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Grain dust explosions: K-State grain scientist discusses causes, precautions

Several factors must be present for a grain dust explosion to occur. Removing any of those factors reduces the likelihood of a grain dust explosion. The highest frequency of grain dust explosions occurred in the late 1970s and early 1980s.  

In the aftermath of an Oct. 29 grain elevator explosion in Atchison, Kan., that claimed six lives and injured two others, Kansas State University grain scientist, Leland McKinney said that while grain and other kinds of dust can be dangerous, steps can be taken to reduce risk.

“It’s a real tragedy. Our thoughts and prayers go out to the people who are affected by this,” he said.

McKinney answered questions relating to grain dust explosions.

Q. Why do explosions happen sometimes in grain storage facilities?

McKinney: Several factors must be present for a grain dust explosion to occur. They all have to be present at the same time. These conditions are: 1) an ignition source, such as a hot bearing, welding or cutting; 2) an adequate concentration of low moisture grain dust; 3) the grain dust is in suspension; 4) the presence of oxygen; and 5) the ignition of the grain dust in an enclosure, such as an elevator.

Removing any of those factors reduces the likelihood of a grain dust explosion.

Q. What can grain storage facilities do to minimize the risk of explosions?

McKinney: Grain storage facilities can reduce the risk of a grain dust explosion with good housekeeping practices to reduce grain dust levels and by installing monitoring devices on equipment to detect overheating of bearings.

Most primary explosions occur in a bucket elevator (leg). For that reason, modern facilities are designed with the leg on the outside of the facility in order to reduce risk. Older facilities were built with the leg inside.

The cleanliness of the facility is also a factor. Most of the destruction in a grain dust explosion is caused by secondary explosions, or a series of explosions, that occur through the facility. It’s important that grain elevators have a good housekeeping program so that they keep the concentration of dust down and be very aware of any points where ignition may occur.

OSHA (Occupational Safety and Health Administration) has recognized that this (grain dust) is a potential workplace hazard, and has grain handling standards in the regulations that address precautions that need to be taken. They address cleanliness of the facility and other hazards that occur in grain handling facilities.

Q. Do these kinds of explosions happen often?

McKinney: During the 10-year period 1995 to 2005, an average of 10.5 explosions occurred per year, according to statistics compiled by Robert Schoeff, professor emeritus here at K-State. He is now retired, but he devoted a major portion of his career toward collecting statistics and finding out why grain dust explosions occur. He was an internationally-recognized expert on the subject and his work resulted in a sharp decline in the number of explosions annually. That work included annual reports from 1980 to 2005 (K-State Research and Extension website:

Q. Are we seeing more grain storage facility explosions than we used to?

McKinney: The highest frequency of grain dust explosions occurred in the late 1970s and early 1980s.  A lot of fact finding went on at that time.

Grain type not an issue

Q. Does it make a difference what kind of grain is stored?

McKinney: All grain dust can be explosive given the conditions described earlier are met. Other kinds of dust can be explosive. I believe it was in 2009 that a sugar mill that exploded in Georgia. Other kinds of dust, when suspended and with a source of ignition, can cause a fire or an explosion.

Q. Does low atmospheric humidity cause dust explosions?

McKinney: There’s no data that indicate that low atmospheric humidity causes dust explosions.

Q. Can high atmospheric humidity prevent dust explosions?

McKinney: There’s also no data that indicate that high atmospheric humidity prevents dust explosions.

Q. Is there more danger of an explosion in one type of construction – wood, steel or concrete – compared to others?

McKinney: No, there is no evidence to support that the type of construction makes a difference in grain dust explosions.

Q. Could this kind of accident happen in smaller, on-farm grain handling facilities?

McKinney: I would say any time you have a situation where you have an ignition source and grain dust, there’s the potential for a flash fire or an explosion.

“You have to stay on top of your maintenance and housekeeping and always have safety on your mind in whatever industry you’re in,” McKinney said.

Information about grain processing, including how to obtain a video, “Deadly Dust,” is available on the K-State Department of Grain Science and Industry website:

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