Advice please, I have bought a second hand Mig welder which came with a 35kg nearly full bottle of gas, the bottle is Grey in colour with a Mauve top / shoulder
Air Liquide on the side. it has a regulator attached, with a grey knob to the right
When I open the valve the needle shoots round to the stop.

1) should I be using this type of gas with the type / identity not known?
2) if yes how do I regulate the output?
3) where on the gauge would be a safe operating setting?
4)Don,t use its not safe etc!
I will ask the chap I bought it off tomorrow which gas it is but I haven't got his mail at the moment.
Air Liquide on the side. it has a regulator attached, with a grey knob to the right
When I open the valve the needle shoots round to the stop.

1) should I be using this type of gas with the type / identity not known?
2) if yes how do I regulate the output?
3) where on the gauge would be a safe operating setting?
4)Don,t use its not safe etc!
I will ask the chap I bought it off tomorrow which gas it is but I haven't got his mail at the moment.