Charles
V. Schwab, Mark Hanna, and Laura
Miller
Iowa State University Extension
Millions
of bushels of grains safely flow from field to storage during
harvest each year. However, one person trapped beneath the
surface of the grain can stop the flow in a matter of seconds.
All too often, farm workers or family members suffocate beneath
the surface of grain. In Iowa, newspaper accounts show that
this tragedy is repeated several times a year. The real tragedy
is that many who have experienced this type of accident did
not know the potential danger of handling grain.
Grain
handling accidents happen very quickly. Flowing grain can draw
in a person within five seconds. That time is decreased with
the use of high capacity unloading equipment, such as large
wagons emptied quickly with large augers or legs. As farm equipment
becomes faster, humans have less time to respond before they
are helpless to the effects of flowing grain.
For
example, a high capacity conveyor can move 5,000 bushels of
grain an hour. At that rate, a 6-foot tall person would become
submerged in only 15 seconds.
Children
are at an even greater risk around flowing grain. They are
shorter and become submerged quicker than adults. They also
do not have the physical strength to pull themselves out of
grain before they become entrapped.
A
grain surface may appear solid, but it is not. A small opening
in the unloading gate gives the entire surface the quality of
quicksand. When a single kernel is removed from the bottom of
a wagon, kernels directly above it rush to fill the void, creating
a fluid motion. Flowing grain is like a fluid; objects on the
surface sink, and heavy objects sink faster than light ones.
Even
if grain has stopped flowing, submerged objects or people
are difficult to extract. Victims with tremendous upper body
strength cannot pull themselves out if they are buried up
to the chest. The force required to remove someone buried
in grain can easily exceed 2,000 pounds, which is about the
same as lifting a small car.
You
can test your own strength against the force of grain. As
an experiment, fill a large container such as a livestock
watering trough with grain. Tie a rope to a plywood disk 2
feet in diameter, about the same diameter as a human body.
Bury the disk in the grain at the bottom of the container,
leaving the end of the rope above the grain surface. Then
try to pull out the disk with the rope. It requires more force
to pull out a 180-pound person than a wooden disk.
One
devastating example of that force occurred when a man was
submerged in grain up to his neck. Rescuers believed ropes
would keep him from sinking farther into the grain while they
emptied the rest of it from the bottom of the bin. However,
the force on the rope was so great that two men could not
hold the man's head above the grain. He was buried deeper
and suffocated before the grain was removed.
Suffocation
occurs in several ways during grain-handling accidents. Investigations
reveal that some victims ingest grain. During submersion, grain
will flow into voids and openings, such as the mouth or nostrils.
In some cases, grain has been found in victims' stomach, lungs,
and throat.
Suffocation
also occurs when the victim is no longer able to inhale air.
Pressure in a grain mass can restrict a person's ability to
breathe. This happens when the chest cavity and diaphragm
shrinks as a person exhales, and grain quickly flows around
the body, filling any areas that are voids. On the next breath,
the person will have less room to expand the chest cavity
and inhale air. This is similar to the way a python strangles
its prey. Panic hastens the process, and as the capacity of
each breath becomes smaller, the person is unable to inhale
enough air to survive.
Another
factor is lack of a breathable atmosphere in the grain. Typically,
a person requires a specific volume of air. In a grain-handling
accident, grain restricts the air flow to the area surrounding
the submerged person. As the person uses oxygen and exhales
carbon dioxide, the air surrounding the person is depleted
of its oxygen.
The
easiest way to reduce risk is to eliminate the situation. Make
it a policy to always lock all access doors to grain storage
structures. With this policy, children are not exposed to suffocation
hazards in bins.
Farm
workers, however, must expose themselves to some suffocation
risks. To reduce risk, follow these guidelines:
- Lock
out power to all types of grain-handling equipment. Disconnect
power and place locks over operating switches. This also
helps discourage grain theft.
- Always
use the buddy system when you are unloading or loading grain.
Notify a second person of your whereabouts at all times
and who can obtain help if needed.
- Never
permit children to ride in grain wagons or enter grain storage
areas.
If someone
is caught in flowing grain, there are several ways of handling
the situation. The action required depends whether the person
is in a wagon, grain bin, or other type of storage structure.
Check other references for specific rescue procedures.
Farm
workers seldom have the strength or reaction time to save
themselves once they are trapped in flowing grain. However,
all farm workers can recognize the dangers of flowing grain,
and avoid taking risks in routine tasks.
How
Much Do You Know?
Farm operators often overlook dangers associated with handling grain. Test your knowledge with this quiz.
- How
long does it take for someone to become helplessly trapped
in flowing grain?
- less
than 6 seconds
- less
than 60 seconds
- more
than 60 seconds
- How
much physical force is required to pull out a person buried
below the surface of grain?
- less
than 400 lb.
- between
400 and 1,000 lb.
- more
than 1,000 lb.
- Identify
possible way(s) a person can suffocate in grain. the chest
is constricted, breathing is difficult
- grain
fills lungs and air passages
- lack
of breathable air surrounding a person
- all
of the above
- Children
never can safely ride in grain wagons.
True or false?
See
answers at the end of this document.
What Can You Do?
The
best way to prevent grain suffocation hazards is to avoid dangerous
situations.
- Apply
suffocation hazard decals to all grain wagons, grain bins,
and grain storage structures.
- Lock
access doors to grain bins; limit access to the top of grain
wagons.
- Instruct
everyone who operates grain wagons or grain handling equipment
about potential suffocation hazards.
- Make
a commitment to always have an extra person present when
you must be in an area where there is a potential grain
suffocation hazard.
This
publication covers only some aspects of grain suffocation hazards.
For more information about harvest safety, contact your local
Extension office, or check these publications:
Don't
Drown in a Grain Wagon, Pm-1334a, and Suffocation Hazards
Associated with Stored Grain, Pm-1293i, available through
Extension.
For
a grain wagon suffocation hazard demonstration and safety
decals, contact Farm Safety 4 Just Kids at 130 East First
Street, Earlham, Iowa 50072. Telephone (515) 758-282.
Answers
to quiz: 1-a; 2-c; 3-d; 4-True
Disclaimer
and Reproduction Information: Information in NASD does not
represent NIOSH policy. Information included in NASD appears
by permission of the author and/or copyright holder. More
NASD Review: 04/2002
This
document is Fact Sheet
Pm-1265i
,
a series of the Safe Farm Program, Iowa State University Extension,
Ames, Iowa. Safe Farm promotes health and safety in agriculture.
It is funded by the National Institute for Occupational Safety
and Health, Iowa State University, and a network of groups
that serve Iowa farm workers and their families. Publication
date: September 1992.
Prepared
by Charles V. Schwab, Extension safety specialist; Mark Hanna,
Extension agricultural engineer; and Laura Miller, Extension
communications, Iowa State University Extension, Ames, Iowa.
Cooperative
Extension Service, Iowa State University of Science and Technology
and the United States Department of Agriculture cooperating.
Robert M. Anderson, Jr., director, Ames, Iowa. Distributed
in furtherance of the Acts of Congress of May 8 and June 30,
1914. The Iowa Cooperative Extension Service's programs and
policies are consistent with pertinent federal and state laws
and regulations on nondiscrimination regarding race, color,
national origin, religion, sex, age and handicap.
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