Canadian Consulting Engineer

down on the farm

May 1, 2001
By David Torvi, Ph.D., P.Eng

Agricultural buildings across Canada range from farm buildings to grain elevators to animal barns to food processing facilities. Although a relatively small percentage of fires in Canada occur in thes...

Agricultural buildings across Canada range from farm buildings to grain elevators to animal barns to food processing facilities. Although a relatively small percentage of fires in Canada occur in these buildings, the economic losses that result when such tragedies happen can be substantial.

In 1996, for example, 941 fires occurred in farm buildings in Canada, which was 1.6% of the total number of fires reported.1 In terms of financial cost, however, these fires amounted to a loss of $56 million, almost 5% of the total fire losses in Canada. There were 15 fires in farm facilities, agricultural supply storage buildings, or meat or poultry preparation facilities where losses were greater than $500,000. In six of these fires, the losses were greater than $1 million.

As agricultural buildings typically contain very small numbers of people, the number of human injuries and deaths are relatively small: 25 injuries (0.8% of the total) in 1996, and two deaths (0.6% of the total). However, the number of animals that die can be very large. A fire in a hog barn earlier this year in Saskatchewan, for example, killed 14,000 animals, and resulted in millions of dollars in estimated damages.

Agricultural facilities present unique challenges for fire prevention and suppression. They are often in remote locations and not continually monitored. Also, their fuel loads can differ from those in offices, homes and most industrial facilities. Special challenges include:

characteristics of materials within agricultural buildings

characteristics of agricultural buildings

times required for detection

location of buildings

evacuation of animals during a fire

economic impact of fire on smaller communities.

This article discusses these challenges, along with ways in which industry, the fire service, and researchers are responding to them.

Dangers and detection

Some materials and substances used in agricultural buildings burn rapidly if ignited. Chemicals (used in fertilizers and pesticides, for example) might be stored in the building, and there can be unprotected insulating material in the walls of the structure itself. The rapid growth of fire has an impact on the ability of the fire department to extinguish the fire, the time it takes for structural members and walls to fail, and the safety of humans and animals.

Strategies to prevent the rapid spread of fire used by those who design buildings for the agriculture industry are similar to those used in other industries. They include designing fire stops between ceilings and roofs, specifying minimum fire resistance and flame spread ratings in certain occupancies, treating wood with fire retardants, protecting metal frames, and separating buildings to avoid the spread of fire. Besides these methods of reducing the effects of fire, public education campaigns emphasize prevention. They stress aspects such as the importance of housekeeping and the frequent inspection of electrical systems.

Agricultural facilities also contain hazardous materials. Examples are pesticides and some natural plants that give off toxic gases when burned.2 Hazardous materials are, of course, dangerous to firefighters and animals, and can contaminate run-off from the water used by firefighters. It is important, therefore, that fire departments are aware what particular materials are stored in the facilities they may respond to, so that they can take appropriate precautions in a fire.

Materials in agricultural facilities also carry a risk of spontaneous ignition. This danger has resulted in recommendations for the processing and storage of products such as vegetable and animal oils, wool, flax, hay and milk powder. Hay, for example, should be cured to the proper moisture content in order to avoid its ignition due to heating by microbiological and other thermal chemical processes.

Agricultural buildings are often quite different from other buildings. Many, for example, have high ceilings, which can affect fire detection times. It will take a relatively long time for the temperature or smoke concentration at the ceiling to be high enough to activate detectors. Building compartment sizes may be very large, which affects the spread of fire. If buildings are dusty, this too can affect the operation of detectors.

As many of these buildings are not continually occupied, it is not as likely that someone will discover the fire as in a building such as an office where large numbers of people are present for most of the day. When reading accounts of many fires in agricultural facilities, one often hears that they were not discovered until a passer-by noticed that the building was almost completely on fire. Detection is one area where further research is needed to develop cost-effective fire protection strategies.

Other features of farm buildings, such as the large doors that are necessary for the movement of machinery and livestock inside and out, have an impact on fire spread and detection. These doors can make a large amount of oxygen available to support a fire. Also, air movement through the doors can affect the movement of hot gases above a fire, which in turn may affect the efficiency of fire detectors.

Just as building codes specify minimum spatial separations in urban areas, codes also specify minimum distances between agricultural buildings in order to prevent the spread of fire. An important point to realize when determining such distances is that many building codes base their requirements on heat fluxes measured in experiments conducted by the National Research Council of Canada in the late 1950s. During these experiments, it was found that the heat values increased after 16 minutes.3 As the lower heat flux values were used in building codes to develop the spatial separation guidelines, it may be appropriate to increase the distances between buildings beyond the code requirements when you expect that fire departments may take a long time to respond to a fire.

Getting the horse out of the barn

The remote location of many agricultural facilities can cause a relatively long delay before the fire department arrives and begins to suppress the fire. In addition, there may not be enough water to fight the blaze because the water supply infrastructure is not available. Therefore, design guides and standards, such as NFPA 1142, specify the amount of water that should be readily available for firefighters where there are no fire hydrant systems.

Firefighters may be less familiar with agricultural buildings than the types of buildings they typically respond to.4 Access for fire trucks may be limited. As well, equipment for extricating people from automobiles is not designed for agricultural equipment, so it may be difficult to rescue people trapped inside farm machinery.

Since large numbers of animals may be in the building, and confined spaces may be oxygen-deficient, pre-planning is very important for building designers and fire service personnel.

Generally, animals cannot evacuate by themselves as they will be in cages, pens or stalls. They will also need to be guided out of the building should a fire occur, and to be taken to a safe area outside the facility. One example of how these concerns are addressed is the development of escape plans for horse barns.5 Plans include identifying escape routes for each stall in the barn, and marking these routes with exit signs and lines on the floor. Plans also include a safe place of refuge, which is large enough to accommodate all the animals in the barn. Proper equipment for leading the horses out of the barn must also be placed in an easily accessible location.

It is important to provide training for firefighters, who may not be used to handling horses, as well as for horses, who otherwise would not be used to smoke and firefighters. Regular fire drills are important. Some barns have even included the use of simulated smoke in fire drills, in order to help horses get used to conditions they may encounter in an actual fire, and to give firefighters experience in handling horses under these conditions.

As mentioned earlier,
although the number of human casualties may be small in agriculture building fires, the number of animals that die can be very large. Facilities may be extensive and contain a great deal of equipment, so economic losses can be substantial. And as many agricultural facilities are located in smaller communities, the effect of a fire on a major employer or a family farm can be devastating. Even if there are only partial losses, damage to key equipment or facilities can make operations difficult, especially if fire occurs during harvest or another busy part of the year.

With plans afoot to increase the size of agricultural operations even further in Canada and elsewhere, it will become important to supplement existing fire protection strategies and technologies with other cost-effective systems. These might be systems that are used in other buildings, or are developed specifically for agricultural buildings. Advanced fire modelling and testing should be used to study fires in agricultural buildings in order to help develop guidelines and fire protection systems that will increase safety for both humans and animals, as well as reduce fire losses. Research at the University of Saskatchewan and other institutions in Canada and around the world is continuing in order to meet these goals.

A number of resources are available in print and/or on the World Wide Web, which provide information to the agricultural industry on fire behaviour, fire prevention, suppression, and other fire safety topics. One example of online resources is the National Agricultural Safety Database, Other good sources of information are engineering colleges and extension divisions of schools such as the University of Minnesota, Oklahoma State University, North Dakota State University and Purdue University, which have agricultural safety departments or divisions.

Dr. David Torvi, Ph.D., P.Eng. is an assistant professor in the Department of Mechanical Engineering at the University of Saskatchewan.

1 1996 Annual Report of Fire Losses in Canada, Council of Canadian Fire Marshals and Fire Commissioners.

2 Nelson, G.L., “Fire and Pesticides, a Review and Analysis of Recent Work,” Fire Technology, Vol. 36, 2000, pp. 163-183.

3 McGuire, J.H., “Fire and the Spatial Separation of Buildings,” Fire Technology, Vol. 1, 1965, pp. 278-287.

4 Minor, G.L., “Agricultural Rescue: Hidden Dangers for Responders,” Firehouse, Vol. 25, October 2000, pp. 92-93.

5 Hicks, F.L., Jr., “Developing an Equine Barn Escape Plan,” Firehouse, Vol. 18, March 1993, pp. 32-34.


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