by Sally Colby
While only two percent of the population is involved in farming, injury and fatality statistics indicate it is the most dangerous industry.
Dan Neenan, National Education Center for Agricultural Safety, discussed the hazards of working in grain bins, which are considered a confined space, and how farmers can avoid entrapment.
“A confined space is large enough and so configured that an employee can enter and perform work, has limited means of ingress and egress, and is not designed for continuous human occupancy,” said Neenan. Potential hazards in confined spaces include oxygen deficiency, flammability, temperature extremes, falling objects and slick or wet surfaces.
Neenan described the most common, most fatal grain bin incident. “When the auger is turned on, it pulls grain straight down,” he said. “The human, being the heaviest thing in there, is pulled straight down as well. If rescuers go in at this point, there’s potential for them to push the grain over the mouth and nose of the person trapped. If you get into a bin with a 10-inch auger running, flowing grain can pull you to your waist in 15 seconds and completely submerge you in 30 seconds.”
Another cause of grain bin entrapment occurs after grain with high moisture content freezes. “We fill the bin from the top and feed it out from the bottom,” said Neenan. “When it gets really cold, that top six or seven inches might crust, and as we feed out from the bottom, it creates a void. That void area could be three feet deep or 30 feet deep. If someone walks over it, it can’t support their weight and they fall down through.” In addition to being trapped in the grain, the worker is potentially injured from the fall. Any rescuers entering can cause more crusted grain to fall on the person.
Grain bin accidents also occur when grain stops coming out of the bin. The farmer goes in, thinking the bin is empty, and sees grain piled up around the sides. “They take a pole or a shovel and try to knock it loose,” said Neenan. “As they knock it loose, the grain avalanches down around them.”
While the thought process used to be ‘let’s go in and yank him up out of the grain,’ removing someone from a bin is a difficult procedure. It’s nearly impossible for anyone to conduct the operation successfully without specialized equipment, and the entrapped person has a much greater chance of survival if trained personnel are called immediately to conduct the rescue.
To illustrate how quickly a grain bin can become a death trap, Neenan explains that if a 165-pound person is trapped to their waist, 325 pounds of pressure is required to pull the person up and out of that space. “If two people go in and there’s already 325 pounds of pressure on somebody trapped in the grain and the two people are standing on the grain, they’re going to sink as they’re pulling him out,” he said. “If someone is trapped to their neck, it’s 625 pounds of pressure. If you put 625 pounds of pressure on somebody’s arm, it’ll pull the arm out of the socket.”
Several measures help ensure safety for farmers entering a grain bin. “Entering a confined space is a two-person job,” said Neenan, noting that this is the rule most often broken. “The person entering the space, and there has to be a reliable attendant outside watching what’s going on. If that person (inside the bin) becomes trapped or unresponsive, the attendant’s job is not to go in after him, but to stay out and call for emergency services.”
The attendant should have a fully charged cell phone with reliable reception, and should know the physical address of the farm. If the bin isn’t easily visible from the road, the attendant should be able to clearly describe the bin’s precise location and guide first responders to it.
The person entering the grain bin should have a chest or full-body harness. Neenan said another option is a boatswain’s chair with a retrieval line attached. Harnesses should fit snugly, and the person should be familiar with where to tie off.
Air quality sampling with a gas monitor prior to entry and throughout the time someone is in the bin is essential to ensure a supply of 19.5% oxygen. “With air monitors, turn them on and calibrate them first in fresh air before going into the bin where there could be potentially bad air,” said Neenan. “We need to calibrate that because the LEL (Lower Explosive Limit) is based on oxygen content. If the oxygen level is less than 19.5%, or if combustible gas or vapor is detected in excess of 10% of the lower flammable limit, we need to ventilate that space.” Neenan recommends ventilating for an hour, then re-testing.
A suitable gas monitor measures oxygen content, percent LEL, carbon monoxide and hydrogen sulfide. “Make sure there’s good oxygen content to start with,” said Neenan. “Otherwise the reading for the LEL will be incorrect.” Neenan added that monitors might have a slight delay in read out, which means if the alarm sounds, oxygen levels may have already been decreasing for five to 10 seconds.
Neenan said most of the dangerous gasses in a grain bin are heavier than air and settle in the lower part of the bin. Readings should be taken at several levels to determine gas levels throughout the bin. For the most accurate real-time readings, Neenan suggests clipping the gas monitor to the entrant’s harness.
Power sources should be clearly labeled and easy to locate so responders can quickly turn off an auger, turn on a fan and regulate other electrical equipment. A lockout/tagout system for the grain bin auger and all other moving parts helps prevent serious injury. Neenan said lockout/tagout kits for power sources are not expensive and easy to use, so there’s no excuse for not having them.
Conditions that make grain bin entry even more risky include extreme temperatures. If the weather has been hot, the bin will be hotter inside, and PPE can lead to rapid overheating. Neenan suggests taking plenty of breaks and maintaining hydration with water.
Following these recommendations greatly reduces the risk of someone being seriously injured or dying in a grain bin accident. “Proper planning and training for confined space entry can mean the difference between coming back out or not,” said Neenan.