By Carl J. Haddon
When you arrive at the scene of an MVA, is it your department’s SOP to stretch and charge a line? Perhaps a better question would be, do you ever deploy and charge a line at the scene of an accident? Beyond the matter of departmental SOPs, why or why wouldn’t you use this tactic?
This is not by any means a “rural” set of questions or issue. I’ve recently asked fellow firefighters/officers this same set of questions from departments of all shapes, sizes, and locations. The most common answer I’ve received is: “It’s our SOP, we should, but most often we don’t.”
I can certainly see an argument for both sides. Simple intersection T-bone, non injury, “nothing burger,” why stretch? Rurally speaking, a vehicle dodging an elk on a two-lane highway, swerves, overcorrects and rolls the vehicle. If there are no obvious signs of fire and no fuel leakage, why would I want to deploy a line and block the entire highway if I don’t have to? Allow me to add a new wrinkle to your thought process.
Vehicles have changed dramatically. The addition of Class D (combustible) metals and Lithium Ion batteries will (or should) make you rethink whether or not to stretch that line at the site of a crash. If for no other reason, you might want to consider doing it for your crew’s personal safety.
A typical highway vehicle that is five to 10 years old on the road today contains an average of 35 pounds of combustible metal (mostly magnesium). By this time next year, in 2020, the average vehicle sold around the country/world will contain an average of 300 pounds of various combustible metals. By the way, have you had the unforgettable experience of trying to extinguish 300 pounds of burning, white hot metal that explodes when you hit it with water? Granted, the number of vehicles that spontaneously burst into a full blown Class D fire is pretty nonexistent. However, there is a new-ish fuse, or accelerant, for this mass of combustible metals found in today’s new hybrid and electric vehicles. It is known as the Lithium Ion battery.
Lithium Ion batteries catch fire because of a process called “thermal runaway.” Thermal runaway is usually (but not exclusively) caused by one of two things: a malfunction of the charging system or physical damage (i.e. accidents). I won’t bore you with a lot of the science, however it is important to know where these batteries are located and how they burn. My personal/professional experiences with burning Lithium Ion batteries is that they sound like a small jet engine and resemble a small erupting volcano. Lithium Ion batteries have many cells. When they ignite, they spew molten copper and aluminum (great for turnout gear); they look like a blow torch; they off gas hydrogen, which makes for secondary flash fires; and the smoke produced (preignition through overhaul) by burning Lithium Ion batteries is wicked toxic.
Lithium Ion batteries are generally located beneath the floor in the rear seat area, or in older models they are “L” shaped, and basically conform to the shape of the back seat. Many hybrids will have a small gas tank located directly behind the vertical portion of the battery in the trunk area (just to make the firefight easier). European testing on these vehicle-sized Lithium Ion batteries shows that (if you can get to them) it takes an average of 3,000 gallons of water to be able to knock one of these batteries (to reduce the auto ignition temperature). It is not uncommon for it to take 45 minutes to fight one of these car fires with the Lithium Ion battery going off. Additionally, it is also not uncommon to have reignition some 48 hours later because of ongoing thermal runaway.
If trying to get to a burning Lithiu