Glossary of Fire Fighting Terms

Adapter:  A hose coupling device for connecting hoses of the nominal size, but which have different type threads.

Air foam:  See mechanical foam.

Air foam nozzle (mechanical foam nozzle):  A special pick-up tube or nozzle incorporating a foam maker to aspirate air into the solution to produce air foam.

Air line mask:  A face mask where the air is supplied through an air hose attached to a blower outside of the contaminated space or area.

All-purpose nozzle (combination):  A mechanic

al device that fits on the end of a hose that controls the water pressure inside the hose three ways by operating a single valve. The three positions of the valve are:

1) FWD ­off,

2) Vertical-HV /L V fog and

3) Back solid stream.

Applicator:  A special pipe or nozzle attachment that fits into the all-purpose nozzle high velocity outlet. Applicators used aboard ship are 4′, 10′ and 12′ lengths and are equipped to change high velocity fog into low velocity fog. The 4′ and 10′ applicators fit the standard 1 1/2″ nozzles and the 4′ has a 60˚curve and the 10′ has a 90˚ curve on the outlet end. The 12′ applicator fits the standard 2 1/2″ nozzle and has a 90 ° curve at the outlet end.

Aqueous film forming foam (AFFF):  A fluorocarbon surfactant that acts as an effective vapor securing agent due to its effect on the surface tension of the water. Its physical properties enable it to float and spread across surfaces of a hydrocarbon fuel with more density than protein foam.

Arcing:  Pure electricity jumping across a gap in a circuit. The intense heat at the arc may ignite any nearby combustible material or may fuse the metal of the conductor.

Automatic alarm:  An alarm usually activated by thermostats, sprinkler valves or other automatic devices that activate electrical circuits to the control station located on the bridge.

Automatic sprinkler system:  A device that fulfills both the functions of a fire detecting system and a fire extinguishing system; the water is held back normally with a fixed temperature seal in the sprinkler head, which melts or shatters at a predetermined temperature.

Backup man:  The man positioned directly behind the nozzleman; he takes up the weight of the hose and absorbs some of the nozzle reaction so the nozzle can be manipulated without undue strain.

Bleve (pronounced “blevey”):  A boiling liquid expanding vapor explosion; failure of a liquefied flammable gas container caused by fire exposure.

Blitz attack:  Firefighters hit the fire with everything at their disposal.

Body harness:  A series of web straps on the protective breathing apparatus that position and stabilize the apparatus.

Boilover:  Occurs when the heat from a fire in a tank travels down to the bottom of the tank causing water that is already there to boil and push part of the tank’s contents over the side.

Breast plate:  That part of the protective breathing apparatus that holds the canister and protects the wearer from the heat generated by the unit.

Breathing apparatus:  A device that provides the user with breathing protection; it includes a facepiece, body harness and equipment that supplies air or oxygen.

Carbon dioxide (C02):  A heavy, colorless, odorless, asphyxiating gas that does not normally support combustion. It is one and one-half times heavier than air and when directed at the base of a fire its action is to dilute the fuel vapors to a lean mixture to extinguish the fire. Normally carried on board in 15 lb. portable extinguishers and 50lb or 100lb cylinders in the installed system.

Chain breaking:  A method of fire extinguishment that disrupts the chemical process that sustains the fire; an attack on the chain reaction side of the fire tetrahedron.

Chain reaction: Series of events, each of which cause or influence its succeeding event. For example, the burning vapor from a fire produces heat which releases and ignites more vapor; the additional vapor burns, producing more heat, which releases and ignites still more vapor; and so forth.

Check valve:  A valve that permits a flow in one direction only and will close to prevent a flow in the opposite direction.

Chemical foam:  Foam formed by mixing an alkali with an acid in water.

Class A fire:  A fire involving common combustible materials which can be extinguished by the use of water or water solutions. Materials in this category include wood and wood-based materials, cloth, paper, rubber and certain plastics.

Class B fire:  A fire involving flammable or combustible liquids, flammable gases, greases and similar products. Extinguishment is accomplished by cutting off the supply of oxygen to the fire or by preventing flammable vapors from being given off.

Class C fire:  A fire involving energized electrical equipment, conductors or appliances. Nonconducting extinguishing agents must be used for the protection of firefighters.

Class D fire:  A fire involving combustible metals, for example, sodium, potassium, magnesium, titanium and aluminum. Extinguishment is accomplished through the use of heat absorbing extinguishing agents such as certain dry powders that do not react with the burning metals.

Combination combustible gas and oxygen indicator:  An instrument that measures the concentrations of both combustible gas and oxygen; each is indicated on a separate meter.

Combination nozzle:  See all-purpose nozzle.

Combustible gas indicator:  An instrument used to determine whether the atmosphere of a particular area is flammable; also called an explosimeter.

Combustion:  See fire.

Compressed gas:  A gas that, at normal temperatures, is entirely in the gaseous state under pressure in its container.

Conduction:  The transfer of heat through a solid body.

Convection:  The transfer of heat through the motion of heated matter, that is, through the motion of smoke, hot air, heated gases produced by the fire and flying embers.

Convection cycle:  The pattern in which convected heat moves. As the hot air and gases rise from the fire, they begin to cool; as they do, they drop down to be reheated and rise again.

Cooling:  A method of fire extinguishment that reduces the temperature of the fuel below its ignition temperature; a direct attack on the heat side of a fire tetrahedron (also see fire tetrahedron).

Cryogenic gas:  A gas that is liquefied in its container at a temperature far below normal temperatures, and at low-to-moderate pressures.

Demand breathing apparatus:  A type of self-contained breathing apparatus that provides air or oxygen from a supply carried by the user.

Dry chemical:  A mixture of chemicals in powder form that has fire extinguishing properties.

Dry powder:  Extinguishing agents developed to control and extinguish fires in combustible metals (class D fires).

Dry system:  An automatic sprinkling system that has air under pressure throughout installed piping in areas that might be subjected to freezing temperatures. The operation of one or more sprinkler heads releases the air pressure and activates the control valve allowing water to flow into the system.

Electric fire sensor system:  A device capable of lighting a panel in the wheelhouse when it detects fire in a certain area of the ship.

Entry suit:  Protective clothing designed to protect the wearer from direct contact with flames for a short time.

Exhalation valve:  A simple one-way valve on a single-hose facepiece, consisting of a thin disk of rubber, neoprene or plastic resin secured in the center of the facepiece and designed to release exhaled breath; also called a flutter valve.

Explosimeter:  See combustible gas indicator.

Explosive range:  Flammable range; the range of the mixture of air and flammable gas or flammable vapor of liquids that must be present in the proper proportions for the mixture to be ignited. The range has upper and lower limits; any mixture above the upper explosive limit (VEL) or below the lower explosive limit (LEL) will not burn.

Exposures:  Combustible materials that may be ignited by flames or radiated heat from the fire.

Extinguisher:  Normally portable equipment approved for use on certain types and classes of fires.

Extinguishing agent:  A substance that will put out a fire and is available as a solid, liquid or gas.

Facepiece:  An assembly that fits onto the face of the person using the breathing apparatus, forming a tight seal to the face and transmitting air or oxygen to the user.

Fire:  A chemical reaction known as rapid oxidation that produces heat and light in the form of flames, gases and smoke.

Fire detector:  A device that gives a warning when fire occurs in the area protected by the device; it senses and sends a signal in response to heat, smoke, flame or any indication of fire.

Fire extinguisher:  A self-contained unit, portable or semi portable, consisting of a supply of the extinguishing agent, an expellant gas (if the apparatus is not pressurized) and a hose with a nozzle.

Fire extinguishing system:  A means of putting out fires consisting of a supply of the extinguishing agent, an actuation device (manual or automatic), and the piping, valves and nozzles necessary to apply the agent.

Fire gases:  The hot gases produced by burning materials.

Fire line automatic system:  The system used to detect fire in open spaces and to activate alarms and/or firefighting equipment automatically, for example, a pneumatic tube fire detector.

Fire-main system:  A system that supplies water to all areas of the vessel; it is composed of the fire pumps, piping (main and branch lines), control valves, hose and nozzles.

Fire point:  The temperature at which a liquid fuel sustains combustion.

Fire station:  Consists basically of a fire hydrant (water outlet) with valve and associated hose and nozzles.

Fire tetrahedron:  A solid figure with four triangular sides illustrating how the chain reaction sequence interacts with heat, fuel and oxygen to support and sustain a fire.

Fire triangle:  A three-sided figure illustrating the three essential components of fire: fuel (to vaporize, and burn), oxygen (to combine with fuel vapor), and heat (to raise the temperature of the fuel vapor to its ignition temperature).

Flame safety lamp:  An instrument used to test for oxygen deficiency; if there is enough oxygen in the surrounding atmosphere to keep the flame burning, there is enough oxygen to support life.

Flammable Range:  See explosive range.

Flashover:  The ignition of combustibles in an area heated by convection, radiation or a combination of the two. The action may be a sudden ignition in a particular location followed by rapid spread or a “flash” of the entire area.

Flash point:  The temperature at which a liquid fuel gives off sufficient vapor to form an ignitable mixture near its surface.

Flexible tubes:  The part of the facepiece designed to carry fresh air or oxygen from the canister to the facepiece and, in the facepiece with a dual hose, to return exhaled breath from the facepiece to the canister.

Flutter Valve:  See exhalation valve.

Foam:  A blanket of bubbles that extinguishes fire mainly by smothering. The blanket prevents flammable vapors from leaving the surface of the fire and prevents oxygen from reaching the fuel. The water in the foam also has a cooling effect.

Foam concentrate:  Liquids of 3 % or 6 % concentrations that are mixed with water to produce mechanical foam.

Foam generators:  Devices for mixing chemical foam powders with a stream of water to produce foam. Pressure type foam generators are closed devices containing the necessary chemicals with provision for admission of water when foam is needed.

Foam proportioner:  A device that regulates the amount of foam concentrate and water to form a foam solution.

Foam solutions:  The result of mixing foam concentrates with water.

Fog (spray) streams:  A method of projecting a stream of water in which a specifically designed nozzle causes the water to leave the nozzle in small droplets, thereby increasing the water’s heat absorption efficiency.

Fresh-air breathing apparatus:  A hose mask; a facepiece connected to a pump by a long hose through which air is pumped to the user. Mobility is limited by the length and weight of the hose.

Fuel:  Any combustible material adding to the magnitude or intensity of a fire; one of the essential sides of the fire triangle.

Fumes:  A smoke, vapor or gas given off by a fire which could be irritating, offensive or dangerous to the fire fighter.

Gas:  A substance that has no shape of its own but which will take the shape of, and fill the volume of its container.

Gas free:  An area, tank or system previously used to carry inflammable or poisonous liquids that has been entirely cleared of such liquids and certified by a chemist as clear of any danger.

Gasket:  A sealing ring necessary to make a watertight connection between female and male hose couplings.

Gas mask:  A device that filters contaminants from air that is to be breathed; it can only be used in an atmosphere that contains enough oxygen to support life.

Goosenecking:  Directing a stream of water over the vessel’s side, perpendicular to the water surface.

GPM:    the initials for “Gallons Per Minute” and is a measure of water flow through the fire main system.

Halogenated extinguishing agents:  Halon; made up of carbon and one or more of the halogen elements: fluorine, chlorine, bromine and iodine.

Halon:  See halogenated extinguishing agents.

Hazard:  A condition of fire potential defined by arrangement, size, type of fuel and other factors which form a special threat of ignition or difficulty of extinguishment. A “fire hazard” refers specifically to fire seriousness potential and a “life hazard” to danger of loss of life from fire.

Head harness:  That part of the mask designed to hold the facepiece in the proper position on the face, with just enough pressure to prevent leakage around the edge of the mask.

Heat:  temperature above the normal atmospheric temperature, as produced by the burning or oxidation process; one of the essential sides of the fire triangle; often referred to as “ignition temperature” in fire fighting instructions.

Heat transfer:  The movement and dispersion of heat from a fire area to the outside atmosphere. An example of heat transfer would be fire fighting water being converted into steam and expanding its volume, thus creating a slight pressure and carrying the heat and heated water vapor to the outside atmosphere also see connection, conduction, and radiation.

High-expansion foam:  A foam that expands in ratios of over 100: 1 when mixed with water; it is designed for fires in confined spaces.

High pressure fog (high velocity fog):  Produced when using the all purpose nozzle with the handle in mid-position. It is a high capacity jet spray produced at very high pressure and discharged through small holes of a cage type sprayer tip.

Hose:  A flexible tube used to carry fluid from a source to an outlet. Standard shipboard fire hoses are 1 1/2″ or 2 1/2″ in diameter. They are normally 50 feet in length, with a female coupling installed on one end and a male coupling on the other.

Hose jackets:  The covering over the inside liner of a hose. It is a woven jacket (or jackets) of cotton or synthetic fibers.

Hose mask:  See fresh-air breathing apparatus.

Hose reel:  a permanently mounted fire hose installation which stows a fire hose in a ready position. Normally found in engine spaces aboard ship.

Hose spanner:  See spanner wrench.

Hyperthermia:  A dangerously high fever that can damage nerve centers. This condition can result from exposure to excessive heat over an extended period of time.

Ignitable mixture:  Mixture of vapor and air that is capable of being ignited by an ignition source, but usually is not sufficient to sustain combustion.

Ignition temperature:  The lowest temperature at which a fuel will burn without continued application of an ignition source.

Jury rigging:  Overloading electrical wiring by trying to operate too many appliances from it.

Lens:  That part of the facepiece that allows the wearer a wide range of vision.

Liquefied gas:  A gas that, at normal temperatures, is partly in the liquid state and partly in the gaseous state under pressure in its container.

LNG (liquid natural gas):  A natural gas, a hydrocarbon of fossil fuel, consisting mainly of methane stored as a liquid and vaporized and burned as gas.

Lower flammable limit:  Minimum flammable concentration of a particular gas in the air.

Low velocity fog (low pressure fog):  Produced by inserting an applicator into an all purpose nozzle. It is a high capacity, low pressure mist discharged at angles from 600 to 90 degrees; used to cool down an area or to protect the fire fighting team from flames or smoke.

LPG (liquefied petroleum gas):  Anyone of several petroleum products such as “butane” or “propane” stored under pressure as a liquid and vaporized and burned as gas.

Male coupling:  An outside threaded hose nipple which fits into the threads of a swivel coupling of the same pitch and appropriate diameter. A coupling to which nozzles and other appliances are attached.

Mechanical foam:  Air foam; foam produced by mixing a foam concentrate with water to produce a foam solution.

Monitor (sentinel):  A large stream nozzle, normally found on tankers, fixed in various locations above the main deck. They are operated by gear-driven wheels or handles and have a 3600 arc. Can deliver a stream of water or foam onto a deck type fire.

National standard thread:  All fire hose fittings and coupling screw threads are national standard. The standard 21h” has 71/2 threads to the inch and the outside diameter of the male couplings is 3 1 / 16″.

Noncombustible:  Not subject to combustion under ordinary conditions of temperature and normal oxygen content of atmosphere.

Noncombustible material:  One that will not burn or support combustion.

Nose cup:  An optional, removable part of the facepiece that fits into the exhalation valve and is designed to reduce fogging of the lens.

Nozzle:  A device with a control valve attached to the hose outlet to shape and direct the stream.

Nozzleman:  The key member and leader of the hose team who controls the nozzle and directs the stream onto the fire.

Overhaul:  A procedure following a fire whereby the area is examined for hidden fire and fire extension and the fire area is cleaned up.

Oxidation:  A chemical process in which a substance combines with oxygen, giving off energy usually in the form of heat. The rusting of iron is an example of slow oxidation; fire is an example of rapid oxidation.

Oxidizing substance:  A material that releases oxygen when it is heated or, in some instances, when it comes in contact with water. Substances of this nature include: hypochlorites, chlorates, perchlorates, nitrates, chromates, oxides and peroxides. Burning oxidizers cannot be extinguished by removing their oxygen; extinguishment must be accomplished by application of large amounts of water.

Oxygen:  A gas present in the atmosphere in about 21 % concentrations, which while not combustible is an essential element for combustion. It is also the essential gas in respi­ration since the oxidation process is basic to life.

Oxygen breathing apparatus (OBA):  a type of self-contained breathing apparatus that provides oxygen chemically.

Oxygen deficiency:  Less than 16 % oxygen content in the atmosphere. Oxygen deficiency can be caused by smoke, heat or gases of a fire.

Oxygen dilution:  A method of fire extinguishment that reduces the amount of available oxygen below that needed to sustain combustion; an attack on the oxygen side of the fire tetrahedron (also see fire tetrahedron).

Oxygen indicator:  An instrument used to determine whether the atmosphere contains sufficient oxygen (15% or more) to sustain life.

Payout:  When hose is fed to the hose team to prevent excessive strain on the firefighters. Normally hose is paid out by the backup men on the hose.

Petroleum products:  Oils made by distillation (heating) of crude petroleum which produce such products as gasoline, kerosene, fuel oil, lubricating oil and asphalt.

Pick-up unit:  The small tube with a metal end used to deliver the foam concentrate from its storage (can) to the air foam nozzle.

Pike-head fire axe:  A versatile, portable. Firefighting tool with a blade and a pike end.

Pneumatic tube fire detector:   see fire line automatic system.

Portable fire extinguisher:  One that can be carried to the fire area for a fast attack; it contains a limited supply of extinguishing agent.

Portable pump:  A small gasoline driven pump used in emergencies to deliver water to a fire, independent of the ship’s fire main system.

Protective clothing:  A general term used to describe the ensemble of gear a firefighter wears. Includes boots, foul weather gear, gloves, hat or special heat-resistant suits.

Proximity suit:  Protective clothing that encases the wearer in a heat resistant envelope and is worn when it is necessary to approach the fire closely; it does not protect the wearer during direct contact with flames.

Pyrolysis:  The conversion of solid fuel to flammable vapor by heat.

Pyrometer:  An instrument for measuring temperatures too great for an ordinary thermometer; it is used to find the temperature of a fire.

Quench:  To put out; to extinguish by soaking the fuel with water or cooling the fuel down below ignition temperature.

Radiant heat:  Pure energy; the heat that is released in the burning process. Like the heat of the sun, it radiates, or travels, in all directions.

Radiation:  The travel of heat through space.

Radiation feedback:  The heat from a fire that radiates back to the fuel causing increased vapor production.

Rapid water:  Slippery water; water to which small quantities of polyethylene oxide have been added to reduce its viscosity and its friction in hose lines, thereby increasing the reach of the stream.

Reach:  The distance a straight stream travels before breaking up or dropping.

Reducer:  A coupling used to attach a smaller diameter hose to a larger diameter hose or outlet and vice versa.

Reid vapor pressure method:  Method used by the American Society of Testing Materials to test vapor pressure. It is a measure of the volatility, or tendency to vaporize, of a liquid.

Seat of fire:  The area where the main body of the fire is located. It is determined by the outward movement of heat and gases and where the fire has burned through the deepest.

Self-closing fire door:  a fire resistant door (normally kept closed) which, when opened, is returned to a closed position by a closing device.

Self-contained breathing apparatus: (SCBA):  A device providing air or oxygen to the user who wears the entire device; thus the user is completely mobile. However, the device can supply air or oxygen for only a limited amount of time.

Semiportable fire extinguisher:  One from which a hose can be run out to the fire. The other components are fixed in place.

Smoke:  A visible product of fire made up of carbon and other unburned substances in the form of suspended particles. It also carries the vapors of water, acids and other chemicals, which can be poisonous or irritating when inhaled.

Smoke detection system:  A device that samples the air to detect the presence of smoke particles in the monitored area, and then sends an alarm.

Smoldering:  To burn and smoke without flame, to exist ill a state of suppressed activity.

Smothering:  A method of fire extinguishment that separates the fuel from the oxygen; an attack on the edge of the fire tetrahedron where the fuel and oxygen sides meet (also see fire tetrahedron).

Solid stream:  See straight stream.

Spanner wrench:  A special tool designed specifically for tightening or breaking apart fire-hose connections.

Speaking diaphragm:  That part of the facepiece, located directly in front of the wearer’s mouth that projects the wearer’s voice with little or no distortion.

Spill fire:  When burning flammable liquids spill onto the deck. Often involves intense flame and heat due to the relatively large surface for evaporation of liquids.

Spontaneous ignition:  A fire that occurs without a flame, spark, hot surface or other outside source of ignition.

Static electricity:  Charges of electricity accumulated on opposing and usually moving surfaces having negative and positive charges, respectively. A hazard exists where the static potential is sufficient to discharge a spark in the presence of flammable vapors or combustible dusts.

Static pressure:  The water pressure available at a specific location where no flow is being used and where there are no pressure losses due to friction.

Station bill:  A muster list outlining the special duties and duty station of each member of the crew during emergencies, as well as the signals for these emergencies.

Steam smothering:  an installed system found on older ships used to protect spaces where fire was likely to occur, such as engine room, cargo spaces, paint lockers, and so forth.

Slopover:  An event that occurs when water is introduced into a tank of very hot liquid, causing the liquid to froth and spatter.

Straight stream:  Solid stream; a method of projecting a stream of water formed by a nozzle that is fitted to a fire hose. The nozzle is tapered to a size less than one-half the diameter of the hose end. This smaller opening increases the velocity of the water and gives it greater throwing power.

Strainers:  Wire or metal cages installed in the fire main system to keep debris from clogging up the lines. Some strainers are located at the fire stations for periodic cleaning out purposes.

Thermal lag:  the difference between the temperature of the surrounding air and the temperature necessary to activate the fire detector.

Thick water:  Water that has been treated with a chemical to decrease its ability to flow. It thus forms a thick wall that clings to burning material and remains in place longer than ordinary water.

Tri-gate:  A device used to reduce the hoseline size and provide three outlets.

Wet water:  water that has been treated with a chemical agent to lower its surface tension, thus allowing it to penetrate porous materials more easily.

Wheatstone bridge:  A device for measuring electrical resistance.

Wye gate:  A device in the shape of a “Y” used to reduce the hoseline size and separate the lines.

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