# Air tank cfm potential?

1. Jun 13, 2012

### 281mustang

Say I have a 10 gallon air tank, how would I figure out the CFM potential for the given volume?

Also, what is the volume difference between a 10 gallon tank and 10 lbs. tank?

2. Jun 13, 2012

### jbriggs444

Apparently "ten pound tanks" are sold commercially and have a nominal capacity for ten pounds of compressed gas, usually CO2 at a working pressure of around 1800 psi.

At that pressure at room temperature, CO2 has a density of around 860 kg per cubic meter.

10 pounds is around 4.5 kg. A cubic meter is 1000 liters, so a ten pound tank works out to about 5.2 liters -- somewhere around 1.4 gallons. [If you trust my calculations]

So a 10 gallon tank is going to be roughly a 70 pound tank.

Given the size of a 20 pound propane bottle, those numbers seem to be in the right ball park.

CFM... That's a question of orifice size, regulator design and, to some extent, thermal conductivity. One assumes that you're talking about cubic feet of gas produced at STP. There are physics principles involved, but too many variables to be able to provide a meaningful number from first principles. (Explosive release would give you one boatload of cubic feet in quite a bit less than a minute).