Entrapment Risks due to Flowing Grain


Use the following format to cite this article:

Entrapment risks due to flowing grain. (2021) Ag Safety and Health eXtension Community of Practice. Retrieved from https://ag-safety.extension.org/entrapment-risk-due-to-flowing-grain/.

Farmers and ranchers use bins to dry and store grain and to feed their livestock. For the most part, augers are used to transfer the grain to and from bins. Some machinery and augers now used in production agriculture have increased in size and power, resulting in less time for farmers and ranchers to react in dangerous situations. It is therefore important to understand fully the hazards and risks associated with flowing grain and to follow safety guidelines to avoid a potentially fatal injury incident. There are four main situations that pose entrapment risks when you work with stored grain: flowing grain, grain bridge collapse, grain wall avalanche, and use of a grain vacuum. Each of these situations and its entrapment risks are described below.

Flowing Grain

Grain Bin with Flowing Corn

(Source: Pennsylvania State University. Agricultural Safety and Health)

An auger is used to move grain from the bottom center to the outer edge of a grain bin, and from there into a vehicle or alternative storage area. As the grain flows, it forms a funnel, with the wide mouth of the funnel at the top and a smaller opening at the bottom, as shown in the diagram above. If you are in the bin when the grain is being unloaded, you can quickly become engulfed in grain. Depending on the size of the auger, you can be trapped in grain up to your waist within 10 seconds and completely submerged within 25 seconds. Once you are submerged in grain, it can take over 1,000 lb. of force to free your body.

Grain Bridge Collapse

Farmer on Moldy Corn Bridge

(Source: Pennsylvania State University. Agricultural Safety and Health)

A grain bridge forms when grain in poor condition exists throughout a bin. Cavities or pockets of loose grain can form under the crusted level when the auger begins to unload grain from the bin. Grain bridges are not stable, and if you are standing on top of a grain bridge when it collapses, you can quickly become entrapped in the grain. Once you fall through the grain bridge and are trapped, it may be difficult to locate you because the grain will flow rapidly into the area around you.

The proper way to break up or remove a grain bridge is to use a long pole inserted through an access hole from outside the grain bin.

Grain Wall Avalanche

Farmer in Bin with Corn

(Source: Pennsylvania State University. Agricultural Safety and Health)

Moldy or frozen grain can cling to the side of a grain bin, as shown in the diagram above. A grain avalanche can occur when you are breaking up crusted grain from within a bin and the grain wall is higher than you. The grain wall can collapse, creating an avalanche that can quickly engulf you, causing injury or death.

If you must enter a bin, use a body harness and a safety line that is securely tied off. Work above the vertical grain wall, staying above its highest point.

Use of a Grain Vacuum

Grain vacuums are being used with higher frequency as a means of moving grain rapidly from older bins with smaller unloading augers, bins in remote locations without augers, and bins that have mechanical problems. Powered by a tractor power take-off, electricity, or an external motor, these vacuums have the capacity to move several thousand bushels of grain an hour. Typically, an operator uses the vacuum inside the bin, moving the nozzle in a sweeping motion. During the last few years, several operators have been killed when using the equipment in this manner. If the operator drops or releases the nozzle, it can quickly become buried in grain. As a result, the operator may try to lift the nozzle while the vacuum is running. This can cause the grain to be sucked out from under the operator, burying him or her in seconds.

Below are two videos that demonstrate the use of a grain vacuum. To view a grain vacuum in use within a bin, click on the video below.

To see a grain vacuum transferring grain into a truck, click on the video below.

Suffocation in Grain Bins

Flowing grain is similar to quicksand and can quickly engulf you, resulting in suffocation. When even a small amount of grain has space to move, it quickly fills in that new area. When you are trapped by grain and exhale to breathe, the grain flows into the space created by the movement of your chest, placing pressure on your chest and reducing the space that your lungs have to expand during your next inhalation. Each time you exhale a breath, the space around your chest decreases, eventually causing you to suffocate as you take smaller and smaller breaths (or shallower and shallower). When you are trapped in flowing grain, you can also suffocate from taking grain particles into your lungs, stomach, and throat.

Entrapment in Grain Transport Vehicles

Entrapment incidents can occur in grain transport vehicles that are used to move grain from one location to another. The most common types of grain transport vehicles are gravity wagons and bulk material semitrailers. Entrapment in these vehicles is similar to entrapment in a grain bin: a quicksand effect can occur during the loading or unloading process.

Safety Recommendations

  • Lock all access doors to grain storage structures.
  • Secure grain bin ladders and doors to prevent unauthorized entry, especially by children.
  • Never allow children to play or ride in grain wagons. Most grain entrapment incidents in on-farm transport vehicles involve children.
  • Apply entrapment warning decals to all grain bins, wagons, and grain storage areas, as well as commercial transport vehicles.
  • Never work alone! When working with others during grain unloading, know where each person is located and what he or she is doing.
  • Warn workers, family members, and visitors about the dangers of flowing grain and the risk of entrapment.
  • Establish a nonverbal communication system with others when working around flowing grain because of the excessive equipment noise levels.
  • When possible, use inspection holes and grain bin level markers rather than physically entering a grain bin.
  • Before entering the grain bin, lock out and tag out all power controls to unloading augers and conveyors.
  • If you must enter the grain bin, wear a body harness with a lifeline secured to the outside of the bin, and have at least one other person observing your work activity in the bin.
  • When cleaning a grain bin, always work from top to bottom.

Use the following format to cite this article:

Entrapment risks due to flowing grain. (2021) Ag Safety and Health eXtension Community of Practice. Retrieved from https://ag-safety.extension.org/entrapment-risk-due-to-flowing-grain/.


LaPrade, J. (2008) Grain bin hazards and safety considerations. Alabama Cooperative Extension System. Retrieved from https://store.aces.edu/(S(wgo00aqtzi1ami55t4ckx255))/ItemDetail.aspx?ProductID=16178&SeriesCode=&CategoryID=144&Keyword=&cn-reloaded=1.

Schwab, C., Hanna, M. & Miller, L. (2004) Handle your grain harvest with care. Iowa State University Extension and Outreach. Retrieved from https://store.extension.iastate.edu/ItemDetail.aspx?ProductID=4614.

Grain bin hazards. (2019). Ohio State University Extension Agricultural Tailgate Safety Training. Retrieved from https://ohioline.osu.edu/factsheet/aex-59155.

Yoder, A., Murphy, D. & Hilton, J. (2003). Hazards of flowing grain. Pennsylvania State University College of Agricultural Sciences Cooperative Extension. Retrieved from https://extension.psu.edu/hazards-of-flowing-grain.

Reviewers, Contributors, and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
LaMar Grafft, East Carolina University grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University Has since retired
Dennis J. Murphy, Pennsylvania State University – Has since retired
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu