Putting Out the Fire

September 2012

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Fire trucks have to be built at top-grade level–lives depend on it. Unlike so many vehicles that are all about bells and whistles, the only bell that matters to these drivers is the fire bell. But with mounting equipment and such a long body, engines need to be built with greater thought for safety, while at the same time being able to get to the scene as quickly as possible.

Safety is the focus before the truck ever gets to the scene of a fire.

John Wallace, chassis engineer manager for Ferrara Fire Apparatus, which designs and manufactures fire trucks, says in recent years there have been important changes to the way firefighters ride and to the speeds used to reach a fire. "You used to have two door cabs with open rears–people could get in and out faster–but the firefighters kept falling out so it became designed for four-door," he says. "Another [improvement] was a requirement to put electronic stability control on. It's a braking system where if you're going into a turn too fast it will drop your accelerator down and will eventually go to braking–you won't be going faster than 60 miles per hour. This is put in place to prevent rollovers."

Standards

There also has been a National Fire Protection Association (NFPA) standard added requiring a vehicle data recorder, not seen in most classic trucks, Wallace says. "It's a box that records different engine stops, tells if you had your seatbelt on or not–that's standard in all fire trucks these days." Fireapparatusmagazine.com stated that out of 406 deaths from responding to or returning from calls from 1977 to 2006, more than 76% of the victims were not belted.

Water from a hydrant is cooled to reduce engine coolant temperatures.

Cooling also continues to be a chief concern. "There are auxiliary cooling modules so when pumping, you have circulated pump water," he says. "Hydrant water is going through a cooler to help reduce engine coolant temperatures."

Wallace says many of the adjustments to fire trucks are via U.S. Environmental Protection Agency (EPA) mandate. Urea has been a key part of the injections system, Wallace says, put into the exhaust between the particulate filter and the selective catalyst reduction. Fireapparatusmagazine.com defines urea as "A nitrogen compound that occurs naturally or is synthesized from natural gas and transforms into ammonia when heated. It's used in a variety of applications, often as a 'scrubber' agent to reduce pollution from smoke-stack industries and as a fertilizer in agriculture." With the need to be sensitive to emissions, the turbo design changes to injectors to burn cleaner has helped in durability, Wallace says.

As one might expect, not all changes have been met with universal firefighter acclaim. "The truck can run as long as you need it to. But if you go back to the fire stations and start it back on, it will be in 'limp' mode until you put urea back in," Wallace says. "With some set-ups, you're forced to set the truck stationary and do forced regeneration. The fire departments don't buy trucks every year and it's a big culture shock because now you're dealing with a complete change in what you're doing. But adjustments are going to continue to happen."

Eric Butterman is an independent writer.

The truck can run as long as you need it to. John Wallace, Chassis Engineer Manager, Ferrara Fire Apparatus

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by Eric Butterman, ASME.org