This article is based on a presentation, “Grain Dryer Service for Fire Prevention,” by Allan Schmidt, senior service technician, Ag Dryer Services, Inc., Elm Creek, NE (800-657-2184).
Schmidt spoke July 29 as part of CONVEY ‘20, a virtual operations workshop held online by the National Grain and Feed Association (NGFA), the Grain Elevator and Processing Society (GEAPS), and Grain Journal.
Where do fires most often occur in a grain dryer?
Most grain dryer fires occur when a section of the dryer, which is fueled by natural gas or propane, becomes plugged and the grain and related material overheats.
For this reason, dryers usually are equipped with an automatic shutoff feature to prevent overheating.
Dryers may also be equipped with a separate power source for the discharge rolls and emergency dump system so that the power for these systems will not be lost if main dryer power is disconnected, but separate power sources are very uncommon.
Also, upper areas of dryers frequently have minimal clearance and often are difficult to reach for cleaning.
In general, can employees contain these fires relatively safely, or should the fire department be called?
Most grain dryer fires are operational in nature and can be extinguished routinely by elevator personnel by following proper operating procedures as directed by the manufacturer.
However, severe dryer fires require the assistance of professional firefighters.
In a dryer fire, be alert to the potential spread of the fire into the elevator.
The Emergency Response and Firefighting Manual published by the NGFA is an excellent reference for responding to a dryer fire (contact the NGFA at 202-289-0873 to order a copy).
What actions should employees take when a grain dryer fire is detected?
If you encounter a dryer fire, you need to shut the fuel off to the burners and shut down the power to the dryer and all associated equipment.
You then must shut down the flow of grain coming into the dryer and discontinue the flow into the facility.
If only a smoldering condition is present, or the fire is small, you may be able to scoop up the smoldering material from the floor or ledges and remove it from the dryer.
In that case, a small bucket or jug of water can be enough to extinguish the fire.
What should be done if the burning material cannot be removed manually?
If manual removal isn’t possible, activate the emergency dump and, if so equipped, the water deluge system.
According to the National Fire Protection Association (NFPA Chapter 188.8.131.52): “In the case of fires, dryers shall be designed with means for unloading (emergency dumping) of the dryer contents to a safe outside location in which the location and the manner does not cause fire exposure to adjacent buildings, structures, or equipment.”
You can also run the grain out on the discharge rolls and extinguish smoldering material by gently applying water through hose lines.
It should be noted that with soybeans the better option may be to get the grain out of the dryer fast.
A water deluge system can swell the beans so quickly that the dryer could sustain structural damage, even in places where no fire was detected.
If a fire occurred in a column of a tower dryer, is there a concern that when the column is emptied that the air space created could cause a larger fire to erupt?
It’s possible, perhaps, if the fire was also burning in a different area.
But generally, if you can determine what areas those fires are in, and you can do it quickly, this isn’t a problem.
Do I need to empty all of the grain onto the ground?
Not necessarily, if you can determine what particular area or areas of the dryer that the fire is in.
If you can’t determine the precise area of the fire in the dryer, it’s better to dump out all of the grain and not worry about the fire being carried into the elevator or elevator leg.
There could be instances when grain removal isn’t possible. What can be done from the outside?
If the burning grain cannot be removed from the dryer, use hose streams on the dryer’s exterior or gently apply water through screens, panels or holes cut in the sheet metal.
Be careful not to impair the structure’s stability, if cutting holes is necessary.
Could enough grain be fed into the dryer quickly enough to overwhelm and smother the fire?
The Occupational Safety and Health Administration (OSHA) has strict regulations for grain handling facilities that forbid attempting to smother a dryer fire in this manner.
The standard for continuous-flow bulk raw grain dryers (29 CFR 1910.272(p)) states operators will “stop the grain from being fed into the dryer if excessive temperature occurs in the exhaust of the drying section.”
Feeding grain back into the dryer in an attempt to smother the flame is a bad idea that doesn’t work, and it’s against OSHA rules.
Short answer: Don’t do it.
Can the fan be run to blow out the flame or cool down the dryer?
No, because you’re introducing more oxygen to the fire.
This is why the safety controls that have a temperature system will not allow the fan to be run.
However, a fire could be in the dryer where a temperature system may not read it, and the fans could be running.
This is where an observant dryer operator is crucial, to be sure the fans are stopped and safety measures are taken before a fire can spread.
Once a dryer fire has been extinguished, what is the next step?
After the fire is extinguished, thoroughly empty and clean the dryer so hot grain is not conveyed into the elevator.
Be sure to check all affected areas of the facility, too, for hot material that initially may have gone unnoticed, including receiving bins, conveyors, etc.
With all of the temperature and safety controls on new dryers, how is it that can fires still occur?
Simply put, we’re working with a combustible commodity and an open flame.
The observant operator has to make sure that all of the columns, all of the areas of the dryer, are metering out.
The operator must properly maintain that flow, because the safety controls are going to shut the dryer off only if it gets out of the range of the heat sensor. At that point, you already have a problem.
The heat sensor can’t keep the grain flow and the air flow correct to prevent a fire. That’s got to be done by an observant operator who also maintains and cleans the dryer.
Operators must be aware of how their particular dryer system functions, which is more than just knowing what buttons to push to get it started or stopped.
The observant operator must use all their senses, including sight, smell, and touch, to determine if the dryer system is operating properly and make adjustments as needed to prevent fires.
Grain Dryer Checklist
Courtesy of Ag Dryer Services
- From the November/December 2020 GRAIN JOURNAL