This may be old news to a lot of you. Bottles 5 to 10 years old have a valve that will not close after the appliance is disconnected. I used an older bottle and when the torch was unscrewed I could hear a hiss. I checked my stock and found a total of 5 that leaked. Yes, I had a lot. Earthquake kit. I live in San Francisco. There was a recall approx. in '12. Worthington no longer stands behind them. They made them for many lables. Get them outside away from any ignition source. CP