The practical alternative to on-board air compressors.
Problems With On-board Air Compressors
These days, one of the required items on a fully-built 4x4 is an on-board air compressor. Besides being able to air up your tires, it can also seat beads, inflate mattresses & rafts, and even drive air tools. Best of all, they're cheap and will never run out of air.
It sounds great but it's about as accurate as an auto maker's fuel economy figures: your mileage may vary. While some people may experience all the good points of an on-board compressor, the fact is that many don't.
To begin with, installation on some vehicles can be a breeze while on others, it's a real headache. Factory brackets for Jeep YJs are rare and won't let you use an a/c pump with a separate oil sump. Toyota & Nissan trucks have very litte room to install an a/c pump and its ancillary plumbing. And what do you do with a vehicle that already has a/c? Then there's the issue of finding a safe air tank and a suitable mounting location. After all that work, your total cost, including all hoses, gauges, filters, switches and fittings can easily exceed CAD$200.
Even after the installation, the risk of the compressor or its associated switches failing is quite high. The compressors used in these setups are usually old and unable to run reliably without some kind of lubricant (eg: refrigerant oil). Pressure switches, oil drippers and filters often can't handle the harsh operating conditions of a 4x4's engine compartment.
On top of all that, you have to contend with the space limitations of fitting an air tank to your 4x4 without losing too much cargo capacity. Most tanks I've seen just don't have the volume to properly re-seat the bead of a large tire. That's why you still see guys with on-board air nervously igniting ether-filled tires. Their tanks just can't provide enough air.
After all those negatives, you probably think I'm against on-board air compressors but I'm not. I just wanted to point out that installing a reliable compressor setup is not as cheap or easy as you might think. A properly installed air compressor setup is a wonder to behold. You will forever be thankful for spending the money on such a reliable and useful upgrade. But if you cut corners and try to cheap-out on the installation, you will be cursed with problems. And that brings me to the Powertank CO2 system. It's a different approach to providing an on-board air supply. Installation is a non-issue and consistency of operation is virtually guaranteed.
The Powertank Solution
Powertank provides an on-board air system by utilizing a tank of highly compressed CO2 (carbon dioxide) instead of an engine-driven air compressor. The sysem's main advantage, its CO2 tank, is also its only disadvantage. It cannot be re-filled on the trail or at home. It has to be re-filled at a welding supply or fire extinguisher store. Locally, the cost for this is around CAD$20 and in the US, the price is around US$9. This may seem like a big disadvantage but it's not. The Powertank PT-10 system we tested came with a 10-lb tank. This tank had enough capacity to air up 39 33x12.5" tires from 10 psi to 20 psi. That means that you would need to re-fill it about once every 9 trips. When you consider its advantages over an on-board compressor, you'll see that re-filling the tank is a small price to pay for its versatility.
The PT-10 tank with the supplied hose and optional mounting bracket.
We replaced the air chuck that comes with the hose with another quick-disconnect
fitting.
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The upper gauge measures tank pressure, the lower measures the output regulator
pressure.
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The tank's pressure should stay between 500 and 1000 psi under all
normal operating conditions. Output pressure can be adjusted from 0 to 140 psi.
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For starters, no matter what kind of on-board air system you have, it cannot compare to the Powertank's combination of portablity and capacity. If you have more than one 4x4, then the Powertank is by far the best air supply system for your needs. It is small enough to fit into any 4x4 and is fully self-contained so you don't need to route hose, hook up wires or install a compressor. Its portability also comes in handy when you're on a narrow trail and someone else in your group needs air. The system goes where it's needed, not your truck.
In case you're wondering, the tank uses liquid CO2 (carbon dioxide) instead of compressed air because the CO2 stores 20 times more energy. This huge amount of energy gives it the ability to easily re-seat the bead on a tire while it's still on the vehicle. If you've got a Powertank, there is no need to use ether. All that energy also makes it ideal for powering air tools. The PT-10 can provide about 20 minutes of continuous air tool power. Since most air tools are used for short periods of time, this stretches out to several hours.
I strongly recommend that you order the optional mounting bracket, as shown here.
It holds the tank nice and tight so it's protected from flying around in the
event of a roll over. Unhooking the tank when you need it is a breeze.
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The bracket has several mounting holes already pre-drilled so it should be
a painless operation to install it on your 4x4.
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We mounted the Powertank in the back of Project YJ. We'll probably mount it
elsewhere once we build our new cargo rack for the back.
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To safely store all this energy, the tank is made from 6061-T6 aluminum. It has a maximum pressure rating of 3000+ psi which provides a generous margin of safety, considering that the CO2 pressure ranges from 500 to 1000 psi. Of course, that 3,000 psi would never be reached because the DOT-approved tank is also equipped with a safety pop-off valve. Pressure can be regulated from zero to 150 psi. The regulator and tank pressure gauges are surrounded by a 6061-T6 aluminum handle that also doubles as a nerf bar for the gauges. A quick-disconnect fitting provides the connection to the coiled hose which comes with an air chuck on the other end. The hose is made from a material that lets it remain flexible at low temperatures. This is important since the expanding CO2 can get pretty cold after extended use. Included with our PT-10 was an extremely stout mounting bracket that will easily secure the tank in the event of a roll-over. Every component in the Powertank kit reflected a high degree of quality.
Impressions
Having entirely too much time on my hands, I decided to test the Powertank by completely deflating one of the 35x12.5" Pro Comp MT tires on Project YJ. To break the bead, I had to remove the tire from the vehicle and used the Tyrepliers. With the bead broken, I proceeded to inflate the tire with a blower attachment, the valve core removed from the stem, and the pressure regulator set to 150 psi. Within seconds, I had the tire fully seated on the rim. To see just how fast it could air up a flat tire, I pulled the valve core and let a tire go completely flat. Using the blower attachment, I re-filled it till it was around 10 or 15 psi. You can see the results by clicking on the following video links in either AVI or RealMedia formats.
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4.7MB
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189K
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| Seating a bead |
Airing up a completely flat tire to 15 psi |
My informal testing indicated that Powertank's table of air-up times was on the mark.
| Tire Size |
Starting Pressure |
To 20 p.s.i. |
To 30 p.s.i. |
| 31x10.5x15 |
10 p.s.i. |
21 seconds |
42 seconds |
| 33x12.5x15 |
10 p.s.i. |
30 seconds |
60 seconds |
| 35x12.5x18 |
10 p.s.i. |
40 seconds |
70 seconds |
Summary
The Powertank addresses all the weak points of an on-board air compressor and is an ideal on-board air system, as long as you don't mind having to re-fill the tank at your local welding supply, carbonated drink dispenser, or fire extinguisher supply shop.
(Powertank will be releasing a newer version of their kit that includes everything except the tank for those of us who find it easier to exchange CO2 tanks rather than get them re-charged. They also have a Jeep roll-bar mount which we're going to have a look at. It will allow us to mount the tank in a location which isn't currently utilized.)
...lars
