Steam is a natural byproduct of applying water on fire for suppression, and it can be a good thing. However, many in the American fire service fear it. Lars Agerstrand, battalion chief with Varnamo Fire & Rescue, came all the way from Sweden to talk about why he doesn’t think it’s as bad as some in the states think.
In his class at Firehouse World titled “Steam: What Do We Know & How Does it Affect Firefighting,” Agerstrand said steam becomes thermal ballast in smoke and hot gases and helps in cooling to affect suppression.
“We want more stuff in smoke and we want it to be cooler,” Agerstrand said. He said steam helps suppression and suppression is different than extinguishment.
“You still have to go in with water and put the fire out,” he said.
Agerstrand used scientific and medical studies to help dispel the thought that steam will cause harm to potential victims and firefighters. Because fires have to be very hot to produce steam, victims will have suffered injuries far worse than anything steam could produce, Agerstrand said.
“The space would become untenable,” Agerstrand said. “You would be dead long before you would have any issues with steam. It’s a non-issue.”
Agerstrand said studies dating back to the 1940s and 1950s have looked at steam and its effects on fire and life. There’s a new study underway being done by Underwriters’ Laboratories and Agerstrand is hopeful it will confirm what he believes to be true.
“There would be all kinds of issues already happening worse than steam,” he said. “The improvements made by the application of water would be better than without. It’s a question of survivability.”
From a firefighting perspective, Agerstrand said steam cools and that’s the most important part of having a fire go out. He explained that open flame is not supported at temperatures below 2,330 degrees F, and water is the agent that makes cooling happen. Water applied to hot surfaces, hot gases and flames, Agerstrand said, stating the basics of firefighting.
“Surface cooling problems are rarely flow, its access,” he said. “If you can’t cover the fuel surfaces, you can’t put the fire out.”
To back that argument up, he said fire can be extinguished with as little as one gallon of water per minute per square meter.
“The amount of water you need is ridiculously small,” he said. “That has been confirmed over and over in research.”
Agerstrand said ultra-high pressure water, emitted at 5,000 psi, which makes very small water particles is the preferred method in Europe, but he said any delivery of water will create steam, provided the fire is hot enough.
“If steam is deadly, how come there are steam saunas,” he said. “It can’t be the point of vicious attack as the spawn of the devil. Even if you don’t like steam, you are going to have to use it.”
