Nov. 4, 2011

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 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. grain dust is that's 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 their risk of a grain dust explosion by using 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. Managers should be very aware of any points where ignition may occur.

OSHA (Occupational Safety and Health Administration) has recognized that grain dust is a potential workplace hazard, and has grain handling
standards that include precautionary measures. They address cleanliness and hazards of grain handling facilities.

Q: Do these kinds of explosions happen often?

McKinney: During the 10-year period 1995-2005, there was an average of 10.5 explosions 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

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.

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, there was a sugar mill that exploded in Georgia. Other kinds of dust, when suspended and there’s 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,” the grain scientist 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: www.grains.ksu.edu.

Mary Lou Peter
Kansas State University News Release