Thread: Air Tank

Its up to you - the smaller tank would mean that you have less reserve, but filling that reserve will take less time. You need to think about why you actually want the reserve anyway, and go from there.
When pumping up a tyre, the larger the reserve, the less the overall time taken to pump up the tyre, but the longer the time to repressure the reserve tank. The overall time running the compressor will be the same, regardless of the size of the tank, provided that the tank is brought back up to pressure. In other words, the compressor time that is saved by having the air in the tank available is needed to refill the tank. Consider the compressed air as stored energy, and it is simply an application of the law of conservation of energy.
This assumes that the compressor is equally efficient at all pressures, which it probably isn't, although the difference is, I expect, not that great in practice.

John

Should be easily solved with a few isolating valves:

Usually the compressor fills the 9L tank. When you use the tank to inflate a tyre and it's used-up, close the valve from the tank and let the compressor go straight to the tyre. When the tyre is fully inflated, disconnect the tyre and open the valve from the compressor to the tank again, until it's full.

My setup is a 12 liter tank. One of my lines has a leak. Means I get the pressure up to 50psi before it starts leaking.

how many 235/70/16 tyres will a 9litre tank inflate?
from say 20 psi up to 35?

Originally Posted by Leo109

Should be easily solved with a few isolating valves:

Usually the compressor fills the 9L tank. When you use the tank to inflate a tyre and it's used-up, close the valve from the tank and let the compressor go straight to the tyre. When the tyre is fully inflated, disconnect the tyre and open the valve from the compressor to the tank again, until it's full.

I agree. If anything, go to a larger tank with an isolating valve.

The main advantage I see with a larger reserve cylinder is for reseating a tyre on to rim after puncture repair.
Sometimes the disadvantages of actually carrying the cylinder (ie finding room for it in with all the other stuff) outweight the advantages. As has been said, the compressor is going to have to run for the same amount of time anyway.

Originally Posted by Pedro_The_Swift

how many 235/70/16 tyres will a 9litre tank inflate?
from say 20 psi up to 35?

It depends on the pressure in the 9L tank!
It takes 27.72L to inflate a 235/70/16 from 20psi to 35psi.
Assuming constant temperature, a 9L tank will deliver enough air if it starts at 150psi. It will drop to 35psi and deliver 27.72L! (calculations can be provided if you really care)

I could probably work out a general equation for calculating volumes of air tanks based on required volumes and pressures etc. Could be handy!

go the best of both worlds and use a 3way tap between the compressor and the tank (make sure the regulator switch is bewteen the valve and the compressor)

in one position (neutral pos) it will feed the tank from the compressor
in one position it will feed a jack from the compressor without the tank
and in the last position it will feed the jack from the tank (usefull for if you are at a servo and want to fill the tank NOW. or if you have other accessories that run off the compressor like a difflock.