While fires are rare for new and properly maintained equipment, it is still vital to understand the steps of fire prevention. In a recent article in Equipment World, Tom Jackson explains that fires typically happen when a machine is neglected. Toward this end, trained technicians play a key role in preventing the occurrence.
Jackson spoke with engineers for their opinions on the most common sources of fire and how equipment owners can prevent them.
As Jackson explains, "There are two basic contributing factors to any fire, a source of ignition and a source of fuel. Ignition can be a spark or a flame or just high heat, but in today's complex heavy equipment there can be multiple sources."
Daniel Olson, a licensed professional engineer and certified fire investigator for Warren Forensics, explains how turbochargers provide a constant source of heat. "On an excavator the main hydraulic valve sits right behind the turret in a bank behind the engine," Olson says. "Most manufacturers put a good firewall there, but if you get a 3,000-psi mist of hydraulic fluid you are going to get a combustible mix of hydraulic fluid and air." He adds: "Depending on the fuel-air mixture you can get something pretty bad happening; not explosive, but it will track back to the source of the leak very quickly." The most important step you can take is to keep the engine clean.
Suzanne Smyth, a PhD and physical engineer who works for Exponent, says that overheated exhaust manifolds on heavy equipment, as well as seized bearings or locked brakes can create enough heat to ignite various sources of fuel.
Frayed or incorrectly installed wiring can also wreak havoc on a machine by chafing against other components, eventually setting off a spark when coming in contact with metal.
While the rubber in most tires itself is not a source of ignition, many tire vendors report that poor tire maintenance and switching, in particular leaving shards of metal inside the tire, can present a fire risk.
According to Smyth, batteries pose more of an issue when you are storing or charging them. She emphasizes that, during these times, you should read and closely follow the codes and directions.
You need to be especially careful with "grinding, welding, brazing, soldering," along with "any work or tool that generates sparks or heat." Jackson says all of these "should be kept well away from any source of fuel." He adds: "Be especially vigilant when welding or grinding on equipment that may have fuel or oil leaks or debris that could catch fire. Clean first, then work," says Jackson.
The fuel has a flash point between 126 degrees and 205 degrees Fahrenheit. The auto-ignition point for diesel is 650 degrees, "meaning at this temperature it spontaneously burst into flames without a source of ignition," explains Jackson. Leaky injectors, fittings, spills and fuel lines are all sources of fire that produce diesel fuel.
Hydraulic fuel has a flash point of 400 degrees Fahrenheit and an auto-ignition point of about 650 degrees Fahrenheit. The main sources responsible for hydraulic leaks are poor maintenance, fittings, spills and worn hydraulic lines.
Land clearing and forestry applications pose the danger of dumping large amounts of flammable material onto heavy equipment. In landfills, you have to be careful, making sure that paper and plastic bags don't either get sucked up or wrapped up in the cooling fan. "It is essential that you keep this debris cleaned out of the machine," says Jackson, adding: "If debris is a constant issue, look for equipment that has reversible cooling fans that clean out trapped debris."
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Understand the main sources of fire and how to prevent them.