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Discussion Starter #1
Hi guys,

What do you think about on-board air tanks? I would like to get some air on board either via a compressor or an air tank. So far it appears that the second approach is what I want because I'll be able to transfer the tank from one car to another if needed. The 15# setup will cost me anywhere from $400+ and up. The only downturn is getting CO2... It should cost me about $20 per fill up.

On the plus side, a tank will allow me to run power tools and since I don't have a garage this is a big plus (I can do minor work in the driveway w/o having to ask the neighbor to run the cable for me). Anyway, questions or comments are welcome. Here is the product that I am looking at:

http://www.powertank.com/products/sfID1/13/productID/205

That is probably as large as I would want to go.
 

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but the final question is how fast does it fill said tires. i know for a fact that after the last wpaxc run, a guy (dana for all of u that know him) had all 4 of his tires filled and had his CO2 tank put away before Muzikman and myself had 2 of our tires done. i guess if u want to air up in absolutely no time what so ever then get the power tank. but if u dont really need to air up that quick then a small air compressor is definately the way to go. just my 2 cents...
 

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Discussion Starter #5
I had a small compressor as well. Some salt water got into it and the thing is gone (will be taking it apart to see what is happening. I guess the most attractive package here is that you can attach power tools to this thing and inflate fast. I have 265's and I don't think that I'll be going to 35" tires any time soon. With this in mind a 15# tank should lasts me for a long time.
 

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I was thinking of the arB onboard air...I was thinking to mount it in the engine bay, but wondering where? has anyone done this before...I would like to power some basic air tools with this compressor.
 

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if u really want to get a compressor that will work off of the engine, and u can live with out a/c, u can always drain all of ure a/c and use the compressor that is bolted to the engine to power tools or air up... lol but that is an extreme use for this... i know ive seen this done somewhere on line and they say it works really well. but i could just be blowing stuff out of my ***.
 

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Someone posted this under the same subject on another forum i frequent. This is just a cut and paste of someone elses take on this subject. Makes sense to me.


"lots and lots of guys really like CO2. i've seen it in action and it is pretty neat. a lot of it depends on your situation. if you plan on doing any kind of serious expedition or multi-day 4x4 stuff i personally wouldnt reccomend CO2, purely because i'm very much a fan of redundancy. i'd much rather have a permanent on board compressor and tank setup. i've heard of guys running air tools off CO2 but i've never personally dne it and i'm just not comfortable with the idea of a non-renewable tool like compressed air on the trail. the advantage also in favor of a compressor is if you ever decide to go with an air locker you're already setup with air. i'm not downing CO2 because as i said lots of guys swear by their CO2 tanks, jsut consider the pros and cons of both systems, on the upside for CO2 users, there is no need to worry about compressors overheating or tank leakage etc. you've got what you've got, and as i understand the CO2 tanks are deceptively high capacity. as far as cost is concerned, once you're out, you're out, AFAIK those tanks are somthing like 600psi, so you cant refill them yourself, but for a nominal cost a gas company can do it for you"
 

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Discussion Starter #9
Mcampana,

This answers my question very well. I believe that I fit in the category that can benefit from the tank as opposed to on-board air.

Thanks!
 

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I've used both, here are a few thoughts:

I picked up a 10 Lb CO2 system right after I got my truck a little over 2 years ago. It is great for airing up tires after a run, or topping them off in the driveway at home. The main reason I don't carry mine around as much now is the size and weight. It is a real pain to secure in the back, especially when I have a lot of other gear. I sleep in the X, so if I'm camping that is one thing I would not want to leave on the ground under the truck at night. A 10 Lb tank really weighs in at over 27 pounds when full with the regulator. You have to also remember to weigh it periodically, as that is the only way to tell how much CO2 you have left. The gauge only shows gas pressure, which is pretty much constant until the tank is empty. I have not tried running air tools, but I've heard that they work well. Keep in mind you also can't "top off" a CO2 tank, it has to be vented then refilled completely. If you've got 1/2 tank and are leaving on a long trip you either take only 1/2 tank or lose that 1/2 and pay for a full fill, or have a spare tank to rotate.

I now use mostly a Viair 440P compressor (the portable one with the handle on top). It has worked very well, and takes up a lot less space. It does take a lot longer to air up, and does require attaching the wires to the battery etc. I also have a little $50 Q-something from Costco that also works well, just about as fast as the Viair, but nowhere near as well built. I keep it as a spare since it is so small.

I would think that a 15 Lb CO2 tank system would be too big and heavy. There is no place to attach a mounting bracket to in the back of the X without doing some reinforcing behind the plastic panels, even for a 10 Lb tank. By the way, the brackets are pretty heavy too.

For the money you could try to find a place to rig up the Viair On-Board Air system, with a 400 or 450 series compressor and small tank. Some of the folks at SCCX have those, they work great for air tools. One of the 2 I'm thinking of has the system mounted up inside his rear Shrock bumper, the other has it in a tool box in the back of her Frontier. I'm trying to figure out a place to mount one without having a Shrock rear bumper. There is not enough room under the X with the spare tire and tow hitch in place. Now I thinking of a sort of modular thing that I attach to the roof rack and run the power cord only when needed. I would only use it when stopped so all I need is some sort of protective box that also ventilates.
 

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You also have to look at the property of gas between compressed air and CO2. Personally, on a daily driver I would not run CO2. The pressure in the tires will fluctuate more than with air. On a trail rig (or trail tires) CO2 is fine IMO.

Also, if you live where it is cold, CO2 is not the best solution. The reg and lines will freeze up real quick. You will need to keep the tank, reg and line warm while using it.

You can run air tools off CO2, no problem, but I would not make it a common habit. The problem is not only is CO2 cold when it's released, it's also a dry gas. You need to keep the tools well oiled (more than twice the normal amount) and if you see frost forming on the line close to the tool, discontinue use until it warms up. The cold will destroy the seals in the air tool.

CO2 is fast at filling up, at room temp the pressure in the tank is about 800psi, you regulate that down to 100psi, that means you have quite a bit of pressure. Also, since it's stored as a liquid and then vaporizes to a gas, this means a rather small tank can produce a lot of gas. But again, depending on the temp will depend on the pressure.

Also, keep in mind, although CO2 is safe if handled properly, if handled improperly it can be deadly. That tank has to be securely attached and a guard needs to be placed around the valve/regulator. If that valve/regulator is compromised, the tank will take off like a rocket.

Here is a graph that might help to explain how CO2 is effected by temperature.
 

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Powertank is overpriced, try Ultimate Air... I have the 15# unit with the adjustable regulator and I love it.
 

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Muzikman said:
... a guard needs to be placed around the valve/regulator. If that valve/regulator is compromised, the tank will take off like a rocket ...
I'm sure some of you have seen it, but there was a Mythbusters episode where they actually tested this. They took a CO2 tank (I think it was CO2, it may have even been a Scuba tank), pointed it at a cinder block wall and knocked off the regulator using a guillotine-type contraption. The thing put a neat hole the exact size of the tank all the way through the wall. Some web searching would probably turn up the video. The point, though, is that I don't think I'd ever run an un-secured CO2 tank ... but I can see the attraction of the system, in principle.

-Jonathan
 

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Muzikman said:
Also, keep in mind, although CO2 is safe if handled properly, if handled improperly it can be deadly. That tank has to be securely attached and a guard needs to be placed around the valve/regulator. If that valve/regulator is compromised, the tank will take off like a rocket.
Umm... Here's something I copied and pasted from the Powertank website;

Q: “How safe is a tank of compressed CO2 in a vehicle?�

A: The Power TankTM uses liquid CO2 gas which is an inert, non-toxic, non-corrosive, non-flammable gas. Our aluminum tanks are D.O.T. (Dept. of Transportation) approved. CO2 goes through a phase change from liquid to vapor as it releases its energy. This evaporative process slows the pressure release rate meaning that a CO2 tank will not become a high speed rocket like a scuba tank would in the rare event of a valve decapitation. A Power Tank is as safe as a CO2 fire extinguisher.


There are certainly a lot of pros and cons to each setup. Personally, I'm a big fan of the portability of the C02 tanks. It's very easy to remove the bottle to go work on someone else's rig, whether you're at a trail staging area or working in a friend's garage who doesn't have an air compressor.

Someone commented that the brackets for the Powertanks are very heavy. Not all of them. The Powertank "Super Bracket" that comes with a lot of the bottle packages is made out of 1/8 Aluminum and is EXTREMELY lightweight. That's what I have mounted to the body sheet metal in my rear storage area.



Also, I haven't done much research on the on-board (compressor + tank) air systems, but how many of them have the storage and outlet pressure capability (200 psi) to re-seat a tire? That *might* be +1 for the C02 tanks, set up with a capable regulator, of course.
 

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skibum315 said:
I'm sure some of you have seen it, but there was a Mythbusters episode where they actually tested this. They took a CO2 tank (I think it was CO2, it may have even been a Scuba tank)
I saw that episode. It was a scuba tank. No need to stress about having your C02 bottle turn into rocket...
 

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mcampana said:
So how many times can you fill up all four tires before you need to refill the co2 tanks?
There are a lot of variables in that question. Tank size, tire size, how much you need to add to the tire, etc. I'm sure I'm starting to sound like a Powertank sales wh0re, but here's another chart from their website that might help you out.

http://www.powertank.com/full.chart.html
 

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OregonX said:
I saw that episode. It was a scuba tank. No need to stress about having your C02 bottle turn into rocket...
Good to know, esp. considering your previous post ... thanks for the info. :salute:

-Jonathan
 

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A CO2 tank can and will become a rocket. Yes, a dive tank is worse because of the extremely high pressure, but if you loose a valve from a CO2 there IS enough pressure for it to take off. Ask me how I know, I have done it and I have seen it.

Now, what does happen is as the CO2 is released rapidly it will chill. This in turn eats a lot of the energy. But, many people leave the tanks in their vehicle in the summer which will raise the internal pressure up over 1200psi. At that pressure, even if the tank chills, it will still take off.

http://www.paintballstar.com/pn/modules.php?op=modload&name=PagEd&file=index&topic_id=21&page_id=130

Now, it's a much smaller tank, but at the same time, it's a lot less CO2.
 
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