Air tank

[Nuckingfuts]

from experience how many litres makes a good size air tank? I am going to make one but unsure of a suitable size. Whats too big or too small? will be running air lockers, big tyres etc

[jessie928]

from experience how many litres makes a good size air tank? I am going to make one but unsure of a suitable size. Whats too big or too small? will be running air lockers, big tyres etc

hi mate

it depends on the flow of your air pump. you have to size the tank accordingly

JEs

[Nuckingfuts]

ah fair enough. I have the new ARB compressor (the big one, not the locker one) not sure what the flow rate is off the top of my head though. thanks for your help

[superzuki]

how do you work out what size tank is needed for what flow rate?

[zagan]

At first I though this was about a air tank you know one that is floating or like a hover craft. lol.

[Nuckingfuts]

the ARB compressor's flow rate is about 62lpm under load. How do you work it out? compressor cuts out at about 100psi so does the size of the tank really matter?

[hudson44]

the ARB compressor's flow rate is about 62lpm under load. How do you work it out? compressor cuts out at about 100psi so does the size of the tank really matter?

No it doesn't matter. As long as its not massive. I just rigged an OX comp with a 2lt air tank in mine. I ran the ARB pressure switch which cuts out @ 100psi and in at 70psi. It takes about 20 to 30 secs to cut out from empty with a flow rate of about 45 lt/min.

It inflates tyres well and pumps up between tyres which gives the tyre a good initial "burst" of air which speeds up the inflation process.

[jessie928]

the ARB compressor's flow rate is about 62lpm under load. How do you work it out? compressor cuts out at about 100psi so does the size of the tank really matter?

No it doesn't matter. As long as its not massive. I just rigged an OX comp with a 2lt air tank in mine. I ran the ARB pressure switch which cuts out @ 100psi and in at 70psi. It takes about 20 to 30 secs to cut out from empty with a flow rate of about 45 lt/min.

It inflates tyres well and pumps up between tyres which gives the tyre a good initial "burst" of air which speeds up the inflation process.

it actually does matter, but i dont now what the math is.

imagine running 100 litre air tank with teh arb compressor, if it didnt matter, then 100 litre tank would be OK yes/no?

i am guessing 1 minute fill time would be ok. ( from empty)

[Dirty]

The air tank will only give you an initial storage that can flow faster than the straight compressor.

Unless you have 10L or more of air tank the compressor will have to kick in to help out when inflating larger tires. When the compressor is going inflation is slower.

You can also run higher pressure in the tank to reduce the need to depend on the pump, and if you run lockers add an inline regulator to bring the pressure back down under 100psi.

I also noticed a couple of weeks ago when looking at various tanks on the market that NONE of the ones that I saw being sold in the 4WD shops had any Aust. Std. markings, or any pressure testing markings. Not sure about the legalities of this in the real world?

And to that the Piranah 1Lt tank was just a length of RHS with two caps welded on?? For a mere $75!!!

- David.

[Shifta]

I bought a 3Gal (11 Ltr) certified tank from the Air Bagman in perth. It is feed from my Bushranger Max Air compressor. The tank runs my lockers and fills my tyres. A full tank will fill a 33" from 18-38 Psi in under 1 min with the compressor kicking in half way through inflation. Inflation is definately quicker than pumping the tyre direct from the compressor. I also have a water separtor and check valve at the tank inlet. Pumping tyres direct from the compressor will allow condensate to be pumped into the tyre. Using a tank and water separator there is no chance of pumping water into the tyre.

[ISUZUROVER]

the ARB compressor's flow rate is about 62lpm under load. How do you work it out? compressor cuts out at about 100psi so does the size of the tank really matter?

No it doesn't matter. As long as its not massive. I just rigged an OX comp with a 2lt air tank in mine. I ran the ARB pressure switch which cuts out @ 100psi and in at 70psi. It takes about 20 to 30 secs to cut out from empty with a flow rate of about 45 lt/min.

It inflates tyres well and pumps up between tyres which gives the tyre a good initial "burst" of air which speeds up the inflation process.

it actually does matter, but i dont now what the math is.

imagine running 100 litre air tank with teh arb compressor, if it didnt matter, then 100 litre tank would be OK yes/no?

i am guessing 1 minute fill time would be ok. ( from empty)

The size of the tank is LARGELY irrelevant. I am sure there isn't anyone here who is going to fit a 100L tank to a 4x4???

But - if you wanted to run something that needs lots of air, from a small compressor, then 100L would be good.

[micks troll]

I personally run one of those twin piston 150lt/min pumps (autobarn job, after some scum bag flogged my bushranger one) and from memory my tank is around 10ltrs (small truck/trailer tank). It takes around 1min 48secs to fillup to about 97psi and cut's back in around 80 psi, and it takes 22 sec to get from 80 back up to 97ish I've reseated the bead of a 35 with the tank, but the compressor wont last pumping up 4 33 from 12 to 32 as it has a thermal cut out, I've even run a small fan to direct cool air through the compressor and still wont do 4 tyres . I also have the large arb which is soley used for air locker but I'll connect to the tank when I get around to it, then when the other compressor cuts out I've still got a back up!!
Personally I wouldn't go a larger tank as this is reasonable enough, and better once both compressors are running the advantage of a larger tank is you'll have a higher pressure for longer....just
Hope this gives you some idea????
Cheers Mick

[Hobzee]

We do the BOSS tanks. To my knowledge they are among the few that are Aus Std approved. They are alloy and wont rust and are light weight.

They are in 2ltr, 3 litre, 9 ltr and 15 ltr sizes and they are available in the better 4wd shops - I know because we supply them.

You can also call us for a price delivered.

15 litres at 135 psi will inflate a small tyre (say 31") from 20 to 30 psi without a compressor even attached. The smaller the compressor is - the longer it will take to fill. The smaller the tank is the more the compressor has to do. You can't beat a big tank with a big compressor and high pressure.

By the way the BIG ARB compressor is not that big and among the slowest on the market. Reliable = yes. Almost fool proof to instal = Yes. Fast = no.

Big compressors pull big current (similar to winch motors) and warrant big cables.

We have about 15 compressors in our store, including ARB - all rated at speed and current draw.

[80diesel4play]

I have one of Hobzees BOSS compressors running into a 15L tank under the ass of the 80 - takes a bit to do a from empty run to 120Psi buti haved a feeder valve to feed from th local servo to prime the tank!

Will reseat a 35 and bring back to 15psi on the tank lone so pretty good setup all in all.

Takes @10 mins to take 4 x 35's from 10psi to 35psi whihc is pretty reasonable. Running 1/4" lines throughout and 3/8 Line off the compressor with 2 one way valves installed.

Most important consideration is space, what you really need it for and spend teh extra on a good compressor - I went thouga few before I got onto teh good one! Money well spent!

[dansedgli]

Ive got a big boss compressor and 15 litre tank too.

It took bloody ages (4 or so minutes) to pump up from 0 to the 150psi cutoff but takes less than half the time to reach 100psi which is what the airlockers like.

It recharges in about 30 seconds using the 100psi cutoff switch which Im happy with. Its a conversation killer when it switches on though, too loud.

Its great, I can use the rattle gun to undo and do up wheel nuts, I have to tighten properly by hand but it still saves heaps of time.

I thought lockers needed a small tank to operate. If you are using a small compressor I would use a small tank so the compressor isnt constantly running trying to refill it.

[davew]

I bought one of the "new" high output ARB compressors. The air tank on the compressor is much smaller than the older model it replaced.

I added an 11 litre air tank in the end as it was the biggest I could fit under the floor. It seems to give about the right length of time to fill up the tank, not so short a time that the initial start current is wasted and not so long that the motor gets hot.

If it's of any help, here's some calcs I posted on another forum when trying to decide if it was worth doing...

Here are some calculations based on Boyles law and assuming an atmospheric pressure of 14 psi and based on a Simex containing 3.5 cubic feet of air (very roughly 35x10.5 16 tyre)....
To take a Simex from 0 to 10 psi (which is actually from 14 to 24psi thanks to atmospheric pressure) will take 6 cubic feet of air.
To take a Simex from 0 to 25 psi (14 to 39) will take 9.75 cubic feet of air so we need 3.75 cu ft to inflate a tyre from 10psi to 25psi which will take a 2 cfm compressor such as the ARB just short of 2 minutes.
A 2.5 gallon tank is 0.4 cubic feet and will hold 3.25 cu ft of air at 100 psi and 1.11 cu ft at 25 psi giving us 2.14 cu ft usable air above 25psi.

So... when inflating from 10 to 25 psi we need 3.75 cu ft of air and the tank has just over half of that available at the start, the compressor on it's own will take just short of 2 minutes to air up the tyre, with the tank the first tyre will take under a minute to inflate, subsequent tyres will gain up to a minute, depending on how long it takes to move from tyre to tyre as the tank recharges. You also gain back some time each time you stop inflating to check the current pressure. It will take over a minute for the compressor to get the tank back to full charge from 25 psi but I'd have thought at least 30 seconds of that would be accounted for by the time it takes to check the pressure during inflation, screw/unscrew valve caps, move the airline about and, in my case, fit the valve stem adaptor..

I'd guestimate you're looking at 7 minutes with a tank and 10 minutes without a tank to air up all 4 tyres, to save time kneeling in the mud, let the tank finish filling up before each tyre that way, with the tank, you spend 4 minutes kneeling in the mud instead of 8 without the tank

[lump_a_charcoal]

A tank would be more beneficial if using air powered tools as well...

[Nuckingfuts]

taking all this into account, ill think ill work to the 10-15 litre mark and it should be good enough for what i want. Thanks for the help

[vraamm]

i believe bigger tank is faster, as long as you remember to fill it up before you start pumping tyres.

I think of it this way: if you start with a 30L tank at 150psi plus 4 tyres at 10psi and finish with tank and tyres all at 40psi, with compressor running continuously you save pumping at least 30L of 90psi air (equals 180L at 25psi).
If your tank was half the size you would save half as much.

Is this logic flawed?

[BEU77y]

I've got a Twin Tongue compressor and a 6L tank. The tank is a converted fire ext (5kg), it's just a shade narrower than the chassis rail of our Cruiser. Plenty of space down the sides of the rails.

The tank is big enough to give a good initial punch of air, but doesn't take ages to fill up between tyres. It's all switched at 100psi to 85 psi. Lockers are on there way and I already have the nasty truck horns

With noise.... rubber mount the compressor. I've had a few setups and I now use poly piping to/from the compressor and rubber foot mounts for the tank. With the engine idling it's hard to tell if the compressor is running.

I spent good (and big) $$$ the first time and my compressor is still going well.