I started building my HHO system a couple of weeks ago and finally finished it. While testing it, I didnt see the volume of gas as other systems so I increased the NOH. It began bubbling at a good rate, but was still unsure if this was hydrogen or just steam. I rigged a torch tip to the hose and was going to see how flammable this gas was. It did not light. I think my bubbler had too much air volume and it was still purging air and not hydrogen. I disconnected the bubbler and placed the tube from the top of the HHO canister into a 16oz plastic bottle. I was going to make a cool bottle rocket. With the plastic bottle upside down and the gas being blown directly into the bottle (without that useless bubbler), I put a lighter to the bottle. My plan was to crimp the supply line with needle nose pliers to prevent any back fire into the canister, before I actually touched the bottle with the flame. The gas must have leaked and accumulated around the base of the bottle. My flame never even came close to the bottle when everything ignited at once. The bottle blew up in my face and backfired back into the canister, blowing the top off. The top hit my daughter's boyfriend in the face and required stitches. Its been a couple of hours and my ears are still ringing. This system is definitely not a toy. I will not disrespect it again.