the bottle so that all the air was out of it, and then inflated it to 40 psi... I then shook the bottle up for awhile and it was quite noticeable that the water was absorbing the CO2 since I could feel the pressure in the bottle decreasing... I added some more CO2 without opening the top, shook it up more until the pressure had noticeably decreased, and then repeated this process one more time... I then removed the top and had a nice cold glass of carbonated / seltzer water... Total time to make the bottle of carbonated water -- approximately a minute... Cost -- probably less than $0.05... Since this time, I have experimented with other drinks... I've made carbonated sugar free Kool-Aid for my daughter's lunch... I've found that Dr. Pepper is really sweeter than I prefer and diluting it by 50% with carbonated water is quite acceptable... I've tried carbonated chocolate milk -- I'm not sure that I like this one though since the carbonic acid that is created when water is carbonated tends to alter the taste of the milk to the point where it is somewhat 'different'... Probably one of those tastes that you just "have to get used to"... Perhaps more sugar in the drink would offset the taste somewhat... Next experiment will be carbonated sweetened ice tea and perhaps a carbonated cafe mocha type of drink... Haven't tried direct carbonation of alcohol yet though... Total additional cost of four schraeder type fittings and a box of O-rings, approximately $10...
Now that I have the CO2 tank, I guess I'm going to have to get into MIG welding so that I can use it as a shielding gas...
BTW, before I tried carbonating drinks, I tried oxygenating them by putting a quick connect air tool fitting on my O2 welding regulator... Although it is possible to get the drink to absorb the O2 and be somewhat bubbly, it's a lighter bubbly than carbonation and doesn't have the same flavor (due to the carbonic acid that is formed during carbonation)... The O2 also comes out of solution with the beverage more readily, thus you need to drink the beverage more quickly before it goes 'flat'... An interesting experiment, but not one that I would deem worth repeating...