Question:
CO2 Fire Extinguisher as CO2 source Does anyone know of any issues regarding this? I New Zealand the smallest CO2 cylinder one can get is the 7kg so I'm investigating alternatives from Soda Stream to fire extinguishers...

Answer: -Nominal pressure of any kind CO2 pressure bottles is the same - about 6 MPa. The problem is valve. Fire extenguishers has different kind of valves than welding or brewery bottles.

-You better check on the pressure ratings on those tanks. I don't recall those tanks containing liquid CO2. The rating for 'real' CO2 tanks is up somewhere around 3000psi.