Firefighter Dictionary: C

The following is common terminology to structural fire firefighters. There are additional definitions for emergency medical terminology, building construction, arson investigation and hazardous materials and more. Please note that some definitions have more than one meaning but are spelled the same. Click on a letter to take you to that index.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 

C

C

Degrees Celsius, centigrade.

Cable hanger

A device used to test the structural strength of aerial ladders.

Cache

A pre-determined complement of tools, equipment, and/or supplies stored in a designated location, available for incident use

Caisson

A 10" or 12" diameter hole drilled into the earth and embedded into bedrock 3 - 4 feet. The structural support for a type of foundation wall, porch, patio, monopost, or other structure. Two or more "sticks" of reinforcing bars (rebar) are inserted into and run the full length of the hole and concrete is poured into the caisson hole

Cal

 Abbreviation for Calorie.

Calibrate

To standardize or adjust the increments on a measuring instrument.

Calorie (cal)

The quantity of heat required to raise the temperature of 1 gram of water 1 degree Celsius. calorimeter A device for measuring the energy absorbed from a source of electromagnetic radiation.

CAMEO

Acronym for  Computer-Aided Management of Emergency Operations.

Camp

A geographical site, within the general incident area, separate from the Incident Base, equipped and staffed to provide sleeping, food, water, and sanitary services to incident personnel.

Candlepower (cp)

The unit of light intensity or brightness of a standard candle at hrs

Canister (Respirator)

A container filled with a sorbet, and possibly catalysts, used for removing contaminants (gases or vapors) from air being inspired through the device.

Canister, oxygen generated

A container of chemicals that create oxygen when the individual's breath is mixed with them. Similar to all service masks. This is old technology and for the most part have been taken out of service due to the heat the canisters generate. The canisters were known to explode when the heated can came in contact with water.

Cannula (Nasal)

A device consisting of two short tubes that can be inserted into the nostrils for administering oxygen or other therapeutic gases.

Canopy

A projection over windows and doors to protect them from the weather.

Canopy hood

A one- or two-sided hood which is positioned above an operation that typically involves heating, to receive and remove the hot air and contaminants that are released and rise and enter the hood.

Canteen unit 

Emergency vehicle that provides food, drinks and other rehabilitative service to emergency workers at extended incidents. These services have been provided to some fire departments from the American Red Cross and the Salvation Army.

Cantilever

A projecting beam or structural member anchored at only one end. An overhang. Where one floor extends beyond and over a foundation wall. For example at a fireplace location or bay window cantilever. Normally, not extending over 2 feet.

Cap

The upper member of a column, pilaster, door cornice, molding, or fireplace.

Cap flashing

The portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.

Cap sheet

A finish saturated roofing felt used as a covering for a roof.

Capacity

Maximum ability of a pump or water distribution system to deliver water.

Capillary

Pertaining to or resembling a hair with a very small internal diameter. One of the minute blood vessels that connect the arteries and veins. 

Captain

Officer in charge of a fire station, or any other position of comparable responsibility in the department. The highest rank in an individual company unit.

Car

Radio term for officer’s vehicle. Some ambulance services refer to their vehicles as cars

Carbon dioxide (CO2)

A gas stored in cylinders and applied through a fixed or semi fixed system, of from a portable extinguisher. It is useful for inerting a closed area or for putting out small local fires. A heavier than air gas used in extinguishing Class B fires by smothering, or by displacing the oxygen. A fire gas produced by the complete combustion of a carbonaceous material. In solid form, a super cool temperature it is known as dry ice. A odorless, colorless gas, which can at high levels (above 1.5% or 15,000 parts per million), have physiological effects. Main indoor source is human respiration; measurements used as indicators of ventilation conditions.

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Carbon monoxide (CO)  

Carbon Monoxide is a colorless gas which has almost no odor. It is like smoke in that it is a product of incomplete combustion. Carbon monoxide is the by product of the burning of any material containing carbon in the solid liquid or gaseous state. Almost all of the fires encountered by firemen and fire investigators will involve certain amounts of carbon monoxide and smoke. It is a chemical asphyxiant; in the bloodstream it effectively prevents the transport of oxygen to the body's tissues. CO exposure can affect the lungs, heart, and nervous system, and can cause death. Sources include cooking and heating appliances, tobacco smoke, and entrained exhaust from parking garages and truck idling areas.

Carbonaceous

A material made of, or containing carbon. This includes almost every flammable material.

Carboy 

A container, usually encased in a protective basket or crate, to ship hazardous materials, particularly corrosives.

Carcinogen

An agent that produces or is suspected of producing cancer. A material that either causes cancer in humans or, because it causes cancer in animals, is considered capable of causing cancer in humans.

Cardio-pulmonary resuscitation (CPR)

A combination of artificial resuscitation and closed-chest cardiac (heart) compression

Cargo manifest

A shipping paper that contains all of the contents being carried by the transporting vehicle or vessel.

Carport

An automobile shelter not fully enclosed.

Carriage 

The horizontal part of the stringers of a stair that supports the treads.

Cartridge respirator

 A respirator using various chemical substances to purify inhaled air of certain contaminative gases and vapors. Typically effective for concentrations no more than 10 times the TLV for a half face piece and 100 times the TLV for a full-face piece, provided the contaminant has warning properties (odor or irritation) near the TLV.

CAS registry number

The American Chemical Society (ACS) uniquely assigns Chemical Abstracts Service (CAS) Numbers to molecules and mixtures. CAS numbers are often used by local and state hazardous materials compliance legislation for tracking chemicals in the workplace and in the community. These numbers provide a unique identification for chemicals as well as a means for crosschecking chemical names.

Cascade air cylinders

Large air cylinders that are used to refill smaller SCBA cylinders.

Cascade System

Personnel working in a hazardous area and wearing an SCBA are limited to around 30 minutes of breathing air by the size of the cylinder (usually 2500 psi) and their respiratory rate. When the cylinders are empty they must be refilled in order to be used again. A cascade system refers to larger capacity cylinders (between 4500 and 6000 psi) linked together and refilled by a compressor. The used SCBA cylinders are then connected to this system to be refilled. Many departments have the capability to do this on the scene and all have refill systems at their stations. Three or more large air cylinders, each usually with a capacity of 300 cubic feet (8490 L), that are interconnected and from which smaller SCBA cylinders are recharged

Casement

Frames of wood or metal enclosing part (or all) of a window sash. May be opened by means of hinges affixed to the vertical edges.

Casement window

A hinged window that opens out, usually made of metal. A window with hinges on one of the vertical sides and swings open like a normal door

Casing 

A covering put around something; a case. Trim around window and door openings. A steel pipe used as a lining in an oil well.

Catalyst 

A material that alters the energy necessary to produce a chemical reaction. If the energy is lowered, the reaction proceeds more quickly (the typical use for a catalyst). If the energy necessary is increased, the reaction is slowed. The catalyst is not consumed by the chemical reaction.

Catch a hydrant

The firefighter gets off the fire apparatus at the hydrant, connects a large diameter fire hose to the hydrant and turns on the water (hydrant) to supply the engine company with water.

Catch basin

 See Portable Tank.

Cause                                   

The circumstances, conditions, or agencies that bring together a fuel, ignition source, and oxidizer (such as air or oxygen) resulting in a fire or a combustion explosion.

Caustic

Burning or corrosive. A hydroxide of a light metal. Broadly, any compound having highly basic properties. A compound that readily ionizes in aqueous solution to yield OH-anions, with a pH above 7, and turns litmus paper blue. See Alkaline, Base.

Cavitation

If pressure at any point inside a pump drops below the vapor pressure corresponding to the temperature of the liquid, the liquid will vaporize and form cavities of vapor. The vapor bubbles are carried along with the stream until it reaches a region of higher pressure. Then they collapse or implode with a tremendous shock on the adjacent impeller walls.

Cavity wall

Double masonry wall having an air space between the wyths. A wyth is each continuous vertical section of masonry one unit in thickness

CCA (Chromated Copper Arsenate)

A pesticide that is forced into wood under high pressure to protect it from termites, other wood boring insects, and decay caused by fungus

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CDC (Center for Disease Control)

This Department of Health and Human Services agency includes the National Center for Chronic Disease Prevention and Health Promotion; National Center for Environmental Health; National Center for Health Statistics; National Center for HIV, STD and TS Prevention; National Center for Infectious Diseases; National Center for Injury Prevention and Control; National Institute for Occupational Safety and Health; Epidemiology Program Office; International Health Program Office; Public Health Practice Program Office; and the National Immunization Program.

Cedar shingles

Roofing and siding shingles made from western red cedar.

Ceiling exposure value

The maximum airborne concentration of a biological or chemical agent to which a worker may be exposed at any time.

Ceiling joist

One of a series of parallel framing members used to support ceiling loads and supported in turn by larger beams, girders or bearing walls. Also called roof joists.

Ceiling layer

A buoyant layer of hot gases and smoke produced by a fire in a compartment.

Ceiling limit

An occupational exposure limit that must not be exceeded at any time. Both OSHA and NIOSH state that exposure to continuous, varying, intermittent or impulsive noise shall not exceed 140 dBA.

Ceiling plenum

The space between the suspended and structural ceiling, used as part of the air distribution system. This space usually accommodates electrical, communications, and mechanical connections as well.

Cellar pipe

Special nozzle for attacking fires in basements, cellars, and other spaces below ground level.

Cellular asphyxiant

A material that upon entering the body inhibits the normal function of cells. Examples are CO, hydrogen cyanide, or hydrogen sulfide poisoning.

Cement

The gray powder that is the "glue" in concrete. Portland cement. Also, any adhesive.

Central Fire Station

Headquarters station that contains administrative offices, special equipment, fire apparatus, and personnel.

Central Nervous System (CNS)

In humans, the brain and spinal cord, as opposed to the peripheral nerves found in the fingers, etc.

Centrifugal pump

 A fire pump using centrifugal force (force to the outside) to develop and impart velocity to the water as it passes through the pump. There are single and multistage centrifugal pumps. Pump with one or more impellers that utilize centrifugal force to move the water. Most modern fire pumps are of this type.

CERCLA

Acronym for Comprehensive Environmental Response, Compensation, and Liability Act.

Certificate of Occupancy (CO)

An abbreviation for "Certificate of Occupancy". This certificate is issued by the local municipality and is required before anyone can occupy and live within the home. It is issued only after the local municipality has made all inspections and all monies and fees have been paid.

Certification tests

Pre-service tests for aerial device, ladder, pump, and other equipment conducted by an independent testing laboratory prior to delivery of an apparatus. These tests assure that the apparatus or equipment will perform as expected after being placed into service.

C-Factor

Numerical value factor that indicates the roughness of the inner surface of piping or fire hose. Used for calculating how friction loss affects gallons per minute. There are several formulas for computing the carrying capacities of water mains.  The one most commonly used in the water works industry is the Hazen-Williams Formula.  A factor called "C" represents the coefficient of  friction.  It is a measure of the roughness of the interior surface of pipe.  A "C" factor of 140 would indicate a very smooth pipe, whereas a "C" factor of 70  would indicate a very rough pipe.  The smoother the surface of the pipe wall, the larger the value of "C" and, consequently, the greater the carrying capacity.

CFM 

Abbreviation for cubic feet per minute. A rating that expresses the amount of air a blower or fan can move. The volume of air (measured in cubic feet) that can pass through an opening in one minute.

CFR

Crash, Fire Rescue personnel; trained in aircraft firefighting and rescue. Code of Federal Regulations; enforced by federal and state agencies and containing statutes for the function of federal government.

CGI 

See Combustible Gas Indicator.

Chafing block

Blocks placed under hose lines to protect the hose covering from damage due to rubbing against the ground or concrete.

Chain hose tools

Chain, strap, and rope hose tools used to carry, secure, and otherwise aid in handling hose.

Chain of Command

A series of command, control, executive, or management positions in hierarchical order of authority. The order of rank and authority in the fire service.

Chain reaction

A series of self sustaining changes each of which causes or influences a similar reaction. See tetrahedron.

Chair rail

Interior trim material installed about 3-4 feet up the wall, horizontally.

Char 

Carbonaceous material that has been burned and has a blackened appearance.

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Char blistering

Convex segments of carbonized material separated by cracks or crevasses that from on the surface of char, forming on materials such as wood as the result of pyrolysis or burning. See Alligatoring.

Charge

The act of pressurizing a fire hose or fire extinguisher.

Charged building

A building heavily laden with smoke and gases, and possibly in danger of having a backdraft.

Charged Hose

A line that has been pressurized by the pump operator so that it is ready for use by the firefighting personnel.

Charged line

Hose loaded with water under pressure and prepared for use.

Charles's Law

 If the volume of a gas is kept constant and the temperature is increased, the pressure increases in direct proportion to the increase in absolute temperature. A gas will expand or contract in direct proportion to increase or decrease in temperature. If a gas is confined so that it will not expand, its pressure will increase or decrease in direct proportion to temperature.

Chase

A framed enclosed space around a flue pipe or a channel in a wall, or through a ceiling for something to lie in or pass through.

Chauffeur

See Fire Apparatus Driver/ Operator.

Check valve

An automatic valve that permits flow in only one direction.

Check-In

The process whereby resources first report to an incident. Check-in locations include: Incident Command Post (Resources Unit), Incident Base, Camps, Staging Areas, Helibases, Helispots, and Division Supervisors (for direct line assignments).

Checking the building

Fire size-up term used when equipment arrives on the scene of an incident and no fire or smoke are visible. The act of determining if there is an actual fire. Same as Investigation.

Checklist 

Detailed lists generally prepared for the maintenance of equipment or apparatus, or for installed fire protection equipment to ensure that the inspector does not over­look an item that needs to be checked regularly. They may also be used during pre-fire planning and fire prevention inspections.

Chemical burn                   

A burn that occurs when the skin comes into contact with strong acids, strong alkalis, or other corrosive materials. These agents literally eat through the skin and in many cases continue to do damage so long as they remain in contact with the skin.

Chemical Chain Reaction

Vapor or gases are distilled from flammable materials during initial burning. Atoms and molecules are released from these vapors and combine with other radicals to form new compounds. These compounds are again disturbed by the heat releasing more atoms and radicals that again form new compounds and so on. See tetrahedron.

Chemical compound

A new homogeneous substance consisting of two or more elements and having properties different from the constituent elements.

Chemical foam

A foam formed when an alkaline solution and an acid solution unite to form a gas (carbon dioxide) in the presence of a foaming agent that traps the gas in fire-resistive bubbles.

Chemical name 

The scientific designation of a chemical or a name that clearly identifies the chemical for hazard evaluation purposes. All pharmaceuticals have a chemical name, generic name and a product name.

Chemical properties

Properties of a material that relate to toxicity, flammability, or chemical reactivity. A property of matter that describes how it reacts with other substances.

Chemical reaction

A process that involves the bonding, unbonding, or rebonding of atoms. A chemical change takes place that actually changes substances into other substances.

CHEMTREC

Abbreviation for the Chemical Transportation Emergency Center. Established in Washington, D.C., by the Chemical Manufacturers Association (CMA) to provide emergency information on materials involved in transportation accidents. CHEMTREC can contact the shipper or producer of the material for more detailed information on the chemical released, to facilitate response and cleanup actions. 24-hour number: (800) 424-9300. In Washington D.C., Alaska, or Hawaii call (202) 483-7616.

Chief 

The ICS title for individuals responsible for management of functional Sections: Operations, Planning, Logistics, Finance/Administration and Intelligence (if established as a separate section). A fire department officer of greater than company officer rank. The chief administrative officer of the fire department and chief command officer at any fire

Chief of Department 

The highest ranking member of the fire department; in some instances, designated as the director or administrator.

Chief Officer

Any of the higher officer grades, from district or battalion chief to the chief of the fire department.

Chimney Bucket

The name given to the container which normally holds a chimney chain, a small shovel, and fire retardant gloves. The chain is taken out and the bucket and shovel are taken inside the structure to remove anything that may still be burning in the fireplace. This is done in order to aid in the extinguishment of a chimney fire.

Chimney Chain

This is a special chain that has a number of smaller chains attached to one end. While in communication with the fire personnel inside of the structure the chain is dropped down the chimney and spun in a circular pattern to remove the burning creosote from the chimney lining. It is then gathered into the chimney bucket by the fire personnel inside of the structure and taken outside for extinguishment.

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Chink

To install fiberglass insulation around all exterior door and window frames, wall corners, and small gaps in the exterior wall.

Chip Board

A manufactured wood panel made out of 1"- 2" wood chips and glue. Often used as a substitute for plywood in the exterior wall and roof sheathing. Also called OSB (Oriented Strand Board) or wafer board.

Chlorep

The chlorine emergency plan, established by the Chlorine Institute, enables the nearest producer of chlorine to respond to an incident involving chlorine. (Contact is made through CHEMTREC.)

Chlorine kits

Standardized kits commercially manufactured by contract with the Chlorine Institute to provide equipment to control or stop leaks in chlorine cylinders, tanks and transportation tank cars. These kits come in different sizes depending on what type of container or vessel the chlorine is in at the time of the leak.

Chocks

 Wooden, plastic, or metal blocks constructed to fit the curvature of a tire; placed against the tire to prevent apparatus rolling.

Chronic effects

An adverse health effect on a human or animal body with symptoms that develop slowly or that recur frequently due to the exposure of hazardous chemicals.

Chronic exposure

Low doses repeatedly received by the body over a long period of time. Repeated doses or exposure to a material over a relatively prolonged period of time.

Chronic Obstructive Pulmonary Disease (COPD)

A chronic obstruction of bronchial airflow resulting in decreased pulmonary ventilation.

Chronic poisoning

Poisoning that is a result of repeated exposure to sub-lethal doses over a period of time.

Chuck 

 A portable fire hydrant carried on the apparatus with one or more gated connections for fire hose. The device screws into a special flush hydrant connection on the water main or a special main. Also an air line connection.

Church raise

See auditorium raise.

Chutes

A channel constructed of salvage covers for water runoff. Also a means of escape from large aircraft.

Circuit 

The path of electrical flow from a power source through an outlet and back to ground.

Circuit Breakers

A circuit breaker is a part of the electrical path. It operates much like a switch, except it opens automatically when a predetermined amount of electricity passes through it. Circuit breakers usually operate when moderate overloads occur for continuous periods by means of a thermally responsive element and when very high electrical values are reached by means of a magnetically responsive element. The magnetic element is not affected by temperature, but the thermal element will have different response times in different ambient temperatures. A device which looks like a switch and is usually located inside the electrical breaker panel or circuit breaker box. It is designed to (1) shut of the power to portions or all of the house and (2) to limit the amount of power flowing through a circuit (measured in amperes). 110 volt household circuits require a fuse or circuit breaker with a rating of 15 or a maximum of 20 amps. 220 volt circuits may be designed for higher amperage loads e.g. a hot water heater may be designed for a 30 amp load and would therefore need a 30 amp fuse or breaker.

Circulating feed

Fire hydrant that receives water from two or more directions.

Circulating relief valve

Small relief valve that opens and provides enough water flow into and out of the pump to prevent the pump from overheating when it is operating at churn against a closed system

Circulating system

See Loop System.

Circulator valve

Device in a pump that routes water from the pump to the supply to keep the pump cool when hose lines are shut down.

Circumstantial evidence

Facts from which presumptions or inferences are made. Indirect evidence. (For example, seeing a person flee from the scene of a crime is circumstantial, indirect evidence that the person committed the crime; seeing a person commit a crime is direct evidence.)

Cistern 

A water storage container, usually below grade level, for emergency use including fire protection.

Clapper valve

Hinged valve that permits the flow of water in one direction only.

Class A combustibles         

Ordinary combustibles, which leave a residue after burning.

Class A explosive

A material or device that presents a maximum hazard through detonation.

Class A fire

Refers to a fire involving ordinary combustibles such as wood, paper, cloth, and so on that is best extinguished by cooling action (water).

Class A foam 

Foam specially designed for use on Class A combustibles. Class A foams are essentially wetting agents that reduce the surface tension of water and allow it to soak into combustible materials easier than plain water.

Class A poison

A poisonous gas or liquid of such nature that a very small amount of the gas, or vapor of the liquid, is dangerous to life.

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Class B combustible

Flammable liquids and gases.

Class B explosive

A material or device that presents a flammable hazard and functions by deflagration

Class B fire

Refers to fires of flammable and combustible liquids, and gases like gasoline, kerosene, and propane. They are usually extinguished by smothering agents (dry chemical—CO2).

Class B foam 

Foam specially designed for use on Class B flammable and combustible liquids. New variants are designed for polar solvents. Types include AFFF and AR-AFFF.

Class B poison

A substance that is known to be so toxic to human life that it affords a severe health hazard during transportation.

Class C combustibles

Class A or B fires that occur in or near electrical equipment.

Class C explosive

A material or device that contains restricted quantities of either Class A or Class B explosives or both, but presents a minimum hazard.

Class C fire

Refers to a fire involving energized electrical equipment. Do NOT use water to extinguish)

Class D combustibles       

Combustible metals that are easily oxidized.

Class D fire

Refers to fires of combustible metals like magnesium, sodium, and titanium.

Classes of fires

See fires or review Class A, B, C and D fires defined above 

Claw tool

A forcible entry tool having a hook and a fulcrum at one end and a prying blade at the other.

Clean Burn 

A fire pattern on surfaces where soot has been burned away.

Clean out  

An opening providing access to a drain line. Closed with a threaded plug.

Clean room

A description of a room where specialized monitoring and filtering reduces the air born particulates and air cleanliness to a specific micron standard. Clean rooms are designed for high value electronics, electronic component construction and medical research.

Clear Text

The use of plain English in radio communications transmissions. No Ten Codes or agency-specific codes are used when utilizing clear text.

Clip ties

Sharp, cut metal wires that protrude out of a concrete foundation wall (that at one time held the foundation form panels in place).

Closed circuit breathing apparatus

Self-contained respiratory protective device in which the wearer’s exhalations are recycled. Carbon dioxide and moisture are removed from the exhalation and, after some oxygen is added, the wearer rebreathes the exhalation. Hence also known as rebreather apparatus.

Closet Hook

Similar in use to a pike pole this smaller version has a shorter handle that resembles one from a shovel. It is normally used to open up areas that are not generally visible to check for fire extension and gets its name from the fact that it can be used in small spaces.

CNS  

Pertaining to the central nervous system. See Central Nervous System.

CNS depressants

Compounds that have the predominant effect of depressing or blocking the activity of the central nervous system. The primary mental effects include the disruption of the ability to think, sedation, and lack of motivation.

CNS stimulants

Compounds that have the predominant effect of flooding the brain with too much information. The primary mental effect is loss of concentration, causing indecisiveness and the ability to act in a sustained, purposeful manner.

CO2

Carbon dioxide. A heavier than air gas used to extinguish Class B fires by smothering or by displacing the oxygen. A fire gas produced by the complete combustion of a carbonaceous material.

Cockloft 

A concealed space between the top floor and the roof of a structure.

Code

A set of rules and standards that have been adopted as mandatory regulations having the force and effect of law.

Code of Federal Regulations (CFR) 

The formal name given to those books or documents that contain the specific regulations provided for by law. A collection of the regulations established by law. Contact with the agency that issued the regulation is recommended for details and interpretation.

Coefficient of discharge

Correction factor relating to the shape of the hydrant discharge outlet; used when computing the flow from a hydrant. See C-Factor.

COG 

Continuity of Government

Cold air return

The ductwork (and related grills) that carries room air back to the furnace for re-heating.

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Cold zone

The area outside of the warm zone. Equipment and personnel are not expected to become contaminated in this area. This is the area where resources are assembled to support the hazardous materials operation. Those geographical areas designated as contamination-free from a chemical spill or release. This area contains the command post and other support functions necessary to control the incident. This is also referred to as clean (zone) or support (zone) in other documents.

Collar 

 Preformed flange placed over a vent pipe to seal the roofing above the vent pipe opening. Also called a vent sleeve.

Collar beam 

Nominal 1- or 2-inch-thick members connecting opposite roof rafters. They serve to stiffen the roof structure.

Column

A vertical structural compression member which supports loads.

Coma

A prolonged unconsciousness caused by disease, injury, or poison. A person in a state of coma cannot be roused, even by painful stimuli.

Combination apparatus 

A piece of fire apparatus designed to perform more than one function, usually called triple combinations, quads, or quints.

Combination ladders 

An A-frame or baby extension ladder.

Combination nozzle 

A nozzle designed to provide a straight stream and a fog stream. An all purpose nozzle.

Combustible

Capable of burning, generally in air under normal conditions of ambient temperature and pressure, unless otherwise specified. Combustion can occur in cases where an oxidizer other than the oxygen in air is present, e.g., chlorine, fluorine, or chemicals containing oxygen in their structure.

Combustible Gas Indicator (CGI)

An instrument that samples air and indicates whether there are combustible vapors present. Some units may indicate the percentage of the lower explosive limit of the air-gas mixture.

Combustible liquid

A liquid having a flash point at or above 100 degrees F. (37.8 degrees C). (see also Flammable Liquid.)

Combustible metal

Any metal that will burn.

Combustion

A rapid oxidation or chemical combination, usually accompanied by heat or light. A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow or flames. The production of light in the combustion process is the difference between oxidation and combustion: Oxidation, regardless of slowness, will give off heat but no light will be produced.

Combustion air

The duct work installed to bring fresh, outside air to the furnace and/or hot water heater. Normally 2 separate supplies of air are brought in: One high and One low.

Combustion chamber 

The part of a boiler, furnace or woodstove where the burn occurs; normally lined with firebrick or molded or sprayed insulation.

Combustion products

Heat, gases, solid particulates, and liquid aerosols produced by burning.

Command 

The act of directing and/or controlling resources by virtue of explicit legal, agency, or delegated authority. May also refer to the Incident Commander.

Command Post

The location of the officer in charge and support staff that make tactical decisions for the direction of the incident. Normal location for Public Information Officer and Liaison. See Incident Command Post

Command Staff

The Command Staff consists of the Incident Command and the special staff positions of  Public Information Officer, Safety Officer, and Liaison Officer and other positions as required. They report directly to the Incident Commander. They may have an Assistant or Assistants, as needed.

Commercial chassis 

Truck chassis produced by a commercial truck manufacturer. The chassis is in turn outfitted with a rescue or fire fighting body

Communication Unit 

An organizational Unit in the Logistics Section responsible for providing communication services at an incident or an EOC. A Communication Unit may also be a facility (e.g., a trailer or mobile van) used to provide support of an Incident Communications Center.

Communications Center

Location from which 9-1-1 calls are answered, all alarm signals are transmitted, all units are dispatched, and where records are kept of the movements of emergency units.

Compacts

Formal working agreements among agencies to obtain mutual aid

Company 

A basic fire fighting organizational unit consisting of firefighters and apparatus; headed by a sergeant, lieutenant, or captain. A manned fire engine is considered an engine company. Likewise, a compliment of manpower on a ladder truck is known as a ladder company.

Company log  

A record of the activities of a fire company, usually kept by a company officer.

Compartment 

A subdivision of a structure or design; a small chamber, receptacle, or container. A large container separated into smaller mutually isolated units. The space on an apparatus where firefighting and rescue equipment is stored.

Compatibility   

The matching of protective chemical clothing to the hazardous material involved to provide the best protection for the worker. The ability of two materials to be safely brought together during storage or spill.

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Compensation/Claims Unit 

Functional Unit within the Finance/Administration Section responsible for financial concerns resulting from property damage, injuries, or fatalities at the incident

Complement 

All firefighters assigned to a working unit, or the number of units assigned to a given alarm. Also the equipment assigned to a piece of apparatus.

Complex

Two or more individual incidents located in the same general area that are assigned to a single Incident Commander or to Unified Command

Compound gauge

A pressure gauge on fire department pumpers that records the pressure above and below atmospheric pressure. The pressure below atmospheric pressure is usually measured in inches (mm) of mercury and is called a vacuum. The pressure above atmospheric is measured in pounds per square inch or kilopascals; a term used to describe the gauge that measures the intake pressure on a fire pump.

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)

Known as CERCLA or SUPERFUND, it addresses hazardous substance releases into the environment and the cleanup of inactive hazardous waste sites. It also requires those who release hazardous substances, as defined by the Environmental Protection Agency (EPA), above certain levels (known as "reportable quantities") to notify the National Response Center.

Compressed gas

Any material or mixture having in the container absolute pressure exceeding 40 psi at 70 degrees F (21 degrees C), or having an absolute pressure exceeding 104 psi at 130 degrees F (54 degrees C). Also includes cryogenic or "refrigerated liquids" (DOT) with boiling points lower than -130 degrees at 1 atmosphere.

Compression web

A member of a truss system which connects the bottom and top chords and  which provides downward support.

Compressor 

A mechanical device that pressurizes a gas in order to turn it into a liquid, thereby allowing heat to be removed or added. A compressor is the main component of conventional heat pumps and air conditioners. In an air conditioning system, the compressor normally sits outside and has a large fan (to remove heat).

Computer Aided Management of Emergency Operations (CAMEO)

A computer database storage-retrieval system of preplanning data for on-scene use at hazardous materials incidents. A resource for making tactical decisions for air modeling during hazardous releases.

Concealed space

An area between walls or partitions, ceilings and roofs, floors and basement ceilings through which fire may spread undetected. Also soffits and other enclosed vertical or horizontal shafts through which fire may spread.

Concentration

The amount of a chemical agent present in a unit volume of air, usually expressed in milligrams per cubic meter (mg/m3.)

Concentration (corrosives)

In corrosives the amount of acid or base compared to the amount of water present. Corrosives have "strength" and "concentration." See Strength.

Concrete

The mixture of Portland cement, sand, gravel, and water. Used to make garage and basement floors, sidewalks, patios, foundation walls, etc. It is commonly reinforced with steel rods (rebar) or wire screening (mesh).

Concrete block

A hollow concrete 'brick' often 8" x 8" x 16" in size.

Concrete board 

A panel made out of concrete and fiberglass usually used as a tile backing material.

Condensation 

Going from the gaseous to the liquid state. Water vapor in the atmosphere caused to condense and release water by a reduction of temperature such as that following extinguishment of fire or from atmospheric temperature change that produces dew on vegetation and other hard surfaces. Beads or drops of water (and frequently frost in extremely cold weather) that accumulate on the inside of the exterior covering of a building. Use of louvers or attic ventilators will reduce moisture condensation in attics. A vapor barrier under the gypsum lath or dry wall on exposed walls will reduce condensation.

Condensation point 

That point where a gas or vapor changes into a liquid by cooling.

Condensing unit

The outdoor component of a cooling system. It includes a compressor and condensing coil designed to give off heat

Conduction

The transfer of heat from one body to another by direct contact (electric stove electrode to the utensil) within the same body (metal bar heated at one end), or through another heat-conducting medium (double boiler). Also means transmission of electrical current.

Conduit

Channels or pipes for carrying liquids long distances, such as an aqueduct. Tubes or underground passages for electric wires or cables.

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Confined space

A space that (1) is large enough and so configured that an employee can bodily enter and perform assigned work; (2) has limited or restricted means for entry or exit (e.g., tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry); and (3) is not designed for continuous employee occupancy. Has one or more of the following characteristics: 1) Contains or has the potential to contain a hazardous atmosphere. A hazardous atmosphere would be created by any of the following, including: a) Vapors exceed 10% of the lower flammable limit (LEL) b) Airborne combustible dust exceeds its LEL c) Atmospheric oxygen concentrations below 19.5% or above 23.5% d) Atmospheric concentration of any substance for which a dose or PEL is published and which could result in employee exposure in excess of these values e) Any other atmospheric condition which is immediately dangerous to life or health (IDLH) 2) Contains a material that has the potential for engulfing an entrant. 3) Has an internal configuration such that a person could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross section. 4) Contains any other recognized serious safety or health hazard.

Confinement  

Fire fighting operations required to prevent fire from extending to uninvolved areas or structures.

Conflagration    

A large, uncontrollable fire covering a considerable area and crossing natural fire barriers such as streets; usually involves buildings in more than one block and causes a large fire loss. Forest fires can also be considered conflagrations.

CONOPS 

Concept of Operations

Consequence management 

Measures to alleviate the damage, loss, hardship, or suffering caused by emergencies. It includes measures to restore essential government service, protect public health and safety, and provide emergency relief to affected governments, businesses, and individuals.

Constant pressure relay 

Method of establishing a relay water supply utilizing two or more pumpers to supply the attack pumper.

Construction drywall 

A type of construction in which the interior wall finish is applied in a dry condition, generally in the form of sheet materials or wood paneling as contrasted to plaster.

Construction, frame

A type of construction in which the structural components are wood or depend upon a wood frame for support.

Contagious

Capable of being transmitted from one person to another.

Contaminant

A pesticide or other toxic material found as a residue in or on a substance where it is not wanted. The attempt to prevent the spreading of contamination by holding it in, enclosing, encapsulating, or by controlling it. A toxic substance that is potentially harmful to people, animals, and the environment. A substance not in pure form.

Continuity tester  

A device that tells whether a circuit is capable of carrying electricity.

Control  

The overall program of fire confinement and suppression. A fire is under control when the fire advance has been halted.

Control center

A communications or dispatch center used by the fire service for emergency communications. There are also mobile command posts that can be taken directly to the fire scene and function as the incident operational control center.

Control joint 

Tooled, straight grooves made on concrete floors to "control" where the concrete should crack

Convection  

The transfer of heat by circulation currents in liquids and gases. See law of heat flow.

Convection column   

The rising column of heated air or gases above a continuing heat or fire source. Also known as thermal column.

Convulsion

An intense involuntary muscular contraction. 

Cooling

The reduction of heat by the quenching action or heat absorption of the extinguishing agent.

COOP 

Continuity of Operations Plan

Cooperating Agency

An agency supplying assistance other than direct operational or support functions or resources to the incident management effort

Coordination 

The process of systematically analyzing a situation, developing relevant information, and informing appropriate command authority of viable alternatives for selection of the most effective combination of available resources to meet specific objectives. The coordination process (which can be either intra- or interagency) does not involve dispatch actions. However, personnel responsible for coordination may perform command or dispatch functions within the limits established by specific agency delegations, procedures, legal authority, etc.

Coordination Center  

A facility that is used for the coordination of agency or jurisdictional resources in support of one or more incidents

Coped  

Removing the top and bottom flange of the end(s) of a metal I-beam. This is done to permit it to fit within, and bolted to, the web of another I-beam in a "T" arrangement

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Corbel  

The triangular, decorative and supporting member that holds a mantel or horizontal shelf.

 Core temperature

The temperature in the central part of the body. Rectal temperature is considered a measure of core temperature.

Corner boards

Used as trim for the external corners of a house or other frame structure against which the ends of the siding are finished.

Corner braces

Diagonal braces at the corners of the framed structure designed to stiffen and strengthen the wall.

Cornice

A concealed space near the eave of the building used for decoration. Overhang of a pitched roof , usually consisting of a fascia board, a soffit and appropriate trim moldings.

Corpus Delicti 

Evidence of substantial and fundamental facts necessary to prove the commission of a crime.

Corrosive

The ability to cause destruction of living tissue or many solid materials surfaces by chemical action. A chemical that causes visible destruction of or irreversible alterations in living tissue by chemical action at the site of contact; a liquid that causes a severe corrosion rate in steel. A corrosive is either an acid or a caustic (a material that reads at either end of the pH scale).

Cost Sharing Agreements 

Agreements between agencies or jurisdictions to share designated costs related to incidents. Cost sharing agreements are normally written but may also be oral between authorized agency or jurisdictional representatives at the incident.

Cost Unit  

Functional Unit within the Finance/Administration Section responsible for tracking costs, analyzing cost data, making cost estimates, and recommending cost-saving measures.

Counter flashing 

A metal flashing usually used on chimneys at the roofline to cover shingle flashing and used to prevent moisture entry.

Counterfort  

A foundation wall section that strengthens (and generally perpendicular to) a long section of foundation wall

Coupling   

The metal fitting device permanently attached to the end of water delivery equipment; used to connect two hose lines together, a pump or appliance devices as nozzles, appliances, discharge valves, or hydrants.

Course  

A row of shingles or roll roofing running the length of the roof. Parallel layers of building materials such as bricks, or siding laid up horizontally.

Cover

The practice of surrounding fire departments to “fill” units into depleted areas to provide emergency service; to cover exposures by placing primary fire streams in advantageous positions to protect buildings or rooms exposed to heat and fire; to protect with salvage cover.

CP

Command Post

CPE  

See Chemical Protective Equipment.

CPSC 

Consumer Product Safety Commission.

Crawl space

The area between ground and floor, ceiling and floor, or ceiling and roof, the dimensions of which are such that a person cannot stand up; often used for duct work, water pipes, and similar structural adjuncts.

Crew

See Single Resource

Cricket   

A second roof built on top of the primary roof to increase the slope of the roof or valley. A saddle-shaped, peaked construction connecting a sloping roof with a chimney. Designed to encourage water drainage away from the chimney joint.

Cripple

Short vertical 2 by 4's or 6's frame lumber installed above a window or door.

Crisis management 

Measures to resolve the hostile situation, investigate, and prepare a criminal case for persecution under Federal law.

Critique

An element of incident termination which examines the overall effectiveness of the emergency response effort and develops recommendations for improving the organization's emergency response system. This is intended to be a positive arena for constructive ideas, not critical towards pointing blame. This can occur at the command staff level down to the individual company level. It should include all parties and organizations that were involved in the incident.

Cross bridging 

Diagonal bracing between adjacent floor joists, placed near the center of the joist span to prevent joists from twisting.

Cross contamination

Contamination that takes place when a person or piece of equipment that has been exposed to a substance contaminates another which had no direct contact. Often referred to as secondary contamination.

Cross Tee   

Short metal "T" beam used in suspended ceiling systems to bridge the spaces between the main beams.

Crosslay

A method of storing pre-connected hose on a fire apparatus. It is called a crosslay due to the fact that the hose is stored perpendicular to, or across, the vehicle chassis as opposed to the hose in the hose bed which is parallel. Two different crosslays, set up so that they are easily deployed to one side of the engine or the other can be used as fast attack lines or lines for a back up crew. The system includes a swivel connection that allows unimpeded flow from the pump into the fire hose.

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Cross-trained

A person who has been given instruction in different tasks or skills: The department members have cross-trained in firefighting and emergency medical services.

Crowbar

A prying tool used in forcible entry to start or widen an opening, or pry a window or door.

Cryogenic

Substances having temperatures below -150 degrees F (-101.1 degrees C). Materials, which exist at extremely low temperatures, such as nitrogen. Those gases that must be cooled to a very low temperature in order to bring about a change from a gas to a liquid.

Curb

The short elevation of an exterior wall above the deck of a roof. Normally a 2 by 6 box (on the roof) on which a skylight is attached.

Curb stop

 Normally a cast iron pipe with a lid (@ 5" in diameter) that is placed vertically into the ground, situated near the water tap in the yard, and where a water cut-off valve to the home is located (underground). A long pole with a special end is inserted into the curb stop to turn off/on the water.

Cutaneous 

 Pertaining to the skin.

Cut-in brace

Nominal 2-inch-thick members, usually 2 by 4's, cut in between each stud diagonally.

CWA 

Chemical Warfare Agents

Cylinder

A container for liquids, gases, or solids under pressure. Ranges in size from aerosol containers found at home, such as spray deodorant, to the cryogenic (insulated) cylinders for nitrogen that can be approximately 24 inches in diameter and five feet high. All cylinders have a circular cross section with a valve arrangement at one end, and a majority will have a pressure relief device. Pressure ranges from a few pounds to several thousand pounds per square inch. Also, the self contained breathing apparatus bottle is known as an air cylinder,. These too can be pressurized to 6000 psi.