October 7, 2011
Combine fires cause serious injuries and millions in property losses each year – this harvest is no exception says Daniel Humburg, professor of Ag & Biosystems Engineering Department at South Dakota State University.
"Extreme conditions in South Dakota this fall created a perfect storm of high temperatures, low humidity, dry crops and high winds producing extreme risk of fires during harvest of soybeans and sunflowers," Humburg says. "One Sully County farmer reported having three fires start on his combines in one day."
Humburg says most farmers are aware of how to prevent a combine fire – keep the machine clean of possible fire-causing materials and eliminate sources of heat that could lead to a fire – however, he encourages producers to also pay special attention to the engine and engine compartment.
"A high percentage of all machinery fires start in that area," he says. "We believe the exhaust manifold and turbocharger are the ignition source for the majority of the fires we are seeing."
Other sources of ignition heat include failing bearings and wrapped plant residue. Humburg says producers can identify hot bearings by purchasing a non-contact infrared laser temperature gun for less than $50.
He adds that new model combines pose a greater risk than old models.
"They have a much larger volume of synthetic materials such as shields, panels and fuel tanks that will burn once a fire is ignited," he says. "This increases the risk of a fire that can consume the machine. A smoldering fire in crop residue can easily spread to a fuel tank, hydraulic line or wiring harness and become catastrophic."
Another step Humburg encourages farmers to take to prevent combine fires is to frequently blow any dry chaff, leaves and other material off the machine with compressed air, and to clear off any wrapped plant materials on bearings, belts and other moving parts. Leaking fuel or oil hoses, fittings or metal lines should be replaced or repaired before continuing harvest.
Sunflowers represent a more severe challenge. In the current weather conditions, producers can experience frequent fire events – even with new equipment that is well maintained.
The South Dakota Oilseeds Council has recognized the severity of this problem, and is funding research at SDSU to understand the differences between sunflowers and other crops which make sunflower residue more prone to ignition.
Engineers in the Ag & Biosystems Engineering Department are performing lab tests to simulate the events on a combine and identify the mechanisms of residue ignition. Practical solutions to the hazard are also being explored.
"As we better understand the problem, we hope to develop one or more systems that could prevent many of these fire events," Humburg says.
Tips to reduce fire risk
Until an engineering solution is developed the things producers can do to reduce the risk of fires in sunflowers include:
Reduce rotor speeds while opening the concaves until a few seeds are left in the head. The less aggressive the machine is to the crop the smaller the volume of fine dust produced.
Reduce the groundspeed to unload the machine. Running at a fraction of capacity is not what producers want to do, but will reduce the temperature of the exhaust system as the engine operates at lower pressures and consumes less fuel.
Keep the header as high as practical to take in as little stalk residue as possible. More MOG (material other than grain) means more dust.
Keep the engine compartment and especially the exhaust system as clean a possible.
Add a "chimney" to the cooling air intake to induct air that is above the cloud of dust that surrounds the machine. These fine aerosol dusts are suspected to be the origin of many of the machine fires.
Humburg reminds producers that despite their best intentions and good maintenance, a fire on a tractor or combine can still occur. Smoldering fires in layers of dust may best be extinguished with water. For larger fires, the best source of protection for a combine is at least one fully charged 10-lb. ABC dry-chemical fire extinguisher.
"Only select extinguishers with Underwriters Laboratory approval and have two extinguishers on the machine in case one malfunctions or loses pressure," Humburg says. "Keep one mounted in the cab, and one where it can be reached from the ground. If a fire does break out on a machine, quickly shut off the engine, grab an extinguisher, get out, and get help."
Older machines with primarily steel construction could often be saved with a fire extinguisher. New model machines with poly tanks, panels and shields, can quickly ignite beyond the capacity of a fire extinguisher.
"If in doubt don't risk your life; step away and call for help," Humburg says.
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