47kg cas cylinder volume.....

[Maker]

I've just googled it and one place said 91.8 litres. I also found that 1 kg of propane = 1.985 litres and the tanks are filled to 90% (for expansion): 47kg x 1.985 / 90% fill x 100% = 103 litres. I think the only way to be absolutely sure would be to weigh the tank empty, fill it with water and weigh it again: full water weight(kg) - empty tank weight (kg) = volume in litres.

 

[normspanners]

AGH!!!, LOOK ON THE CYL if it says ***WC thats it !!!! water capacity
and no it will not make it easier on your compressor it will pump till it cuts out/ high pressure, if it is a 10cfm then that is it 10cfm it will just run for longer filling the extra space, the air will last in the tanks longer till the pressure drops to your cut in pressure then the compressor has more work to fill them.
Lowering your differential pressure ie raising the point at which the compressor cuts back in will keep a more constant air flow.
Basically what is used, has to put back in, and the longer the compressor is off the longer it has to run to keep up. You can get away with a small compressor only for so long, until it runs out of air then you have to play the waiting game.
Whereas if your compressor can just keep up with the usage it is better to keep it pumping ie lower the diff.

 

[Bill Edwards]

Don't go to much trouble figuring out how much air is held, it's a fair bit. Just ask yourself whether you need the extra capacity or not and don't worry about the exact amount!

If you are running tools for short periods of time where the compressor can't keep up with the demand then adding a tank will allow you to go on for longer, though it will take longer to fill the tank. Depending on your usage this may be OK for you.
If it keeps up with everything you ask of it already then don't add another tank. It's more points for air leaks (which will create more work if you end up wasting air) and the compressor will still have to run for the same amount of time, but it will get hotter as it'll be running for longer, just less often.

Or connect it and turn the cylinder off when you don't need the extra capacity - a favorite method of mine. Best of both worlds are then available.