For anyone who works with grain in storage bins, loading, unloading and moving it, take time to recognize the hazards of flowing grain and how to prevent a grain entrapment situation, advises Dick Nicolai, agricultural engineer at South Dakota State University (SDSU).

There are three ways to become trapped in grain: in flowing grain, the collapse of bridged grain, and the collapse of a vertical wall of grain.

Flowing Grain Hazard

“When a grain bin is unloaded, the grain flows downward from the top center, creating a funnel effect where the grain is leaving the bin,” Nicolai explains. “Entrapment can occur quickly as an unloading auger draws grain forming a surface cone.

“It takes less than three seconds for a person inside the bin to become helpless in flowing grain, which acts like quicksand, and will pull a worker under the grain and cause suffocation,” he warns.

Crusted Grain Hazard

When grain kernels are moldy, high in moisture content, or in poor condition, they stick together and form a crust. A hollow area can form below the crust when some of the grain is first removed; the crust remains because it is self-supporting.

“This gives a false indication that it is safe to stand on the surface of the grain, but it will usually collapse and instantly bury anyone walking on the crust in the hollow cavity,” he cautions.

Vertical Grain Wall Hazard

When stored in poor condition, grain can also form large, vertical columns against the bin wall, Nicolai points out. When a worker tries to dislodge the grain from the bottom, it can collapse and produce an avalanche of grain down on the worker. Without warning, when the grain breaks loose, individuals working at the bottom of the grain wall can be buried almost instantly.

If secondary avalanches are possible, this can make it very risky for rescue personnel to dig out the worker. The rest of the grain must be stabilized or knocked down to make it safe for rescue personnel to work, he suggests.

Safety Points

  • Never enter a grain storage structure when it is being loaded or unloaded, Nicolai stresses.

  • Always use a safety harness with a safety line and two observers during any grain bin entry (Figure 1).

  • Never enter a grain bin alone; have at least two people at the bin site to assist in case problems arise.

  • Use a wooden pole or weighted line to break up surface crusts in the grain while remaining on the outside of the bin.

  • Never enter a storage structure that has a crust and do not walk on a surface crust.

  • Work above the vertical grain wall and stay above the highest part of the wall.

  • Use a body harness and safety rope, tied off securely, for workers who break vertical columns of grain sticking to the sides of grain bins.

  • Keep the workers using the harness close to the surface of the grain to prevent the need for extreme force during a possible grain entrapment.

  • A person buried up to his or her shoulders in grain will require a force equal to almost four to five times their weight to be removed. For instance, a 150-lb. person will require up to 750 lb. of pull to be removed. Such a force may result in spinal injury.

  • Install a permanent ladder on the inside of all grain bins for workers to use for emergency entry and exit.

  • Secure all grain storage areas to prevent unauthorized entry.

  • All external grain bin access ladders must be raised above the ground to a height that is inaccessible to children.

  • All workers, family members and visitors should be warned about the dangers of flowing grain.

  • Place warning decals on all bin entrances and gravity wagons.

  • Manage grain to avoid conditions that cause spoilage and bridging.