Nothing Fine About ‘Fines’ in Harvest
Monday, September 1, 2008
filed under: Harvest/Storage
Fines are not fine at all when it comes to harvesting sunflower. “Fines” — those multitudes of small fibers or fuzz that rub off sunflower hulls during combining and end up accumulating on machine surfaces — pose a real threat of fires. When seeds are dry and engine compartment surfaces are extremely hot , fines can ignite, smolder and sometimes burst into flames. The result, for more than a few sunflower producers, has been a damaged or even destroyed combine.
Farming in central South Dakota, Chuck Todd knows a thing or two about the risk of combine fires during the sunflower harvest. A hot September afternoon, coupled with seed moistures under 10%, can aggravate the situation in a hurry, he affirms.
That’s a primary reason why Todd Ranches likes to harvest at a little higher moisture content. “If we can get in at about 12%, it really minimizes the threat from all those little fines,” Todd says. “Even between 12 and 10 isn’t so bad. The trouble comes when you wait until it’s at 10 — and then the seeds go from 10 down to 7% almost immediately.
“If you’re not working on a contract where they have to be at 10% and you can put them in the bin with a little air, combining 12% seeds sure makes a lot of difference [in terms of reducing fire risk],” he continues. “And it’s much easier to clean up; you don’t have so many of those little pieces in your grain tank.”
Todd, who farms near Onida, says the biggest problem he’s encountered with fines on his John Deere combines is that they’ll accumulate on the intake screen. The engine draws them back, and they sail toward the manifold and muffler. “Then they stick, and you start building up that material. It gets hot, falls off — and starts fires.”
The Sully County producer recalls one week during the 2007 harvest when the humidity was below 25%. They had fires every day up until about 5:00 p.m., when temperatures started to drop. “I’d clean off the combine two or three times a day,” Todd recounts. “Then we’d slow the machines to keep the exhaust temperature down.
“If you’re running a grain cart, the exhaust temperature will get even higher because you’re never shutting off [the combine]. Just slowing down and not pushing the engine so hard will help a lot.”
For Todd, cleaning the combine means blowing off the fines with an air hose. However, “if a fire does start or there are little ‘glows,’ we’ll usually soak them down first to get the flames off,” he explains. “If you just blow them around, you’ll start fires everywhere.” Once the mass of fines is wet enough to no longer burn, he’ll go ahead and blow them off.
The combine always has a fire extinguisher on board. “Sometimes we’ll also carry a small garden sprayer,” Todd notes.
Some of his neighbors have installed gauges to monitor the combine exhaust temperature. Once that temperature gets to a certain level ,the operator slows down so the engine isn’t working as hard. While he hasn’t employed an exhaust temperature gauge on his own combines, “last year we painted the exhaust and mufflers with a special silver paint, and that helped,” Todd says. “It made the manifold and muffler more slippery, so the dust didn’t stick as much.”