Looking into on-board air over the winter...

Curious if anyone has tried using a scuba tank for storage.. Though I have a few large cylinders, I also have a small redundant air system using what is called a "pony" tank. It looks just like a larger steel tank, but in miniature. I don't remember the size but I think it holds 20 cu ft of air. The first stage of the regulator has a low pressure hose that is typically used to inflate the buoyancy vest, but could probably be converted to a inflator chuck.

The question is... what volume of air would be needed to top-off four 33's dropped to say.. 15 psi? Can a 20 cu ft tank be sufficient?

 

Well, it would depend on how much the pony tank is pressurized, wouldn't it?

If you ignore temperature differences, and denote P for pressure and V for volume, you get P(tank)*V(tank) = P(tire)*V(tire) -- and I guess here the P(tire) would be the pressure increment you want to top off the tire with.

Note that your "20 cu ft of air" is not the volume of the tank (that'd be a pretty big scuba tank) but what the contents decompress to at sea level. In that equality, the Vs are the physical volumes of the tank and the tire. (Look up "torus" on Wikipedia for a reasonable approximation of the tire's volume, I guess.) HPH

 

I deal with SCBA's (what firefighters use) on a daily basis. I've looked into this pretty closely.

Your 20 cubic foot pont bottle would give you the equivalent amount of stored air as 6 or 7 minutes of a good quality compressor running (at +/- 3 CFM). That might be enough to top up your tires, but probably won't get you from wheeling pressure all the way up to highway pressure. Also, it doesn't provide any "spare" air. If you lose a bead, you've got enough air to re-seat it....but not enough to re-inflate at the trail head afterwards.

The tanks that you see most people running on their Jeeps and off-road rigs are CO2 tanks - and CO2 has a BIG advantage over air for this application. Once you get it under enough pressure, it liquefies, meaning that you can store a lot of compressed CO2 in a relatively compact cylinder without having a ridiculously high pressure.

 

Hmm... that's not good. I don't like the idea not having some back-up.. seems to defeat the purpose.

I looked into the Co2 but the hassle with refilling is more than I want to deal with. Running air tools would be awesome, but I am not that far from home and rarely will there not be some people nearby.

I believe I have a steel 19.

I have 33's.. doubt that makes THAT much of a difference.. I still don't like the idea that I would be going so close to the limit of reserve air and for the price, I think the ARB or VIAIR systems are a better option.

It was an ideal worth examining.

 

Tie 'em down, knock off those valves ... and you've got yourself quite a rocket boost there. HPH

 

I just bought a VIAIR 400 portable compressor for my dad's birthday. I must say its a very nice piece. I cant remember the exact numbers off hand but I think it will fill up a 33" tire from 15psi- to 30 in 1 minute 30 seconds ( if i recall correctly). It comes with a travel bag that you can just toss in your trunk and take anywhere with you. I would highly recommend one.

 

thanks..

My next step was to look at portable versus hard install..

 

What's the life of something like the viair? I haven't owned any of these more expensive compressors but the cheaper ones don't last long.

 

I'm carrying one of these filled w/ co2:

http://www.***************.com/shop/...m-p-16503.html

I wanted something fairly small that would stay in the Jeep all the time; mine's a daily driver.

Probably not big enough for long off road trips though w/ lots of airing up and down.

Supposedly co2 tanks are safer? Supposedly they don't turn into missles if the valve is broke off? I think that's what Powertank's site says anyway.