was welding up my chassis today. Using co2 that local pub gave me which works pretty good, but after a few hours in the sun I heard this hissing sound which was coming from the bottle. On inspection the bottle had got quite warm in the sun and the hissing was coming from the what looks like a pressure release valve on the regulator. I moved the bottle into the shade but noticed one of the pressure gauges was right round at max. The other gauge continued to read the pressure I’d set. What’s going on ? Has it just got too hot, is the gas about to run out ?