WATCH ABOVE: Scarborough home explosion caught on camera.
TORONTO – The Ontario Fire Marshal said Tuesday gas may have contributed to the explosion which destroyed a home in Toronto, damaged nearly 40 others, and left one person dead.
Gas also played a role in an explosion in March which destroyed a Manhattan building and killed two people and injured nearly two dozen others.
The explosion in Scarborough was caught on the dashboard camera of a neighbour as they pulled out of their driveway. It shows what appears to be insulation and bits of the roof flying off and landing on surrounding homes.
Ontario Fire Marshal Wayne Romaine said during a press conference Tuesday morning the primary investigation is focused on figuring out what kind of gas or fuel caused the explosion.
Investigators have not determined whether the explosion was suspicious.
How it explodes
Gas and propane are highly combustible and can exert intense pressure when ignited. The Ontario Fire Marshal is still trying to figure out what caused the ignition.
But gas can leak from a variety of sources like a gas stove or broken pipe – either way a person inside the home would generally be able to smell it.
The gas seeps out and mixes into the air, filling the room before moving on to the rest of the home.
“Gas tends to mix really well with the surrounding air just because it’s coming out relatively slowly and normal air motion will mix it in and as a result,” David Checkel, a professor at the University of Alberta said in a telephone interview Tuesday.
“It tends to be smellable long before you build up to an explosive concentration and in fact it would smell very strongly by the time you reach an explosive concentration.”
A spark near a gas leak can cause an explosion when the concentration of gas nears 5 to 15 per cent of the air, according to the American Gas Association.
And a variety of things from a lighter, candle or an electric motor switching on or off can cause the ignition.
“A light or a candle will definitely ignite it,” Checkel said.
And the fact that there wasn’t fire or smoke isn’t particularly unusual, he said.
“What tends to happen, the gas itself, whatever is mixed burns very quickly, the flame runs through it, so there isn’t some pool of leftover gas that is not ignited and produces a fireball after the ignition, so it tends to just all burn as its pre-mixed,” he said.
“The flame flashes through it, the pressure builds up, and the walls blow out, the roof blows off.”
When gas burns it expands roughly six times and “starts pushing everything out,” Checkel said.
“So that pressure projects everything away and you end up with the roof is often pushed out, and the windows and doors tend to go flying toward other buildings.”
Gas explosions aren’t rare and have happened elsewhere including a March explosion in Manhattan, last week in Fresno, California, and in New York in March, 2014.
What is the gas?
It’s still not clear whether it was natural gas, propane, or gas which seeped up into the home from underground.
There wasn’t much fire damage, Romaine said, and very little smoke – but that doesn’t necessarily mean it was a certain type of gas. Instead, Romaine said, it indicates the fuel was “spent” after the initial explosion.
WATCH: Ontario’s Fire Marshal explains how the explosion may have produced very little smoke or fire.
“The fuel has delivered as much energy as it possibly can, it’s given as much bang for the buck, as it were, so that’s why you have this massive debris field as we have it, and with very little fire damage to the debris,” Romaine said. “So that is an indication to us that the fuel was spent, once the explosion took place, the fuel itself was spent.”
Natural gas is widely used in Canada, with nearly 47 per cent of Canadian households using natural gas as their main heating fuel, according to Statistics Canada.
What to look for
Natural gas is primarily used inside homes for heating and cooking but is also highly flammable.
Romaine said part of the investigation is going to focus on whether neighbours smelled anything prior to the explosion.
Natural gas is odourless. As such, gas companies add mercaptan to the gas to give it a distinct smell – sometimes described as rotten eggs – so people can figure out quickly whether there is a leak.
“What we’re hoping is, whether or not individuals smelled the mercaptan,” Romaine said. “Was there any type of odour that was picked up?”
WATCH: Ontario’s Fire Marshal confirms the search for bodies continues.
What to do if you smell gas
Enbridge Gas, which supplies gas to homes in Ontario, suggests people should steer clear of phones, cameras, and other electronics, and leave light switches, appliances, and computers as they are inside a home.
People should also open doors and windows to let fresh air in and listen for a hissing sound before going outside.
If you think the leak is outside, Enbridge Gas recommends putting out all open flames and leaving the area before calling emergency crews.
– With files from The Associated Press
Comments