Thursday, April 28, 2005

A close call

A few months ago, when I was alone at the house during a weekend, I was cooking dinner when suddenly the fire in the gas stove snuffed out. Puzzled, I came closer to investigate thinking that I ran out of LPG in the middle of the night. I noticed a faint hissing sound and the distinctive smell of mercaptan. I realized that the hose connecting the LPG cylinder and the oven has completely come off and it was leaking LPG into the room!!! I immediately shut off the gas cylinder and the oven. Conscious of the fact that I wasn't supposed to turn on or off any electrical appliance in a potentially explosive atmosphere, I refrained from turning on the exhaust fan and just opened the doors and windows of the kitchen to let the LPG dissipate naturally. This cold have been much worse since I sometimes go to my room while I let the food I'm cooking simmer for a long time. Luckily this time I was in the kitchen when it happened. I shudder at the thought of what might have been. The room could have filled with LPG and a tiny spark from somebody ringing the electronic doorbell or the phone ringing could have set it off. Kaboom!

The problem was that the hose connector to the oven was not put on tightly enough and over the years of use it must have slipped off. Opening the gas cylinder pressurizes the hose and the repeated pressurization over the years undoubtedly contributed to that also. Whenever a new cylinder is installed I don't usually bother to the end connected to the oven, I'm just concerned that the end connected to the cylinder and pressure regulator is snuggly fastened.

An interesting fact about LPG is that it's heavier than air. Composition is roughly 50-50 propane and butane which are both gaseous hydrocarbons with larger molecules (thus heavier) than air. So what does this mean? It means that LPG tends to flow and settle at low points of the house. It could be at the floor or if you have a basement it would flow down there too. Opening a high window won't dissipate the accumulated gas fast enough. It is better to open the doors too. I attended this safety seminar once where they demonstrated that LPG indeed flows and does not dissipate in open spaces by pouring LPG down a long half-pipe. They lighted the other end and sure enough I saw the fire climb up the half pipe. It was even done inside a hotel seminar room and there were nervous hotel staff with fire extinguishers on standby. Also have you ever wondered about the awful stench of LPG? It's actually added on purpose. Pure Butane and Propane are both odorless. A substance called Mercaptan is added to stench the LPG so that you know that there's a gas leak. Nice huh?

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