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Combine Fires: Research, Experience & Commercially Available Products

Tuesday, August 27, 2019
filed under: Harvest/Storage

Dan Humburg
     Eight years ago, ag engineer Dan Humburg had no experience with sunflower. But when the South Dakota Oilseeds Council asked researchers at South Dakota State University to study the issue of combine fires during sunflower harvest, Humburg dove right in.
       “We’ll research anything you give us money to research,” Humburg joked during his presentation at the 2019 NSA Summer Seminar in Medora in June. 
       In 2012, Humburg and his team at SDSU began a study on preventing combine fires. The study, funded by the S.D. Oilseeds Council and the National Sunflower Association, had three main objectives: (1) to understand the basic characteristics of sunflower dust in the lab; (2) to see it in action in the field and how it interacts with different areas of the combine; and (3) to bring data together to suggest potential engineering solutions that could serve to change or interrupt one or more of the factors present when a harvest fire starts. 
       What Humburg and his team learned in their years of research, prototypes and field tests resulted in a product now available to producers that helps reduce the risk of combine fires.  “FireStop” is a patented system that separates volatile dust from the ignition source.  It keeps the air around the exhaust system clean, thereby preventing the entry of dust that would otherwise ignite on the hot engine exhaust system.
       “All of our lab work points to the pith in the crop stem as the material that collects on the combine, and is most likely the material that ignites first,” Humburg explained.  “This. of course, was not a revelation to sunflower producers.  Sunflower pith has certain characteristics that set it apart. It is extremely light and hangs in the air like a cloud. Sunflower pith is made up of very small particles, which means it easily goes through screens and radiators. Those particles have a very large pore space and are sponge-like with a large surface area.  That large surface area makes the material very reactive, and tests show this dust ignites at relatively low temperatures, much lower than soybean, wheat and corn dust.”
       All that research led Humburg and his team to designing and building a hardware system that is added to the combine and prevents the ignition of volatile aerosol dust near hot exhaust components.  Humburg built the systems and tested them on a variety of combines. In 2013, he installed three systems for producers.  In 2018, he installed 20 systems on machines across North and South Dakota and Minnesota. 
       “As you know, a lot of farmers are reluctant to grow sunflower because of the risk of fires.  But many who are using this system have told me they no longer experience chronic fires, and the stress of harvest is greatly reduced.  It is a different experience when you’re not sniffing the wind, expecting a fire,” said Humburg.  
       “I will never tell someone to stop cleaning their combine; but those with this system installed tell me they spend less time cleaning their machines.  Now they can clean them once a day, where before one producer told me he had been stopping every two rounds to blow off their combines — and they still had fires.” 
       Humburg is quick to point out there is always a risk of fires, and producers should be vigilant in monitoring their machines.  And he adds, as with any piece of machinery, there are always things that can go wrong. 
       “For example, we found that in one case the fan impellor could shift and stop the motor.  The kits are now protected with a bypass relief, and I now apply Loctite to the parts to prevent movement.  The motor seal could fail, so all kits now have a case drain,” he said.  “A mouse could build a nest inside the box, so I’d suggest putting a repellant nearby in the off-season.”
       But he said, the benefits are still significant.  Kits are available for a number of combine models and can be adapted to many machines.  He said designs for other models could happen if there is demand and time.  Humburg noted that since 2014, John Deere has included a similar system on their combines to protect the diesel particulate filter. 
       The 2019 price of a FireStop kit is $4,950 plus tax and freight. Humburg says kits should be ordered at least two months prior to sunflower harvest, as parts of the kits have long lead times to manufacture.                 
       To learn more about the kits and specific models, or to place an order, visit  Information on experience specific to different models is available there, too. Humburg is also working on producing instructional videos to show producers how to install the kits themselves.
— Jody Kerzman
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