Grain dryers serve an important role in preserving grain quality during storage, thereby protecting the commodity’s commercial value and reducing potential bin engulfment/entrapment hazards.
Although there are different types and designs of grain dryers, every dryer needs to be maintained and serviced according to the manufacturer’s recommendation and more frequently if necessary.
Given the potential for fires, the Occupational Safety and Health Administration’s (OSHA) Grain Handling Standard 29 CFR1910.272(p) (continuous-flow bulk raw grain dryers) requires direct-heat grain dryers to be equipped with automatic controls that:
• Will shut off the fuel supply in the event of power or flame failure or the interruption of air movement through the exhaust fan.
• Will stop the grain from being fed into the dryer if excessively hot temperatures occur in the exhaust of the drying section.
Grain Dryer Operations
Grain dryers operate at temperatures warmer than 140 degrees F to reduce the moisture content of grain and to enhance its storability. Common dryers are fueled by natural gas, propane, steam, or fuel oil and powered by electric motors. Grain dryers normally are equipped for automatic operation and will shut down in the event of overheating. Dryers move large volumes of heated air through perforated screens and the columns of gravity-fed grain.
Common Causes of Dryer Fires
A common dryer malfunction is plugging of the grain flow, which can result in smoldering grain or foreign material in the grain within the dryer. This can result in a dryer fire and/or the conveying of smoldering or hot grain to a storage bin.
Mechanical failures and the lack of an effective maintenance plan also create the potential for dryer fires. A proper maintenance plan and established fire-prevention measures can limit dryer downtime during harvest and reduce potential injury and/or property loss.
Inadequate operator training, combined with a lack of operational oversight, create other opportunities for dryer fires to occur. For example, operating dryers at excessively hot temperatures can increase the risk of fire; therefore, many dryers have automatic shut-off features in the event temperatures reach a critical level. Other significant contributors to increased dryer fire risks include the lack of timely cleaning and inspection of the manufacturer’s recommended susceptible areas.
Dryer Fire Prevention
An effective preventive maintenance program, which includes the following tips on startup, cleaning, and shutdown, can help reduce the potential for grain dryer fires.
• Have dryers inspected annually by the manufacturer or a reputable dryer service provider.
• Pressure test and inspect fuel lines.
• Inspect all grain handling equipment. Fill and discharge conveyors and distributors.
• Check operating controls for proper function.
• Check and test any installed hazard-monitoring system.
• Ensure that all emergency discharge gates are closed and there is no residual grain-related material from previous use in the distributor or columns.
• Remember to remove the tarp from the burner.
• Follow the manufacturer’s cleaning priority schedule. Some areas of the dryer are a higher priority and require more frequent cleaning than others. Typically, manufacturers recommend cleaning at least every 24 hours of operation, but every 12 hours is a best practice.
• Allow the dryer to cool before entering, and follow company/facility procedures prior to entry.
• Cover the burner with a tarp, especially if you are cleaning with water.
• Empty the dryer completely.
• Thoroughly inspect all portions of the dryer for material buildup. Clean these areas, if necessary.
• If applicable, open the drain valves on the fuel supply.
• Leave the tarp over the burner in a fashion that does not create a funnel and collect water.
• Provide a fire watch after the dryer has been shut down.
This article is one in a series of Safety Tips published by the National Grain and Feed Association (NGFA), Arlington, VA (202-289-0873). To view more NGFA Safety Tips, go to ngfa.org and click on Issues.