The History of Fire Fighting
Fire Fighting, techniques and equipment used to extinguish fires and limit the damage caused by them. Fire fighting consists of removing one or more of the three elements essential to combustion-fuel, heat, and oxygen-or of interrupting the combustion chain reaction.
The Roman emperor Augustus is credited with instituting a corps of fire-fighting vigiles ("watchmen") in 24 BC. Regulations for checking and preventing fires were developed. In the preindustrial era most cities had watchmen who sounded an alarm at signs of fire. The principal piece of fire-fighting equipment in ancient Rome and into early modern times was the bucket, passed from hand to hand to deliver water to the fire.
Another important fire-fighting tool was the ax, used to remove the fuel and prevent the spread of fire as well as to make openings that would allow heat and smoke to escape a burning building. In major conflagrations long hooks with ropes were used to pull down buildings in the path of an approaching fire to create firebreaks. When explosives were available, they would be used for this same purpose.
Following the Great Fire of London in 1666, fire brigades were formed by insurance companies. The government was not involved until 1865, when these brigades became London's Metropolitan Fire Brigade. The first modern standards for the operation of a fire department were not established until 1830, in Edinburgh, Scotland. These standards explained, for the first time, what was expected of a good fire department. After a major fire in Boston in 1631, the first fire regulation in America was established. In 1648 in New Amsterdam (now New York) fire wardens were appointed, thereby establishing the beginnings of the first public fire department in North America.
Fire Departments in the United States
In the modern sense, fire departments constitute a comparatively recent development. Their personnel are either volunteer (nonsalaried) or career (salaried). Typically, volunteer fire fighters are found mainly in smaller communities, career fire fighters in cities. The modern department with salaried personnel and standardized equipment became an integral part of municipal administration only late in the 19th century.
In some cities a fire commissioner administers the department; other cities have a board of fire commissioners with a fire chief as executive officer and head of the uniformed force; in still other cities a safety director may be in charge of both police and fire departments. The basic operating unit of the fire department is the company, commanded by a captain. A captain may be on duty on each shift, although in some fire departments lieutenants and sergeants command companies when the captain is off duty. Fire companies are usually organized by types of apparatus: engine companies, ladder companies, and squad or rescue companies.
Fire-alarm systems came into existence with the invention of the telegraph. Today many communities are served either with the telegraph-alarm system or with telephone call boxes. Most fires, however, are reported from private telephones. Many large cities have removed all or many of their street alarm boxes because of problems associated with maintenance and with false alarm transmissions. Some boxes have been replaced with telephones.All alarms are then transmitted to the fire stations. In large cities, alarms are received at a central dispatch office and then transmitted to fire stations, frequently with the use of mobile teleprinters and computers. Apparatus is dispatched according to the nature of the alarm and location of the fire. Many modern departments are now equipped with computer-aided dispatch systems that can track the status of all units and provide vital information about the buildings where fires occur.
Typically, on a first alarm, more apparatus is sent to industrial sections, schools, institutions, and theaters than to neighborhoods of one-family dwellings. Additional personnel, volunteer or off duty, is called as needed. Fires that cannot be brought under control by the apparatus responding to the first alarm are called multiple-alarm fires, with each additional alarm bringing more fire fighters and apparatus to the scene. Special calls are sent for specific types of equipment. Mutual aid and regional mobilization plans are in effect among adjacent fire departments for assisting each other in fighting fires.
Perhaps more important than fire fighting itself in many modern industrial countries is fire prevention. In Russia and Japan, for example, fire prevention is treated as a responsibility of citizenship. Fire fighters in the U.S. are trained in basic fire-prevention methods, and fire companies are assigned inspection districts in which they attempt to prevent or correct unsafe conditions. Fire departments are charged with enforcement of the local fire-prevention code and of state fire laws and regulations. A fire-prevention bureau in the fire department usually directs fire prevention activities. It handles the more technical fire-prevention problems, maintains appropriate records, grants licenses and permits, investigates the causes of fires, and conducts public education programs. All commercial or multiple-dwelling buildings are inspected at regular intervals, and orders are issued for the correction of violations of fire laws. If necessary, court action is taken to compel compliance.
In some communities protected by volunteer or part-time paid fire departments, fire prevention is the responsibility of a state or county fire marshal or of a professional fire staff in an otherwise voluntary organization. In addition, fire departments usually inspect commercial buildings for what is called prefire planning.
Private dwellings may also be inspected as part of a fire department's educational program to impress the importance of fire safety on the inhabitants and to check for any unsafe conditions.
Many modern fire departments spend a decreasing amount of overall activity in fighting fires. Instead, fire fighters typically respond to all kinds of emergencies. For example, in the U.S. approximately 70 percent of all emergency medical calls are handled by the fire service. The same is true in many other countries.
The enormous increase in transportation of hazardous materials or dangerous goods has resulted in intensified training for fire fighters, and their departments often provide them with chemical protective clothing and monitoring equipment. Fire departments also prepare and equip their members to handle emergencies that result from earthquakes, plane crashes, and violent storms. In addition, fire fighters handle incidents that require extricating trapped people from fallen structures, from cave-ins, and from other situations.
Fire Departments Outside the United States
Although fire fighting is largely a matter of local jurisdiction in the U.S., many countries have more centralized fire departments. Italy has a national fire service (Corpo Nazionale-Vigili del Fuoco) organized into 92 provinces, administered from 12 regional centers. In Great Britain, local fire departments are organized into county, borough, and special district departments, all under a chief inspector of fire services. In France, fire protection is administered in sectors, except in Paris, where the fire department is operated by the Sapeurs-Pompiers, a brigade of the French army, and in Marseille, where it is administered by the navy. The Japanese government administers 43 regional and 3 metropolitan fire departments. In Denmark, local governments contract for fire-fighting services with companies under supervision of the Ministry of Justice. In Germany, professional fire brigades operate in large cities; volunteer brigades serve the small towns.
In all industrial countries fire fighters undergo training, beginning with probationary fire fighters' school and continuing throughout a fire fighter's career. Great Britain has several fire training centers. In Russia, fire schools are in Moscow and Saint Petersburg; Sweden and Denmark have similar schools. In some European countries fire protection and fire fighting are among the courses included in teaching safety engineering. International fire service and fire protection associations bring together leaders of the fire services of many nations. In Europe ComitŽ Technique International de Prevention et d'Extinction du Feu (CTIF) has over 30 member nations, including Russia. The Organizaci—n Iberoamericana de Protecci—n Contra Incendios (OPCI) brings together the fire service leaders of all Latin American countries. The Asia-Pacific region is served by the Asian Pacific Fire Safety Association (APAC).
Fighting the Fire
Most fire fighting consists of applying water to the burning material, cooling it to the point at which combustion is no longer self-sustaining. Fires involving flammable liquids, certain chemicals, and combustible metals often require special extinguishing agents and techniques. With some fuels the use of water may actually be dangerous.
The first fire engines, which appeared in the 17th century, were simply tubs carried on runners, long poles, or wheels; water was still supplied to the fire site by bucket brigade. The tub functioned as a reservoir and sometimes housed a hand-operated pump that forced water through a pipe or nozzle to waiting buckets. The invention of a hand-stitched leather hosepipe in the Netherlands about 1672 enabled fire fighters to work closer to the fire without endangering their engines and to increase the accuracy of water placement.
At about the same time the development of pumping devices made it possible to draw water from rivers and ponds. In the early 19th century copper rivets replaced the stitching on hoses, and 15-m (50-ft) lengths coupled with brass fittings enabled fire fighters to convey water through narrow passages, up stairways, and into buildings, while the pumps operated in the street. Cotton-covered rubber hose was developed around 1870. The steam-pump fire engine, introduced in London in 1829 by John Ericsson and John Braithwaite, was used in many large cities by the 1850s. Most steam pumpers were equipped with reciprocating piston pumps, although a few rotary pumps were used. Some were self-propelled, but most used horses for propulsion, conserving steam pressure for the pump. Steam fire engines were used in fighting the Chicago fire of 1871.
With the development of the internal-combustion engine early in the 20th century, pumpers became motorized. Because of problems in adapting geared rotary gasoline engines to pumps, the first gasoline-powered fire engines had two motors, one to drive the pump and the other to propel the vehicle. The first pumper using a single engine for pumping and propulsion was manufactured in the United States in 1907. By 1925 the steam pumper had been completely replaced by motorized pumpers. The pumps were originally of the piston or reciprocating type, but these were gradually replaced by rotary pumps and finally by centrifugal pumps, used by most modern pumpers.
At the same time, the pumper acquired its main characteristics: a powerful pump that can supply water in a large range of volumes and pressures; several thousand feet of fire hose, with short lengths of large-diameter hose for attachment to hydrants; and a water tank for the initial attack on a fire while fire fighters connect the pump to hydrants, and for areas where no water supply is available. In rural areas, pumpers carry suction hose to draw water from rivers and ponds. Current standards for pumper fire apparatus require that a fire pump have a minimum capacity of 2840 liters (750 gal) per minute at a pump pressure of 10.35 bar (150 psi). They also call for a water tank capacity of at least 1893 liters (500 gal).
Auxiliary vehicles are equipped with specialized equipment for effecting rescue, ventilating buildings, and salvage. Aerial ladders that typically extend to 30.5 m (100 ft) are carried on "hook and ladder" vehicles that also hold various kinds of tools and equipment, including heavy-duty jacks and air bags, extrication tools, oxyacetylene torches, self-contained breathing apparatus, and resuscitators. Other more basic equipment includes axes, shovels, picks, battering rams, power saws, hooks, and wrenches. Elevating platform trucks can raise fire fighters and equipment, including the water delivery system, as high as 30.5 m (100 ft). Rescue trucks carry a wide assortment of specialized emergency equipment, including the type that might be used in building collapses and cave-ins. Field communications units carry sophisticated electronic equipment for use in managing fire and emergency operations. Salvage trucks carry implements for reducing water damage, including large waterproof covers, dewatering devices, and tools for shutting off water flow from sprinkler heads. Hazardous materials response units are staffed with specially trained personnel equipped with protective clothing and monitoring devices for use at chemical spills and similar incidents.
Shipboard fires present special problems ranging from small fires in cabin cruisers to tanker fires involving thousands of metric tons of oil. Some of the special problems include complicated ship layouts, the danger of capsizing, and the difficulty of pinpointing and gaining access to the source of the fire. Fireboats, in sizes ranging from small, high-speed, jet-propelled rescue craft to large fire tugs, carry substantially all the fire-fighting equipment found on land apparatus. These include pumps, ladders, and rescue equipment, as well as special equipment necessary for marine fire fighting and water rescues, including rotating and angled nozzles, portable pumps, floating booms, foam-making apparatus, and special extinguishers such as carbon dioxide systems.
At the Fire
The basic tactics of fighting a fire can be divided into the following categories: rescue operations, protection of buildings exposed to the fire, confinement of the fire, extinguishing the fire, and salvage operations. The officer in charge, usually designated as the fireground commander, surveys the area and evaluates the relative importance of these categories. The commander also estimates what additional assistance or apparatus may be needed. Rescue operations are always given priority. Fire fighter safety has assumed increasing importance.
Once the fireground commander has appraised the situation, fire fighters and equipment are deployed. Pumper, ladder, and other truck companies, as well as rescue squads, are assigned to different areas of the fire, usually in accordance with the number and types of hose streams the fireground commander considers necessary to control the fire and prevent its spread.
In accordance with standard procedure for first alarms, fire companies go immediately to their assigned locations without waiting for specific orders. Special plans cover contingencies such as a fire covering a large area, a large building, or a particularly hazardous location. Usually on a first alarm one of the pumpers attacks the fire as quickly as possible, using preconnected hose lines supplied by the water tank in the truck, while larger hose lines are being attached to the hydrants. Members of the ladder and rescue companies force their way into the building, search for victims, ventilate the structure-break windows or cut holes in the roof to allow smoke and heat to escape-and perform salvage operations. Ventilating the structure helps to advance the hose lines with greater safety and ease, and also serves to safeguard persons who may still be trapped in the building.
Temperatures within a burning building may exceed 815¡ C (1500¡ F). Brightly burning fires principally generate heat, but smoldering fires also produce combustible gases that need only additional oxygen to burn with explosive force. The hazards to which fire fighters and occupants of a burning building are exposed include the breathing of superheated air, toxic smoke and gases, and oxygen-deficient air, as well as burns, injuries from jumping or falling, broken glass, falling objects, or collapsing structures. Handling a hose is difficult even before the line is charged with water under pressure. Nozzle reaction forces can amount to several hundred pounds, requiring the efforts of several people to direct a stream of water.
Types of Nozzles
Various nozzles are capable of projecting solid, heavy streams of water, curtains of spray, or fog. Fire trucks carry a selection of nozzles, which are used according to the amount of heat that must be absorbed. Nozzles can apply water in the form of streams, spray, or fog at rates of flow between 57 liters (15 gal) to more than 380 liters (more than 100 gal) per minute. Straight streams of water have greater reach and penetration, but fog absorbs heat more quickly because the water droplets present a greater surface area and distribute the water more widely. Fog nozzles may be used to disperse vapors from flammable liquids, although foam is generally used to extinguish fires in flammable liquids.
A variety of chemicals may be added to water to improve its ability to extinguish fires. Wetting agents added to water can reduce its surface tension. This makes the water more penetrating and facilitates the formation of small drops necessary for rapid heat absorption. By adding foam-producing chemicals and liquids to water, a fire-blanketing foam is produced. Foam is used to extinguish fires in combustible liquids, such as oil, petroleum, and tar, and for fighting fires at airports, refineries, and petroleum distribution facilities. A chemical additive can expand the volume of foam 1000 times. This high-expansion foam-water solution is useful in fighting fires in basements and other difficult-to-reach areas because the fire can be smothered quickly with relatively little water damage.
Salvage & Overhaul
This term refers to the methods by which fire fighters protect merchandise, household goods, and the interiors of buildings from smoke and water damage. Objects are covered with waterproof covers, and water is removed by water vacuums, mops, squeegees, water chutes, and portable pumps. Almost all fire departments carry salvage equipment in their apparatus. Fire departments in some large cities maintain special salvage companies.
Forest fires, often called wildland fires, are spread by the transfer of heat, in this case to grass, brush, shrubs, and trees. Because it is frequently difficult to extinguish a forest fire by attacking it directly, the principal effort of forest fire fighters is often directed toward controlling its spread by creating a gap, or firebreak, across which fire cannot move. Firebreaks are made, and the fire crews attempt to stop the fire by several methods: trenching, direct attack with hose streams, aerial bombing, spraying of fire-retarding chemicals, and controlled back-burning. As much as possible, advantage is taken of streams, open areas, and other natural obstacles when establishing a firebreak. Wide firebreaks may be dug with plows and bulldozers. The sides of the firebreaks are soaked with water or chemicals to slow the combustion process. Some parts of the fire may be allowed to burn themselves out.
Fire-fighting crews must be alert to prevent outbreaks of fire on the unburned side of the firebreaks. Fire-fighting crews are trained and organized to handle fires covering large areas. They establish incident command posts, commissaries, and supply depots. Two-way radios are used to control operations, and airplanes are employed to drop supplies as well as chemicals. Helicopters serve as command posts and transport fire fighters and their equipment to areas that cannot be reached quickly on the ground. Some severe wildfires have required more than 10,000 fire fighters to be engaged at the same time. The U.S. Forest Service maintains research laboratories, which develop improved fire-fighting equipment and techniques, and a school that trains fire fighters in the latest fire-fighting techniques. International conferences on wildland fire prevention and fire fighting have been held with greater frequency in recent years.
Private Fire Protection
Commercial and industrial buildings usually have some sort of internal, or private, fire-protection system installed.
A sprinkler system is an integrated system of underground and overhead piping, designed in accordance with fire protection engineering standards, and connected to one or more automatic water supplies. The system is usually activated by heat from a fire, and the sprinkler heads then discharge water over the fire area. Sprinkler systems are nearly 100 percent effective. Many sprinkler systems are supervised electrically from a central station, and alarms are transmitted to a fire department whenever the sprinklers operate or when a valve in the sprinkler system closes for any reason. If a fire-fighting unit arriving at a fire finds that the sprinkler system is not receiving sufficient water and pressure, a pumper is connected to the sprinkler system to supply additional water.
Many high-rise or other large buildings have an internal system of water mains (standpipes) connected to fire-hose stations. Trained occupants or employees of the building management operate the hoses until the fire department arrives. Fire fighters can also connect their hoses to outlets near the fire.
Buildings may also be equipped with detection systems that will transmit an alarm. Some detectors are designed to respond to smoke, and others to heat. In many jurisdictions, detection systems are required in public buildings, apartment houses, and sometimes even in private homes.
Two major types of smoke detectors are available. One is an ionization device that contains a small radioactive source for ionizing the air molecules between a pair of electrodes, permitting a very small current to flow between the pair. If smoke particles from a fire enter this space, they reduce the flow of current by adhering to the ionized molecules. The drop in current sets off a buzzer or other alarm.
The second type of smoke detector uses a photoelectric cell. In some of these detectors, smoke that enters obscures a steady beam of light; in others, the smoke scatters a light ray from a diode so that the cell can detect it. In either case the change sets off an alarm. The alarm may sound locally, or it may be designed to alert a central station with notification to the fire department. Photoelectric detectors are slower than ionization detectors, and sometimes both principles are combined. Both types can be run by batteries or by building current.
27 November 2010
The Now Famous Book And its Cover. (As a side note this is now and has always been one of my favorite books of all time.)