Air tank size

[fifty]

I am going to get an air tank for my truck and debating sizes. I am going to run Arb's front and rear, air lines for 37 inch tire filling and potential air tools front and rear.
The truck is a f350 cclb so I have tons of space.

Do I go 9 gal? 12 gal? As big as I can stuff in the spot I am going to fit it in?

Any reason bigger is not better on this one?

 

[TheAlmightySam]

What compressor will you be running? That will tell us a lot. Some of the smaller compressors don't have the duty cycle to fill a massive tank. On the other end of the spectrum, if you're running something like a York that makes an unbelievable amount of air, there's almost no reason at all to run a tank, or at least not a very big one.

 

[fifty]

I think it's going to end up being one of the extreme air magnums.

 

[fifty]

I would love to go engine driven, but that alone doubles the cost. Well, maybe...close...

 

[TheAlmightySam]

With a compressor like that, which puts out a "medium" amount of air, tank size will depend on what air tools you intend to run, and for how long.

For example, your projected tires are somewhere around 5.75 - 6 cubic feet, meaning that compressor should be able to fill them from zero to drive pressure in something like two minutes. That's pretty fast, and were you just doing that with the compressor, I wouldn't even bother with the complication of a tank.

An air impact, for example, uses a lot of air, but only in very short bursts. In this case, to just remove a tire, I can't imagine you needing more than a couple three gallons of air - probably less. Throw a 5 gallon on and call it good. Obviously more capacity doesn't hurt anything, but it's more expensive, difficult to package, and if you never use that capacity, it's a waste.

 

[bjohnston115]

i run a york 209 and a 3 gallon tank. At idle (750 rpm) the tank pressure will drop to 70ish (from 120) when filling my tires. When i lock the hand throttle at 1200 rpm the tank never goes below 100 psi.

 

[fifty]

Ordered a magnum and their 4.5 gal tank...Figured its best this way. Plus 100% duty cycle...so no slowing down...and its more or less idiot driving proof. Less worry about mud and water...

 

[mog]

on-line calculators or formulas ?

Are there any on-line calculators or formulas to calculate what size air tank(s) are needed to raise tire pressures. I’m trying to be able to re-inflate as quickly as possible and tax my compressor as little as possible by using air tank(s) as reservoir(s). I have plenty of space so that is not a limiting factor.
-
Vehicle - Mitsubishi Fuso FG
Compressor - ARB CKMA12 (3.0 CFM @ zero psi, 2.3 CFM @ 29 psi) 50% duty cycle
Air Tanks on hand -3 two gallon, 1 four gallon
Tires - 37x13.5-16 (7.43 cu ft of 'air space') {(7.46*1.12)-(1.40*.75)}
Normal 'street' pressure - 55 psi
Air-down pressure - 20 psi
-
So if I want to raise my air-downed pressure from 20 psi back to my street pressure of 55 psi, I will want to increase the pressure of 7.43 cu ft by 35 psi. I’d say 150 psi stored in the tank(s). I’m sure there is lose as pressure increases/decreases during the transfer, so not a direct numbers game or it would be easy. Also the compressor’s CFM will decrease down to around 1.5 CFM (??) at 55 psi.
-
So is there a good way to figure out how much (in cubic feet) of 150 psi ‘air’ I need to store per tire (then of course times 4) ?

 

[Wh1t3nukle]

I can share that the compressor you stated there will not last for 37s. Also, unsure of the source used for the spec numbers, but there is link for all ARB compressor specs: http://store.arbusa.com/Assets/PDF/compressorTechnicalSpecifications.pdf

I used the that CKMA12 with a 5g tank for almost 2 years for 35s. Airing up at higher elevation takes longer = longer running time = impacts the duty cycle. I burned it up this past summer, yet did get it warrantied.

The factory pressure switch is like 90 on 110 off. Putting a higher cutoff switch increases running time.

Your goal is to reinflate "as quickly as possible". That is near impossible to gauge being purely subjective....

It took me (using said ARB) roughly 30 minutes to air up 35s from 12-15 psi up to 25-30 psi (driveable pressure) at elevation (~+6000 feet). The elevation part is important to keep in mind (Bernoulli's principle). This took into account duty cycle time as a precaution.

Compared to your tire size and desired air up....yikes!

The tank size is not appreciable enough for all tires. It's only helpful for that first tire. CFM is the factor driving this.

This is also a good thread to look at if you missed it: http://www.expeditionportal.com/forum/threads/117036-OBA

Hope that helps

Are there any on-line calculators or formulas to calculate what size air tank(s) are needed to raise tire pressures. I'm trying to be able to re-inflate as quickly as possible and tax my compressor as little as possible by using air tank(s) as reservoir(s). I have plenty of space so that is not a limiting factor.
-
Vehicle - Mitsubishi Fuso FG
Compressor - ARB CKMA12 (3.0 CFM @ zero psi, 2.3 CFM @ 29 psi) 50% duty cycle
Air Tanks on hand -3 two gallon, 1 four gallon
Tires - 37x13.5-16 (7.43 cu ft of 'air space') {(7.46*1.12)-(1.40*.75)}
Normal 'street' pressure - 55 psi
Air-down pressure - 20 psi
-
So if I want to raise my air-downed pressure from 20 psi back to my street pressure of 55 psi, I will want to increase the pressure of 7.43 cu ft by 35 psi. I'd say 150 psi stored in the tank(s). I'm sure there is lose as pressure increases/decreases during the transfer, so not a direct numbers game or it would be easy. Also the compressor's CFM will decrease down to around 1.5 CFM (??) at 55 psi.
-
So is there a good way to figure out how much (in cubic feet) of 150 psi ‘air' I need to store per tire (then of course times 4) ?

 

[mog]

I can share that the compressor you stated there will not last for 37s. Also, unsure of the source used for the spec numbers, but there is link for all ARB compressor specs: http://store.arbusa.com/Assets/PDF/compressorTechnicalSpecifications.pdf
I used the that CKMA12 with a 5g tank for almost 2 years for 35s. Airing up at higher elevation takes longer = longer running time = impacts the duty cycle. I burned it up this past summer, yet did get it warrantied.
The factory pressure switch is like 90 on 110 off. Putting a higher cutoff switch increases running time.
Your goal is to reinflate "as quickly as possible". That is near impossible to gauge being purely subjective....
It took me (using said ARB) roughly 30 minutes to air up 35s from 12-15 psi up to 25-30 psi (driveable pressure) at elevation (~+6000 feet). The elevation part is important to keep in mind (Bernoulli's principle). This took into account duty cycle time as a precaution.
Compared to your tire size and desired air up....yikes!
The tank size is not appreciable enough for all tires. It's only helpful for that first tire. CFM is the factor driving this.
This is also a good thread to look at if you missed it: http://www.expeditionportal.com/forum/threads/117036-OBA
Hope that helps

Thanks ! !
That is the info I was looking for (although not what I wanted to hear :sombrero: )
Your real world experience beats any formulas or calculations.
It sounds ike I need to get a 'real' compressor and use the space I had set aside for tanks (I'll still use one) for other equipment.
So maybe:
ExtremeAire Magnum ($565)
•100% Duty Cycle
•150 psi
•6 CFM @ 0 psi
•2.6 CFM @ 100 psi
•95 amp draw
OR
Puma ($227 w/tank)
•100% Duty Cycle
•125 PSI
•3.4 CFM @ 40 psi
•3 CFM @ 90 psi
•30 amp draw

 

[Wh1t3nukle]

Glad that could be helpful. Maximizing space in an efficient manner seems to be paramount in this type of hobby.

Without knowing what your goals are for this system, above tire filling and the rig setup/type of usage, I'd recommend max tank size at 5g. I'd be sure that you account for that current draw of those 2 systems. Meaning your battery and alternator specs meet the need + other mods used simultaneously.

For those 2 systems you noted, based on the thread I linked to you'd find good feedback about the Puma.

Share what path you go, but I (and others) still recommend a EDC instead.

Case in point -- I filled 8 tires last night from 10-12 psi up to high 30s in less than 15 minutes.

 

[mog]

Glad that could be helpful. Maximizing space in an efficient manner seems to be paramount in this type of hobby.
Without knowing what your goals are for this system, above tire filling and the rig setup/type of usage, I'd recommend max tank size at 5g. I'd be sure that you account for that current draw of those 2 systems. Meaning your battery and alternator specs meet the need + other mods used simultaneously.
For those 2 systems you noted, based on the thread I linked to you'd find good feedback about the Puma.
Share what path you go, but I (and others) still recommend a EDC instead.
Case in point -- I filled 8 tires last night from 10-12 psi up to high 30s in less than 15 minutes.

There is no easy way to mount an EDC under the hood (well, under the cab in my case).
I think I will go with the Puma do to it's reviews here and on IH8MUD. Also the price point seems very reasonable for its performance.
Thanks again for the enlightenment.

 

[Firesong]

Has anyone ever simply carried a scuba tank with regulator? 3000 psi goes a long ways towards filling tires.

Example. Scuba tank to old paintball air tank rated at same pressure. (I mention the small tank the size of a football which makes it easy to carry tire to tire. ) Output regulator on small tank can be set to any output you want. Blow up those huge 38" tires in no time.

 

[verdesardog]

I have a viair 200psi compressor and 2.5 gal tank. the compressor is rated at 100% @ 100psi. When inflating, the tank pressure drops fast but then when below 100psi the duty cycle keeps the compressor safe for extended run time. It inflates 4 tires in less than 15 min. Plus with a regulator inline set to 120psi feeds my pac brake and air horn.

 

[mog]

Has anyone ever simply carried a scuba tank with regulator? 3000 psi goes a long ways towards filling tires.
Example. Scuba tank to old paintball air tank rated at same pressure. (I mention the small tank the size of a football which makes it easy to carry tire to tire. ) Output regulator on small tank can be set to any output you want. Blow up those huge 38" tires in no time.

In the past I've used a 'B' size bottle of nitrogen (1800psi) simple because I can fill it anytime from our 3000 cu-in bottles at work (corporate aviation), so free and always available.
I used a fixed pressure helium balloon regulator that I modified to fit the nitrogen bottle's head. I did this since that way it was very small and nothing like gauge(s) or an adjustable regulator to get banged up.
I had it set to a fixed 30 psi when I was driving my FJ40. It worked great. Of course a little bigger then the commercial set-ups that use CO2 and heavier then a SCUBA tank since it was steel, but the 'free' refills out weighted those. And of course with a fixed regulator it would not run air tools, but that was not a requirement for me.
I'm looking for a compressor so I am not tied to refilling the bottle on long trips (aka: away from free source).