I do not have a very good understanding of air tools... but I do like the idea of having OBA... If I were to pair a 150 psi compressor with a 3 gallon air tank.... would this be enough to run and air impact gun?

3 gallons will run one.. But its going to run a lot..

so maybe a 5 gal?

Where are you going to put a 5 gallon in your X?
@ home 5 gallon min

i bolted a 5 gallon tank to the driver side rear wheel well in the cargo area, works out great

Send a message to TJTJ.. he mounted his underneath his X and has a ton of pics of it somewhere

Right on.. ill need to look this up... TJs pix never work

I do not have a very good understanding of air tools... but I do like the idea of having OBA... If I were to pair a 150 psi compressor with a 3 gallon air tank.... would this be enough to run and air impact gun?

The key question is not the size of the tank or the max psi...so much as the FLOW RATE, measured in cubic feet per minute (CFM).

Air tools use around 3-10 CFM, with ~6 CFM being fairly average.

Air tools also are limited to about 90 PSI, and you use a regulator to throttle the 150 psi in the tank down to 90 PSI at the hose.

Almost no typical 12 v compressors you'd mount in an X have an out put of 6 CFM at 90 psi.

Warn's PowerPlant puts out 5 CFM at 90 psi, which is very good, and is part of the winch.

Oasis and other ginormous 12 compressors costing over a thousand dollars can output maybe 8 -12 CFM at 90 psi though.

A Kilby, or other AC compressor powered system can also produce similar output, but require you to use a drive belt off your engine to drive it, etc.

For a typical OBA, the compressor alone will not keep up with air tools, you need a tank, and a regulator.

The flow rate of the compressor needs to be able to keep the tank charged long enough to cycle the air tool.

For an impact gun, say to do your lug nuts, you are spinning off a nut, and there's a lag before you do another one...which is a little time to charge the tank between nuts, etc.

For perspective.... 6 cubic feet of air is about 45 gallons.

For a flow of 6 CFM, that means in one minute, you'd use ~ 45 gallons of air....at 90 psi.

:D

So, what's in the 3 gal tank you wanted?

3 gallons of 150 PSI air - That's a charge of air that can allow about 12 gallons of air at 90 psi.

To last ONE MINUTE, you'd need 45 gallons of air....you have ~ 12 gal

That means you have about 16 seconds worth of 90 psi, 6 CFM flow, in your 3 gal tank.

How long to recharge it back to 150 psi?

That depends on the compressor's flow rate, and the duty cycle.

Typically, a few minutes to recharge the tank from 90 to 150 psi....to have another 16 seconds of bursts, etc.

The duty cycle of the compressor limits how long it can run, without needing a cooling off period.

If you have a 100% duty cycle compressor, you can run it for a decent amount of time, an hour or so without a break.

If you have a 30% duty cycle compressor, it may only be able to reliably run for 10 minutes, and then need to cool off for another 30 minutes, etc.

IE: A low duty cycle compressor will not stand a ghost of a chance to keep a tank charged while running air tools.


There are other things to consider for an OBA system...but the above is a good starting point at least.

:wink-big:

whoa... thanks for the info.... I know some people with mini trucks on air bags and I can get a deal on a small Viar compressor and a 3 gallons tank... but the viar is only a 30% duty cycle so thats not going to cut it....hmmm..... back to the drawing board! thanks again!!! What compressor do you have tj? also what do you typically use your OBA for?

The key question is not the size of the tank or the max psi...so much as the FLOW RATE, measured in cubic feet per minute (CFM).

Air tools use around 3-10 CFM, with ~6 CFM being fairly average.

Air tools also are limited to about 90 PSI, and you use a regulator to throttle the 150 psi in the tank down to 90 PSI at the hose.

Almost no typical 12 v compressors you'd mount in an X have an out put of 6 CFM at 90 psi.

Warn's PowerPlant puts out 5 CFM at 90 psi, which is very good, and is part of the winch.

Oasis and other ginormous 12 compressors costing over a thousand dollars can output maybe 8 -12 CFM at 90 psi though.

A Kilby, or other AC compressor powered system can also produce similar output, but require you to use a drive belt off your engine to drive it, etc.

For a typical OBA, the compressor alone will not keep up with air tools, you need a tank, and a regulator.

The flow rate of the compressor needs to be able to keep the tank charged long enough to cycle the air tool.

For an impact gun, say to do your lug nuts, you are spinning off a nut, and there's a lag before you do another one...which is a little time to charge the tank between nuts, etc.

For perspective.... 6 cubic feet of air is about 45 gallons.

For a flow of 6 CFM, that means in one minute, you'd use ~ 45 gallons of air....at 90 psi.

:D

So, what's in the 3 gal tank you wanted?

3 gallons of 150 PSI air - That's a charge of air that can allow about 12 gallons of air at 90 psi.

To last ONE MINUTE, you'd need 45 gallons of air....you have ~ 12 gal

That means you have about 16 seconds worth of 90 psi, 6 CFM flow, in your 3 gal tank.

How long to recharge it back to 150 psi?

That depends on the compressor's flow rate, and the duty cycle.

Typically, a few minutes to recharge the tank from 90 to 150 psi....to have another 16 seconds of bursts, etc.

The duty cycle of the compressor limits how long it can run, without needing a cooling off period.

If you have a 100% duty cycle compressor, you can run it for a decent amount of time, an hour or so without a break.

If you have a 30% duty cycle compressor, it may only be able to reliably run for 10 minutes, and then need to cool off for another 30 minutes, etc.

IE: A low duty cycle compressor will not stand a ghost of a chance to keep a tank charged while running air tools.


There are other things to consider for an OBA system...but the above is a good starting point at least.

:wink-big:

Man that was awesome. LOL

whoa... thanks for the info.... I know some people with mini trucks on air bags and I can get a deal on a small Viar compressor and a 3 gallons tank... but the viar is only a 30% duty cycle so thats not going to cut it....hmmm..... back to the drawing board! thanks again!!! What compressor do you have tj? also what do you typically use your OBA for?

I have an ExtremeAir 100% Duty Cycle 4 CFM, 150 psi compressor. The 4 CFM is at ZERO PSI though.

Its mounted under the hood.

I have a 4 gal 150 psi tank mounted under the driver's seat, where the OEM muffler used to be.

I have some Mil Spec solenoids for the tank which turn the compressor off when the tank is full, and on when the pressure drops....plus a manual overide switch on the dash to keep it from running when not needed (Like when I'm asleep...)


I use it MOSTLY for airing back up after wheeling...and I can reset blown beads, and run air tools in a limited fashion, like spinning off lug nuts, air-hammer, etc.

I'll see if I can move some pics...

Great summary TJ.

I'm running a Viair 400c mounted underneath near the rear axle. It's connected to a 2.5 gal tank that is in the spot that used to hold my spare tire. I've also got a solenoid valve that cycles the compressor on at 110 psi and off at 145 (IIRC). That is connected to a dash switch via relay so I can completely turn it off when not needed. I typically air down my 33" tires to 20psi or so. I get my first tire inflated to about 30 psi before the comressor kicks back on to recharge the tank. From there on out the compressor is running constantly while I air back up. I really should have gone for a larger tank. I haven't tried running tools off of it, but expect I'd have similar experiences at TJ.

whoa... thanks for the info.... I know some people with mini trucks on air bags and I can get a deal on a small Viar compressor and a 3 gallons tank... but the viar is only a 30% duty cycle so thats not going to cut it....hmmm..... back to the drawing board! thanks again!!! What compressor do you have tj? also what do you typically use your OBA for?

The Viair 480C is a 200psi Compressor , 100% Duty Cycle @ 100psi or 50% Duty Cycle @ 200psi

We typically run a dual pack of these in most of our minitrucks and full sizes for OBA for our airbags.