Hazards of Flowing Grain - Demonstration

Aligns with the following AFNR Standard(s): CS.03, PS.03, and PST.02.
Hazards of Flowing Grain - Demonstration - Articles


SAY Clearinghouse: Aligns with AFRN CS.03, PS.03 and PST.02.

Hazard Overview

Grain is dried and stored to feed livestock and augers are used to transfer the grain to and from bins. The four main situations that pose entrapment risks when working with stored grain include: 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

When grain flows, it forms a funnel, with the wide mouth of the funnel at the top and a smaller opening at the bottom. If you are in a 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

Forms when poor conditioned grain exits throughout a bin. Grain that becomes wet and moldy can stick together in large masses or chunks. If the grain becomes a solid mass on the top surface, the running of the auger may create a cavity below the surface. Grain bridges are not stable; therefore if you are standing on top of a grain bridge when it collapses, you can quickly become entrapped in the grain.

Grain Avalanche

When moldy or frozen grain clings to the side of a grain bin, a grain avalanche could 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.

Grain Vacuums

Grain vacuums are used to rapidly move grain 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, grain 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. Dropping or releasing the nozzle on the grain surface can quickly pull the nozzle down into the grain and become buried. 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, entrapping him or her in seconds.

Children love adventure and exploration which can sometimes lead them to "attractive nuisances". These are areas that appeal to children, but have a degree of danger such as swimming pools, farm ponds, unattended ladders, farm machinery, grain storage areas, animal pens and many more. Gravity flow wagons and grain bins are examples of attractive nuisances to children, and also present danger to adults. Grain flow can quickly entrap someone. Here is a demonstration that will reinforce how difficult it is to pull a victim to safety. The force needed is greater than a person realizes and without a rescue harness, the victim can be further injured.

Learning Objective for the Demonstration

To measure the force needed to pull a person out of a grain entrapment situation and to demonstrate that most farmers are not prepared to handle this type of emergency.

Materials Needed:

  • 5-gallon bucket
  • Shelled corn or small grain (wheat, oats, rye)
  • Cord or small rope (approximately 4 feet long)
  • A small barn scale
  • A 15 to 18 inch doll

Procedure and Key Discussion Points:

  1. Weigh the doll.
  2. Attach a cord around the doll's waist or chest (Note: This should never be done in a real life situation), or construct a cloth harness to place between doll's legs and around the waist and chest with a hook on the back at the shoulders.
  3. Place the doll in a bucket so that it is trapped up to his/her arm pits in the grain.
  4. Attach scales to cord or rescue harness and measure the pull needed to extract the doll from the entrapment. Key discussion point: discuss how pulling the doll from the bucket differs to pulling a person from a grain entrapment.
  5. Compare this force with the force needed to pull a 150 pound person from a grain entrapment (Use chart/formula (Figure 2) below for calculation).Key discussion point: Discuss with the group the amount of force need to extract the doll and whether the force was higher or lower than their expectation and why.

Demonstration Image

Figure 1 Depth vs. force for a 165 lb. adult

Take-home Points for the Demonstration

Participants should have a basic understanding of the following:

  • Reasons/scenarios for how a person can become entrapped in grain.
  • The amount of time it takes for a person to be trapped in grain.
  • Reasons why a person cannot be pulled out of grain.


We have provided a one page evaluation which has been designed to be used with participants after each lesson. The answer key is offered below.

Evaluation Questions Answer Key

  1. D
  2. B
  3. C
  4. (student response)
  5. (student response)


Entrapment risk due to flowing grain. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice.

Murphy, D. and Hill, D., (2014) Hazards of flowing grain . Penn State Extension.