How long does an air tank last ?

[voipio]

A small 12V fridge type compressor will probably take the best part of an hour to get a 47kg gas bottle receiver up to pressure.

 

[sardine]

You must have a power supply to run the plasma cutter so why not just run a normal compressor from that?

If you want an accurate number then you need to find out:
Working pressure of the fridge compressor,
Water capacity of the gas tank
Consumption and operating pressure of the plasma cutter.

The gas tank capacity will be stamped into it somewhere, the other info should be in the manual for the plasma but you might have to find a service manual or something for the fridge.

I run my workshop off a generator so the plasma will be maxing the generator out on full power, I can't run a compressor at the same time.

 

[AKN]

Why not use an engine driven compressor, will probably give more air per gallon of fuel than putting a generator and motor between the two.

 

[Richiew]

I've recently upgraded from a 24 litre to a 150 litre compressor. I would say buy the biggest one you can reasonably afford. I'm sure the 150 litre jobbie will do everything I need it to do, but it still empties much quicker than I anticipated.

I couldn't source a single phase 200 litre vertical compressor unfortunately, so I had to compromise.