Fighting Fire With Prevention

Fire is a common hazard in the scrap processing industry, yet many companies do not have a fire prevention program. Here are the basics of what you need to know to guard against such a devastating loss.

Ironically, companies that have suffered a major fire loss are the most attentive to fire prevention. Such companies, having been literally burned once, become concerned, aware, and active in prevention programs. Few operations that have survived a major fire ever have a second one, in large part because of the prevention programs they establish.

With so much to lose, scrap processors can't afford not to develop a fire prevention program. Such programs have proved to be effective preventive measures that offer increased safety for the company, its property, its employees, and surrounding properties and the environment.

Assessing the Potential Damage

Fire can be contained and used for specific purposes. However, when a fire escapes containment, it can cause financial loss in several areas:

Direct damage: Fire can destroy buildings, equipment, and scrap material.

Indirect damage: The direct damage often causes a partial or total closing of operations, resulting in a loss of revenue. Scrap recyclers also might be unable to use or sell damaged or destroyed material.

Consequential loss: Employees who are injured by the fire have recourse under worker's compensation law.

If the fire was caused through the company's negligence, it may be liable for any damage to people and/or their property, either from the fire itself or toxic combustion byproducts. For example, suppose a pile of engine blocks awaiting processing is stored under a highway overpass. If the thousands of gallons of heavy oil contained in those engine blocks were to catch fire, the heat generated by that fire would be tremendous. The fire would be likely to cause major structural damage to the highway overpass, which could run to millions of dollars. If found negligent, the scrap processor would be liable for those damages.

Scrap-plant fires may also start in piles of shredder fluff, the combustion byproducts of which could create a nightmare. If the fire was caused by the processor's negligence, every home, neighboring business, or passing motorist that had contact with the smoke from that fire is a potential liability claimant.

To help prevent the damage and liability of a business-related fire, scrap processors should establish a fire prevention program that addresses the special nature of their particular operations. In general, every company's in-house prevention program should include regular inspections, a fire-spread-containment plan, and an emergency response plan. In addition, in order to best understand what might cause a fire and why, a basic education in fire science is vital. See sidebar at left.

The Importance of Regular Inspections

Companies should conduct regular inspections of their operations based on a fire prevention checklist. Keep records of all inspections, as these can be invaluable tools for monitoring trouble spots and defending against liabilities.

Develop rapport with local fire department personnel and invite them to review your operations. Ask for a copy of their report and respond to their suggestions. It is better to discover-and solve-problems when they are small.

If your insurance company inspects your operation for fire hazards, accompany the inspector on the review in hopes of learning from the inspector's expertise and offering your comments. After the inspection, try to obtain a copy of the report.

Include fire prevention in your equipment maintenance program. The value of your supplies and equipment becomes most apparent when they are damaged or out of service. While iron and steel do not readily bum, they can be. damaged, and support components, such as hydraulic and electrical systems, can be destroyed by fire. A crane that is covered with grease and oil residue should be steam cleaned Or Pressure washed. That way, if there is a small fire in the crane's engine housing, it will not have an abundance of fuel on which to spread. The damage caused by a minor fire can usually be repaired rapidly. A major fire can impair the equipment indefinitely or destroy it.

Preparing a Fire-Spread-Containment Plan

A fire can develop and spread swiftly. For example, once flaming combustion is established, fire can spread over hydrocarbon fuels, such as grease and oil residue on a crane or on scrap metal, at about 8 feet per second. It can spread across paper at nearly the same rate.

One scrap paper handler learned this the hard way. The processor had corrugated and other paper piled in a pit next to the warehouse. One of the firm's customers discarded a cigarette, which ignited the paper in the pit. Before company personnel could respond, the entire pit was in flames. Even the fire department could not prevent the fire from destroying the entire warehouse, which was constructed of "fireproof' material. While the building did not bum, its contents did, and the building lost its structural integrity.

Plant fires can become huge problems as radiant energy transferred from a fire in one area ignites fuels, such oil and grease, in other areas. It is similar to cases in which frame houses burst into flames when several thousand feet away from a forest fire.

Developing a Fire Emergency Plan

One of the greatest mistakes a business owner can make is to assume that people will think logically in an emergency. Prepare a sound plan for notifying the fire department and test employees on it. Have backup plans in case telephone lines are down. Prepare for the worst.

Another important preparation step is the possession of extinguishing equipment. Determine what areas of your facility have high fire potential and make certain that extinguishing equipment is placed near, but not in, those locations. If you place an extinguisher on a wall near fuel that could possibly catch fire, how could an employee reach the extinguisher? Place the extinguisher near that location so it can be reached quickly and safely.

Having the proper extinguishing tool for specific types of fires is vital. One company had a 2-inch water line at the pit where it stored magnesium turnings. If the turnings caught fire and water was used to suppress it, because of inherent magnesium qualities, the fire would intensify and a devastating explosion could occur. Wet-type extinguishers also don't belong in a room containing electronic equipment. Your supplier or fire department can tell you the type of extinguishing agents you need for particular fires.

Employees must be trained in the use of the company's extinguishers. Suppose a small pile of paper caught fire in the doorway of your paper warehouse. An employee grabs the extinguisher, rushes over to it, pulls the pin, and blasts the flaming paper into a huge pile of corrugated. Result: Your warehouse bums down.

Many of your employees probably have never used an extinguisher. Remember that in panic situations no one reads instructions have your supplier give a demonstration for your workers about once a year and make certain that new employees are trained in extinguisher use.

Establish evacuation procedures if your operation warrants, making certain that your employees are aware of evacuation routes. Practice evacuating your employees. We do not outgrow our need for fire drills when we leave school--we just think we do.

Also train employees in potential toxic byproduct concerns. Chemical changes take place when a fuel burns, and many scrap products can present health hazards in a fire. While employees initially may be able to fight some fires, they should avoid others. Plastics, for examples present a broad range of toxic-to-highly-toxic byproducts when burning. A fire in a pile of shredder fluff should not be approached without proper protective equipment and respirators. Additional information in this area has been compiled by the National Fire Protection Association (Quincy, Mass.).

Fire Prevention Checklist

The following checklist does not represent a comprehensive list; rather, it highlights areas that you may not have considered. Each item should be addressed in your fire prevention inspections, if applicable to your operation. Note the spectrum of the low-temperature heat effect, as items in that category are not distinguished in this list.

Buildings:

Note the fire potential in electrical boxes, conduits, and equipment.

Inspect furnaces, boilers, and water heaters.

Check the use and condition of extension cords.

Avoid storing chemicals, flammables, combustibles, and reactive materials.

Don't store liquid and solid combustibles in areas where grinding and welding take place.

Don't allow heat-producing equipment to be attached to or surrounded by combustibles (such as telephone system transformers, calculator transformers, ballasts, and light bulbs).

Inspect areas above suspended ceilings and in partition walls. The fluorescent lights above a suspended ceiling should never be fastened directly to a wood structure. The ballast produces sufficient heat to initiate pyrolysis. insulation around these lights will trap the heat and accelerate the process.

Equipment:

Be aware that oil leaks and oily coatings provide a fuel for fire.

Keep electrical covers m place and check wiring regularly for indication of damage.

Be aware of dust-explosion potential in paper shredders.

Don't store rags, boxes, and flammables in equipment.

Regularly check the integrity of LP-gas supply lines.

Note that exhaust stems are a danger, especially in paper operations.

Be aware that friction caused by worn parts creates tremendous heat.

Paper Operations:

Replace damaged extension cords, which can arc or heat.

Remove damaged or trapped electrical fixtures. Cover open junction boxes on equipment. If a wire outside the box loosened, arcing could ignite paper in close proximity.

Control nearby cigarette smoking.

Note that metal buckets, blades, and banded paper bales can create frictional heat--and sparks--when pushed along a concrete floor.

Metallic Operations:

Reduce potential fires by isolating heat-producing operations, such as torch work.

Minimize fire spread potential by placing scrap piles away from each other and other fuels.

Protect your gasoline, diesel fuel, liquid oxygen, and propane tanks from possible rupture by nearby equipment. Give them the respect they deserve.

Provide warnings and instructions at fuel tanks.

A fire prevention program is a prudent investment for every scrap business but one that requires foresight, preparation, and conscientious adherence to established rules. There is no wisdom in being "once burned, twice smart" when dealing with the protection of your business. Armed with information, scrap processors can create a prevention program to ensure the health and safety of their businesses and employees. This is one situation in which an ounce of prevention is worth any amount of cure.

[SIDEBAR]

Getting Down to Basics

                Few of the thousands of fires in this country each year are caused by obvious hazards. Everyone knows you don’t put a 50-gallon drum of gasoline next to a rotating-hearth furnace. Most fires are caused by hidden hazards that are often not addressed in prevention programs--the inadvertent storage of a chemical oxidizer with an organic compound, an extension cord lodged under a bale of paper, or a light bulb snuggled next to stored corrugated board. Therefore, the first step in any fire prevention program should be a basic education in fire science. How can you prevent what you don’t understand?

                Fire is a combustion reaction. As such, it is usually beneficial: It makes our car engines operate, cooks our food, heats our homes, and lights our workplaces. Yet few people understand how a fire “works.”

                In grade school, we learned about the fire triangle: To create a fire, you must have oxygen, fuel, and a heat source. If you remove any one of these elements, the fire will not continue. While this concept is very basic, each element has several important variables.

                Understanding Oxygen: Oxygen makes up about 20 percent of our atmosphere. But a fire will burn, albeit slowly, in air that contains 14 percent oxygen; smoldering combustion may continue at even lower oxygen levels. Higher oxygen contents will accelerate burning. In oxygen concentrations of 25 percent or more, minute combustion reactions that go on around us all the time--such as organic decay and drying paint--can accelerate into flaming combustion.

                For example, in one situation, the contents of a liquid oxygen tank were released, and the expanding vapor cloud passed through a barn a quarter mile away. The barn burst into flames because the curing process of the hay inside (a slow combustion reaction) accelerated into a flame reaction.

                Fuel Facts: Fuels can be classified into three types--solids, liquids, and gases. Most fuels burn in the gaseous state, which makes fuel gases particularly dangerous. They are always in the proper state to burn, regardless of ignition temperature--the point at which a fuel will ignite and burn--or burning rate. For example, although the ignition temperature of hydraulic oil is slightly lower than the ignition temperature of LP gas, the LP gas presents the greater fire hazard. A gas, when it reaches its ignition temperature, will ignite instantly because it does not have to go through any chemical conversion to become a gas.

                Liquid fuels, on the other hand, do. Liquids are classified as either flammable or combustible. Gasoline is a common flammable fuel, while diesel is a common combustible fuel. The ignition temperature is very close for gas an diesel. Each will burn with similar intensity. So why the difference?

                It is due solely to the temperature at which the liquids will produce flammable vapors. Diesel fuel will not convert naturally to a gas until about 110 to 130 degrees F. Gasoline, however, produces flammable vapors at -54 degrees F. Since it is the gas, not the liquid, that burns, gasoline is obviously a greater fire hazard than diesel fuel.

                Solid fuels also must undergo a chemical conversion--known as pyrolysis--to a gas before they can burn. This change can occur quickly or slowly and, again, does not rely on ignition temperature. Butane gas ignites at about 800 degrees F, while a sliver of pine wood ignites at about 500 degrees F. The spark from the flint of a butane lighter has a temperature of about 1,000 degrees F--enough to easily ignite the butane gas. Yet it will not cause the pine to burn, even though the pine has an ignition temperature that’s half the spark’s temperature. This is because the heat duration is not long enough to cause the wood to undergo the chemical change necessary to liberate its flammable gases.

                The insulation on an electrical conductor contains hydrogen and carbon atoms. The balance of its chemical content makes it an insulator, a nonconductor of electricity. However, when exposed to sufficient heat over sufficient time, the lighter hydrogen atoms will dissipate and the heavier carbon atoms--which conduct electricity--will remain. While the insulation may look the same, its chemical makeup has changed dangerously.

                Chemical changes in solid fuels can occur quickly. Set the end of a piece of paper on fire, then extinguish it. The resulting material will include transitional areas that begin at the undamaged paper, then turn yellow-brown, then brown, and, finally, black (ash). The yellow-brown area is the pyrolysis zone, where the paper was rapidly going through this chemical change.

                This process can also occur slowly, over a period of days, weeks, months, or even years. Pyrolysis can potentially occur at temperatures as low as 150 degrees F. This low-temperature heat effect causes thousands of fires each year because people do not recognize such low temperatures as a potential fire hazard.

                For instance, a 100-watt light bulb caused the $2-million fire at Chicago’s Marshall Fields Annex following a heat exposure lasting about 26 hours. The $32-million fire at McCormick Place in Chicago was caused after 72 hours of use of an overheated power cord. And it was a hot-water line--and a heat duration of three or four days--that burned and severely damaged a new railroad crane owned by a Wisconsin scrap processor.

                None of these heat sources exceeded 200 degrees F. However, the chemical change in fuels caused by even relatively low temperatures can result in a drop in the fuel’s ignition temperature. If the ignition temperature falls to the level of the heat being applied, a fire will occur. Thus, any heat source is potentially dangerous.

                Heat Formulas: These ideas of how fire relates to time and temperature can be expressed in terms of the following equations:

                Time + temperature = fire.

                If combustible solid fuel is handled at temperatures above 150 degrees F, the low-temperature heat effect will occur. At low temperatures the formula changes:

                Less temperature + more time = fire.

                As the temperature increases, the time necessary to cause fire decreases. For example, when an electrical short circuit occurs, the temperature curve of the arc may exceed 5,000 degrees F. Although the heat duration may be short, it can ignite many fuels if they are close enough. At high temperatures the formula changes again:

                More temperature + less time = explosion.

                In its simplest form, an explosion is a very fast moving fire that is burning fuel suspended or mixed in the air. Scrap processors deal with two types of fuel that, if ignited, will trigger an explosion: gas--such as LP, acetylene, or natural gas--and solids--including metallic dust and paper.

Fire is a common hazard in the scrap processing industry, yet many companies do not have a fire prevention program. Here are the basics of what you need to know to guard against such a devastating loss.

Ironically, companies that have suffered a major fire loss are the most attentive to fire prevention. Such companies, having been literally burned once, become concerned, aware, and active in prevention programs. Few operations that have survived a major fire ever have a second one, in large part because of the prevention programs they establish.

With so much to lose, scrap processors can't afford not to develop a fire prevention program. Such programs have proved to be effective preventive measures that offer increased safety for the company, its property, its employees, and surrounding properties and the environment.

Assessing the Potential Damage

Fire can be contained and used for specific purposes. However, when a fire escapes containment, it can cause financial loss in several areas:

Direct damage: Fire can destroy buildings, equipment, and scrap material.

Indirect damage: The direct damage often causes a partial or total closing of operations, resulting in a loss of revenue. Scrap recyclers also might be unable to use or sell damaged or destroyed material.

Consequential loss: Employees who are injured by the fire have recourse under worker's compensation law.

If the fire was caused through the company's negligence, it may be liable for any damage to people and/or their property, either from the fire itself or toxic combustion byproducts. For example, suppose a pile of engine blocks awaiting processing is stored under a highway overpass. If the thousands of gallons of heavy oil contained in those engine blocks were to catch fire, the heat generated by that fire would be tremendous. The fire would be likely to cause major structural damage to the highway overpass, which could run to millions of dollars. If found negligent, the scrap processor would be liable for those damages.

Scrap-plant fires may also start in piles of shredder fluff, the combustion byproducts of which could create a nightmare. If the fire was caused by the processor's negligence, every home, neighboring business, or passing motorist that had contact with the smoke from that fire is a potential liability claimant.

To help prevent the damage and liability of a business-related fire, scrap processors should establish a fire prevention program that addresses the special nature of their particular operations. In general, every company's in-house prevention program should include regular inspections, a fire-spread-containment plan, and an emergency response plan. In addition, in order to best understand what might cause a fire and why, a basic education in fire science is vital. See sidebar at left.

The Importance of Regular Inspections

Companies should conduct regular inspections of their operations based on a fire prevention checklist. Keep records of all inspections, as these can be invaluable tools for monitoring trouble spots and defending against liabilities.

Develop rapport with local fire department personnel and invite them to review your operations. Ask for a copy of their report and respond to their suggestions. It is better to discover-and solve-problems when they are small.

If your insurance company inspects your operation for fire hazards, accompany the inspector on the review in hopes of learning from the inspector's expertise and offering your comments. After the inspection, try to obtain a copy of the report.

Include fire prevention in your equipment maintenance program. The value of your supplies and equipment becomes most apparent when they are damaged or out of service. While iron and steel do not readily bum, they can be. damaged, and support components, such as hydraulic and electrical systems, can be destroyed by fire. A crane that is covered with grease and oil residue should be steam cleaned Or Pressure washed. That way, if there is a small fire in the crane's engine housing, it will not have an abundance of fuel on which to spread. The damage caused by a minor fire can usually be repaired rapidly. A major fire can impair the equipment indefinitely or destroy it.

Preparing a Fire-Spread-Containment Plan

A fire can develop and spread swiftly. For example, once flaming combustion is established, fire can spread over hydrocarbon fuels, such as grease and oil residue on a crane or on scrap metal, at about 8 feet per second. It can spread across paper at nearly the same rate.

One scrap paper handler learned this the hard way. The processor had corrugated and other paper piled in a pit next to the warehouse. One of the firm's customers discarded a cigarette, which ignited the paper in the pit. Before company personnel could respond, the entire pit was in flames. Even the fire department could not prevent the fire from destroying the entire warehouse, which was constructed of "fireproof' material. While the building did not bum, its contents did, and the building lost its structural integrity.

Plant fires can become huge problems as radiant energy transferred from a fire in one area ignites fuels, such oil and grease, in other areas. It is similar to cases in which frame houses burst into flames when several thousand feet away from a forest fire.

Developing a Fire Emergency Plan

One of the greatest mistakes a business owner can make is to assume that people will think logically in an emergency. Prepare a sound plan for notifying the fire department and test employees on it. Have backup plans in case telephone lines are down. Prepare for the worst.

Another important preparation step is the possession of extinguishing equipment. Determine what areas of your facility have high fire potential and make certain that extinguishing equipment is placed near, but not in, those locations. If you place an extinguisher on a wall near fuel that could possibly catch fire, how could an employee reach the extinguisher? Place the extinguisher near that location so it can be reached quickly and safely.

Having the proper extinguishing tool for specific types of fires is vital. One company had a 2-inch water line at the pit where it stored magnesium turnings. If the turnings caught fire and water was used to suppress it, because of inherent magnesium qualities, the fire would intensify and a devastating explosion could occur. Wet-type extinguishers also don't belong in a room containing electronic equipment. Your supplier or fire department can tell you the type of extinguishing agents you need for particular fires.

Employees must be trained in the use of the company's extinguishers. Suppose a small pile of paper caught fire in the doorway of your paper warehouse. An employee grabs the extinguisher, rushes over to it, pulls the pin, and blasts the flaming paper into a huge pile of corrugated. Result: Your warehouse bums down.

Many of your employees probably have never used an extinguisher. Remember that in panic situations no one reads instructions have your supplier give a demonstration for your workers about once a year and make certain that new employees are trained in extinguisher use.

Establish evacuation procedures if your operation warrants, making certain that your employees are aware of evacuation routes. Practice evacuating your employees. We do not outgrow our need for fire drills when we leave school--we just think we do.

Also train employees in potential toxic byproduct concerns. Chemical changes take place when a fuel burns, and many scrap products can present health hazards in a fire. While employees initially may be able to fight some fires, they should avoid others. Plastics, for examples present a broad range of toxic-to-highly-toxic byproducts when burning. A fire in a pile of shredder fluff should not be approached without proper protective equipment and respirators. Additional information in this area has been compiled by the National Fire Protection Association (Quincy, Mass.).

Fire Prevention Checklist

The following checklist does not represent a comprehensive list; rather, it highlights areas that you may not have considered. Each item should be addressed in your fire prevention inspections, if applicable to your operation. Note the spectrum of the low-temperature heat effect, as items in that category are not distinguished in this list.

Buildings:

Note the fire potential in electrical boxes, conduits, and equipment.

Inspect furnaces, boilers, and water heaters.

Check the use and condition of extension cords.

Avoid storing chemicals, flammables, combustibles, and reactive materials.

Don't store liquid and solid combustibles in areas where grinding and welding take place.

Don't allow heat-producing equipment to be attached to or surrounded by combustibles (such as telephone system transformers, calculator transformers, ballasts, and light bulbs).

Inspect areas above suspended ceilings and in partition walls. The fluorescent lights above a suspended ceiling should never be fastened directly to a wood structure. The ballast produces sufficient heat to initiate pyrolysis. insulation around these lights will trap the heat and accelerate the process.

Equipment:

Be aware that oil leaks and oily coatings provide a fuel for fire.

Keep electrical covers m place and check wiring regularly for indication of damage.

Be aware of dust-explosion potential in paper shredders.

Don't store rags, boxes, and flammables in equipment.

Regularly check the integrity of LP-gas supply lines.

Note that exhaust stems are a danger, especially in paper operations.

Be aware that friction caused by worn parts creates tremendous heat.

Paper Operations:

Replace damaged extension cords, which can arc or heat.

Remove damaged or trapped electrical fixtures. Cover open junction boxes on equipment. If a wire outside the box loosened, arcing could ignite paper in close proximity.

Control nearby cigarette smoking.

Note that metal buckets, blades, and banded paper bales can create frictional heat--and sparks--when pushed along a concrete floor.

Metallic Operations:

Reduce potential fires by isolating heat-producing operations, such as torch work.

Minimize fire spread potential by placing scrap piles away from each other and other fuels.

Protect your gasoline, diesel fuel, liquid oxygen, and propane tanks from possible rupture by nearby equipment. Give them the respect they deserve.

Provide warnings and instructions at fuel tanks.

A fire prevention program is a prudent investment for every scrap business but one that requires foresight, preparation, and conscientious adherence to established rules. There is no wisdom in being "once burned, twice smart" when dealing with the protection of your business. Armed with information, scrap processors can create a prevention program to ensure the health and safety of their businesses and employees. This is one situation in which an ounce of prevention is worth any amount of cure.

[SIDEBAR]

Getting Down to Basics

                Few of the thousands of fires in this country each year are caused by obvious hazards. Everyone knows you don’t put a 50-gallon drum of gasoline next to a rotating-hearth furnace. Most fires are caused by hidden hazards that are often not addressed in prevention programs--the inadvertent storage of a chemical oxidizer with an organic compound, an extension cord lodged under a bale of paper, or a light bulb snuggled next to stored corrugated board. Therefore, the first step in any fire prevention program should be a basic education in fire science. How can you prevent what you don’t understand?

                Fire is a combustion reaction. As such, it is usually beneficial: It makes our car engines operate, cooks our food, heats our homes, and lights our workplaces. Yet few people understand how a fire “works.”

                In grade school, we learned about the fire triangle: To create a fire, you must have oxygen, fuel, and a heat source. If you remove any one of these elements, the fire will not continue. While this concept is very basic, each element has several important variables.

                Understanding Oxygen: Oxygen makes up about 20 percent of our atmosphere. But a fire will burn, albeit slowly, in air that contains 14 percent oxygen; smoldering combustion may continue at even lower oxygen levels. Higher oxygen contents will accelerate burning. In oxygen concentrations of 25 percent or more, minute combustion reactions that go on around us all the time--such as organic decay and drying paint--can accelerate into flaming combustion.

                For example, in one situation, the contents of a liquid oxygen tank were released, and the expanding vapor cloud passed through a barn a quarter mile away. The barn burst into flames because the curing process of the hay inside (a slow combustion reaction) accelerated into a flame reaction.

                Fuel Facts: Fuels can be classified into three types--solids, liquids, and gases. Most fuels burn in the gaseous state, which makes fuel gases particularly dangerous. They are always in the proper state to burn, regardless of ignition temperature--the point at which a fuel will ignite and burn--or burning rate. For example, although the ignition temperature of hydraulic oil is slightly lower than the ignition temperature of LP gas, the LP gas presents the greater fire hazard. A gas, when it reaches its ignition temperature, will ignite instantly because it does not have to go through any chemical conversion to become a gas.

                Liquid fuels, on the other hand, do. Liquids are classified as either flammable or combustible. Gasoline is a common flammable fuel, while diesel is a common combustible fuel. The ignition temperature is very close for gas an diesel. Each will burn with similar intensity. So why the difference?

                It is due solely to the temperature at which the liquids will produce flammable vapors. Diesel fuel will not convert naturally to a gas until about 110 to 130 degrees F. Gasoline, however, produces flammable vapors at -54 degrees F. Since it is the gas, not the liquid, that burns, gasoline is obviously a greater fire hazard than diesel fuel.

                Solid fuels also must undergo a chemical conversion--known as pyrolysis--to a gas before they can burn. This change can occur quickly or slowly and, again, does not rely on ignition temperature. Butane gas ignites at about 800 degrees F, while a sliver of pine wood ignites at about 500 degrees F. The spark from the flint of a butane lighter has a temperature of about 1,000 degrees F--enough to easily ignite the butane gas. Yet it will not cause the pine to burn, even though the pine has an ignition temperature that’s half the spark’s temperature. This is because the heat duration is not long enough to cause the wood to undergo the chemical change necessary to liberate its flammable gases.

                The insulation on an electrical conductor contains hydrogen and carbon atoms. The balance of its chemical content makes it an insulator, a nonconductor of electricity. However, when exposed to sufficient heat over sufficient time, the lighter hydrogen atoms will dissipate and the heavier carbon atoms--which conduct electricity--will remain. While the insulation may look the same, its chemical makeup has changed dangerously.

                Chemical changes in solid fuels can occur quickly. Set the end of a piece of paper on fire, then extinguish it. The resulting material will include transitional areas that begin at the undamaged paper, then turn yellow-brown, then brown, and, finally, black (ash). The yellow-brown area is the pyrolysis zone, where the paper was rapidly going through this chemical change.

                This process can also occur slowly, over a period of days, weeks, months, or even years. Pyrolysis can potentially occur at temperatures as low as 150 degrees F. This low-temperature heat effect causes thousands of fires each year because people do not recognize such low temperatures as a potential fire hazard.

                For instance, a 100-watt light bulb caused the $2-million fire at Chicago’s Marshall Fields Annex following a heat exposure lasting about 26 hours. The $32-million fire at McCormick Place in Chicago was caused after 72 hours of use of an overheated power cord. And it was a hot-water line--and a heat duration of three or four days--that burned and severely damaged a new railroad crane owned by a Wisconsin scrap processor.

                None of these heat sources exceeded 200 degrees F. However, the chemical change in fuels caused by even relatively low temperatures can result in a drop in the fuel’s ignition temperature. If the ignition temperature falls to the level of the heat being applied, a fire will occur. Thus, any heat source is potentially dangerous.

                Heat Formulas: These ideas of how fire relates to time and temperature can be expressed in terms of the following equations:

                Time + temperature = fire.

                If combustible solid fuel is handled at temperatures above 150 degrees F, the low-temperature heat effect will occur. At low temperatures the formula changes:

                Less temperature + more time = fire.

                As the temperature increases, the time necessary to cause fire decreases. For example, when an electrical short circuit occurs, the temperature curve of the arc may exceed 5,000 degrees F. Although the heat duration may be short, it can ignite many fuels if they are close enough. At high temperatures the formula changes again:

                More temperature + less time = explosion.

                In its simplest form, an explosion is a very fast moving fire that is burning fuel suspended or mixed in the air. Scrap processors deal with two types of fuel that, if ignited, will trigger an explosion: gas--such as LP, acetylene, or natural gas--and solids--including metallic dust and paper.