Don't mess around/don't be cheap with gas fittings and hoses. Use the Compressed Gas Association (CGA) recommended fittings and hoses. Gases used in the welding application can be flammable (acetylene/propane), accelerants (oxygen) or asphyxiants (shielding gases like argon, CO2 or helium). In MIG/TIG systems the gases are asphyxiants. They are to displace oxygen and nitrogen (air) from the welding area. The nature of asphyxiants is if the concentration of shielding gas is high enough, the gas causes the oxygen to no longer support life. Asphyxiation causes unconsciousness and death without warning.
If a picture is needed, visit a poultry farm when they have a disease kill. They back up a CO2 truck, seal the house and than flood the houses with gas, not a bird left alive. We would rather be over the hill than under the hill. Be safe out there.