Handling stored grain safely
May 01, 1998
by Teresa Acklin
Understanding the dangers and following safety guidelines can prevent injury and death.
Handling and managing grain in storage is filled with hazards that can cause injuries and often death: getting caught in augers and power take-off shafts, suffocation, overexertion, falls, exposure to dust and/or chemicals, electrocution, fires and explosions. Facility operators must know how to take the necessary steps to protect workers from these dangers.
1. Getting caught in augers or power take-offs. Open augers are extremely dangerous and only invite trouble. Augers should have protective screens or covers placed on them at all times.
Trash should not be removed from an auger while it is running. And the power should be disconnected when an auger is serviced. The power take-off should have a protective shield. Loose clothing that can get caught in machinery should not be worn.
2. Falls. Next to automobile accidents, falls kill more people in the United States each year than any other accident. Grain storage operators can lessen this number with a few simple precautions.
First, outside ladders should be secure. For heights over 6 meters, a cage or other approved safety device should be used on ladders that are used for ascending or descending. Tools should be raised or lowered using a rope and/or basket never carried while climbing a vertical ladder. Extra care should be taken when climbing ladders and walking on wet or icy grain bin roofs.
3. Electrocution. In recent years, too many fatalities have occurred from portable augers striking overhead power lines. Look up and live!
When a person samples a bin or attempts to break up a bridge or hang-up problem, a simple check for power lines within reach of the metal probe or pipe should be made. This safety precaution can save a life. Storage site wiring should be done by a qualified electrician to insure proper grounding. Ground fault circuit interrupters are recommended.
4. Suffocation. The most common suffocation accident is entrapment and suffocation caused when a person is drawn under flowing grain.
When a grain bin is emptied, the grain flows in a funnel-shaped path above the outlet. If the outlet is located in the center of the bin bottom, the grain flows down the center. Speed increases as grain flows from the bin wall at the top of the grain mass into a small vertical column at the center of the bin. This vertical column of grain flows down through the grain mass at nearly the same rate as the grain is withdrawn from the bin.
Entrapment is similar to being drawn into quicksand. Once trapped in flowing grain, the victim is drawn rapidly to the bottom of the bin where he may become entangled in the unloading auger.
Near the center of the inverted cone, it takes only a few seconds to be drawn into the grain above knee depth. At that depth, with nothing to hold onto and nothing to push on but flowing grain, a person is trapped. If an auger moves about 90 cubic meters of grain per hour and the body volume of a person is about 0.2 cubic meters, a victim can be completely submerged in eight seconds or less. Larger unloading equipment decreases the time until submersion.
Similar accidents have occurred in gravity unloading grain wagons. Stay out of grain wagons or trucks during unloading.
The few survivors of this kind of engulfment said they covered their mouths and noses with their hands and didn't panic. They also expressed amazement at the tremendous speed at which they found themselves buried under the grain.
The condition of the grain apparently plays a major role in the survival of someone completely submerged. Someone buried in spoiled grain may have a greater chance of surviving because caked masses of grain form open air pockets and reduce the grain pressure on the body.
Another type of suffocation can occur when grain has spoiled in storage. Spoiled grain can crust over and a cavity will develop under the crusted surface as grain is removed from the bin. A person walking on the crusted surface could break through, become submerged in the grain and suffocate.
Spoiled grain also can cake in large vertical masses on bin walls, as seen in Figure 3 on page 28. Thus, when a person tries to break the caked material loose from below, large sections of grain can break off and cover the person in the bin. This risk increases as the capacity and particularly the height of the bin increases. Grain stored in large piles or bunkers also poses this type of hazard during load-out.
Spoiling grain also produces carbon dioxide as a by-product of fermentation. Since carbon dioxide is heavier than air, air is pushed out of the bin, resulting in an oxygen-deficient atmosphere.
If a person enters a bin or pit with carbon dioxide present, the carbon dioxide will overload the bloodstream and slow down breathing, which in turn can cause drowsiness, headaches and even death. Since carbon dioxide is colorless and odorless, no warning is given.
Some precautions can be taken to prevent suffocation and other hazards. A key rule to remember is “never enter a grain bin alone.”
Do not enter a bin when grain is being removed. The discharge system should be shut off and locked out before a bin with grain is entered.
Establish a method of communication with someone outside the bin. Shouting directions to another individual is not a dependable communication method. Equipment noise can block commands or cries for action or assistance. The other person may also become excited and fall or panic when trying to help.
It is dangerous to enter a bin that has had grain removed. Don't enter a bin without knowing whether any grain has been removed especially if crusting is evident. If a crust must be broken, a person should do so from the roof, using a wooden pole or weights attached to a rope.
If a bin with evident or potential danger must be entered, a rope and a safety harness similar to a parachute harness should be used with the rope tied off so it cannot slip from a helper's hand. Two people capable of lifting the third person out should be outside the bin. If necessary, one person can go for help.
The friction or drag on a body submerged in grain is tremendous, as every square centimeter of the submerged body is in contact with the grain. A person waist deep or deeper in flowing grain cannot be pulled from the grain by a rope looped under the armpits without causing severe injuries.
A person trapped in a bin but not buried has one option. That option is to walk the grain down by staying near the outside wall and keeping on the move until the bin empties or the flow can be stopped. Avoid the center of the cone.
A person who becomes trapped and is being sucked under the grain should cup the hands in front of the face, which will prevent grain from entering the respiratory tract and blocking air flow. This, coupled with staying calm and shallow breathing, may prevent immediate suffocation.
Some grains such as flax or millet will not support a person's weight. Therefore, walking across the surface of these grains or other unknown materials without testing to determine whether they will support the weight is dangerous.
If a bin must be entered to dislodge materials adhering to the side, it should be done from a position above the grain with two other people outside the bin. The grain bin should be entered from the top and the material dislodged as the first person is lowered into the bin. A boatswain's chair and a parachute-type safety harness with a 2-cm manila rope or equivalent lifeline attached should be used.
If a person from a position below the lodged material attempts to loosen it, the material can break loose quickly and bury him. Likewise, standing on bridged grain or chunks adhering to the walls can cause them to collapse and bury a person under the heavy weight of the material.
If a person becomes submerged or trapped in grain, the rescuer should shut off the unloading system immediately. This will stop the victim from being pulled under further. If there is an aeration system, the rescuer should start it to move air through the grain. This will provide fresh air to the victim. Then call local emergency officials.
The most successful emergency rescue step is to cut large holes around the base of the bin approximately 1.5 meters above the base at four to eight evenly spaced locations. This will reduce the volume of grain from the bin in the shortest period of time.
Use an abrasive saw or cutting torch to cut the grain bin side walls. Fire departments should be called to extinguish smoldering fires that may develop in the cutting process.
If a person is only partially submerged, normally the most efficient and safest method to extricate the victim also is to cut four to eight holes evenly spaced at the ring level below the grain surface to remove the grain. If possible, a safety harness should be placed around the victim prior to removal of the grain, and two to four stabilizing lines connected to the harness should be attached to the bin wall. This allows for the grain to flow away from the victim. Once the grain has moved away from the victim, the person can be extricated through either the top of the bin or through one of the openings cut in the side of the bin.
Do not attempt a rescue in an oxygen-deficient atmosphere. Call the emergency team, which should have the training and equipment to do the job safely.
Grain dust can be a mixture of particles of grain, soil, plant material, fungi, bacteria, residues of agricultural chemicals and the excreta of insects, rodents and birds. The mixture varies with the type of grain, growing conditions and how it was harvested, stored and processed.
Spoiled grain is especially contaminated with dust and bacteria. These dusts can affect the respiratory tract in a variety of ways and can cause gastrointestinal problems, skin rashes and eye irritations.
Individuals may react quite differently to the same dust. Each person's work history, health status and smoking history is unique. Thus, some people may be quite sensitive to the dust while others may be able to withstand several exposures prior to becoming sensitized.
To help reduce and prevent allergic reactions, a person should wear adequate protective devices, such as dust masks or helmets, and ventilation to remove the dusts should be provided. Those sensitive to the dusts should not enter areas where the dusts exist. “One-strap” disposable dust masks are not nearly as effective as “two-strap” models. Two-strap models fit better and allow less air leakage.
A word of warning is necessary. The simple dust mask will not protect a person against fumigants or areas where there is an inadequate supply of oxygen. These masks will not filter out harmful poisons nor will they add oxygen when there is an area with high concentrations of carbon dioxide resulting from the deterioration of wet grain.
If the presence of carbon dioxide is suspected, do not enter the area. Opening manholes and all side door openings, supplemented by forced ventilation through the area, will help reduce the hazard. If ventilation is not possible, measure the oxygen concentration before entering. Do not enter if oxygen concentration in the area is less than 19.5%.
This article is based on a bulletin by James A. Kramer, extension assistant, agricultural safety, published by the Cooperative Extension Service, Kansas State University, U.S. A more detailed treatment of grain-handling safety, “Safety in Grain Elevators,” is available from the Cooperative Extension Service Distribution Office, Umberger Hall, Kansas State University, Manhattan, Kansas 66506, U.S. Cost is U.S.$5.00.Grain handling safety procedures
Grain-handling accidents can be reduced if you follow the appropriate safety rules. You and your workers need to be trained in routine work hazards. All must be instructed to follow correct procedures when handling and storing grain.
Keep these safety measures in mind when storing and handling grain.
Don't enter a bin of flowing grain.
Don't enter a bin to break a crust or remove a blockage when unloading equipment is running, whether or not grain is flowing. Restarted flow can trap you.
Before entering a bin or cleaning or repairing conveyors: lock out the control circuit on automatic unloading equipment, as on a wet holding bin; and flag the switch on manual equipment so someone else doesn't start it.
Don't enter a bin unless you know the nature of previous grain removal, especially if any crusting is evident.
Beware of walking on any surface crust.
Don't depend on a second person on the bin roof, on the ground, or at some remote point to start or stop equipment on your shouted instructions because: equipment noise can block out shouts for action or assistance; and that person may fall or over-exert in the panic and haste of getting off the bin or running to the control point.
Be wary and alert while working with grain that has gone out of condition molds or blocked flow can create cavities, cave-ins or crusting.
When entering a questionable bin or storage, have two outside and one inside workers. Attach a safety rope to the man in the bin with the two men outside capable of lifting him out without entering the bin. One man outside cannot do this and cannot go for help while giving first aid.
Always wear a respirator capable of filtering fine dust to work in obviously dusty-moldy grain. Never work in such conditions, even with protection, without a second person on safety standby.
If a grain bin is peaked close to the roof, be extremely cautious. Crawling between roof and peak can cave grain and block the exit.
Maintain proper and effective shields and guards on hazardous equipment.
Do not enter the bin when the presence of carbon dioxide is suspected.
Exercise caution when climbing on bins.
Grain center wiring should be done by a competent electrician.
Be aware of and avoid overhead power lines.
Be prepared for emergencies.
Have a rescue plan.