Chicago Fire Department Definitions

Ambulance Assist Run/Call - A call in which basic or advanced EMS care is rendered to an ill or injured person.

Apparatus - The name given to fire engines, fire trucks, paramedic ambulance and other motorized equipment.

Arson - The crime of maliciously (or perhaps recklessly) setting fire to property, especially a dwelling. Punishable in various degrees, depending upon the circumstances. 

Backdraft - A fire phenomenon caused when heat and heavy smoke (unburned fuel particles) accumulate inside a compartment, depleting the available air. Then, when oxygen/air is re-introduced, completing the fire triangle and causing rapid combustion. 

Bangor - This is a 50 foot, or larger, ladder that has "tormenter poles" to assist in the raising and to stabilize the sides. It is our largest stand-alone ladder.

Bank Down - What the smoke does as it fills a room, banks down to the floor, creating several layers of heat and smoke at different temperatures – the coolest being at the bottom. 

Battalion - A number of fire stations in a geographical area.  The city is divided into 24 Battalions.

Battalion Chief - The supervisor of the firehouses in the battalion and acts as incident commander for fires in his/her battalion.

BLEVE - Boiling Liquid Expanding Vapor Explosion.  Explosion of a pressure tank containing an overheated material when the vapor expansion rate exceeds the pressure relief capacity (e.g., steam boiler or propane tank). If the contents are flammable, the rapidly released vapor may react in a secondary fuel-air explosion. 

Box Alarm / Box Card - Developed from a card system which listed the companies that were due to respond on an alarm. This comes from the old practice of transmitting fire alarms through a telegraph system.

Bunkroom - A bedroom or sleeping area.

Candidate - A new firefighter on employment probation (a period of time during which his or her skills are improved, honed, tested, and evaluated). 

Captain - An officer responsible for their crew of firefighters as well the firehouse itself and all members on all shifts at their assigned firehouse.

Charged Line - Filling or using a fire hose line that is full of water.

Chicago Bar - A forcible entry tool created in Chicago to assist in forcing of doors, bars etc.

Cockloft - Structural space above the ceiling and below the rafters, often connecting adjacent occupancies and permitting fire to spread laterally, often unseen. 

Collapse Zone - Estimated as an area one and a half times the height of the fire building where a wall may fall. Fireground operations should not be conducted within the collapse zone.  Corners of the building are the safest place for operations.

Crew - The group of personnel consisting of an officer, firefighters or paramedics assigned to a fire apparatus or ambulance.

Crosslay - Arrangement of hose on an engine such that it can be quickly unloaded from either side of the apparatus; often pre-connected to a pump outlet and equipped with a suitable nozzle. 

Deck Gun - A large water nozzle attached to the top of the engine. Deck guns deliver larger amounts of water than hand-held hose.

Defensive Operations - This is a fire ground strategy based on firefighter safety and the protection of exposures. The goal is to simply confine the fire to the building/area of origin. No aggressive interior firefighting operations take place in the defensive mode, usually due to safety concerns for entering the building.

District - Geographical areas comprised of numerous battalions.  The city is divided into 5 districts, including the airports.

Drill - Training during which an emergency is simulated and the trainees go through the steps of responding as if it were real, or practicing particular skills to enhance a member’s ability to perform the skill during an emergency.

EMS - Emergency Medical Service. 

Engine - A motorized apparatus that has a pump, a 500-gallon water tank and hose. Often called a pumper.

Engineer - The member who drives the fire engine during routine driving and during emergencies. Also operates the pumps to deliver water through the fire hoses.

Evacuation - Removal of people from a dangerous area, in particular, a Hazmat incident, burning building, or other emergency. Also refers to act of removing firefighters from a structure in danger of collapsing. 

Exposure - Property near fire that may become involved by transfer of heat or burning material from main fire, typically by convection or radiation. May range from 40 feet to several miles, depending on size and type of fire or explosion. 

Extra Alarm - A request by an incident commander for additional personnel and apparatus.

Extrication - Removal of a trapped victim such as a vehicle extrication, confined space rescue, or trench rescue; sometimes using hydraulic spreader, Jaws of Life or other technical equipment.

Fire Academy - A location where candidates are trained as well as periodic training of the members of the department.

Fire Boat - A specialized watercraft and with pumps and nozzles designed for fighting shoreline and shipboard fires.

Fire Code - (Fire safety code) Regulations for fire prevention and safety involving flammables, explosives and other dangerous operations and occupancies. 

Fire Escape - A building structure arranged outside to assist in safe evacuation of occupants during an emergency; may connect horizontally beyond a fire wall or vertically to a roof or (preferably) to the ground, perhaps with a counter-weighted span to deny access to intruders.

Firefighter - The member who provides first aid to patients, uses the hose lines to deliver water to extinguish fires, makes hydrants, performs searches for victims and other physical work during an emergency. Also does the station cleaning and maintenance during daily station activities.

Fireground - The operational area at the scene of a fire; area in which incident commander is in control. Also used as name of radio frequency to be used by units operating in the fireground, as in “Responding units switch to fireground.” 

Firehouse - Another term for a fire station. Where fire apparatus is stored and where full-time firefighters work. 

Fire Inspector - A member of the Fire Prevention Bureau who is responsible for issuing permits and enforcing the fire code, including any necessary premises inspection, before allowing (or during) a large indoor gathering. 

Fire Insurance Patrol - Their mission was to respond to fire alarms along with the Chicago Fire Department and reduce the damage caused by smoke and water. They fought their way into burning buildings to save business records, other valuable items and cover property with their waterproof tarpaulins.  The Patrol was in service from 1871 – 1959.

Fire Load - The contents of the structure or residence during ordinary combustion of all the fuel in a given space.

Fire Marshal - Arson investigator.

Fire Pole - A pole installed between floors in fire stations, allowing firefighters responding to an alarm to quickly descend to the ground floor faster than by using a standard staircase.

Fire Wall - Building structure designed to delay horizontal spread of a fire from one area of a building to another, often regulated by fire code.

Flashover - Simultaneous ignition of combustible materials in a closed space, as when materials simultaneously reach their ignition temperature. 

Flashpoint - Lowest temperature at which a material will emit vapor combustible in air mixture. Lower than fire point of same material. 

Forcible entry - Gaining entry to an area using force to disable or bypass security devices, typically using force tools, sometimes using tools specialized for entry (e.g., Chicago Bar). 

Forward Lay - Procedure of stringing water supply hose from a water source toward a fire scene; co-pare with reverse lay. 

Friction Loss - Reduction of flow in a firehose caused by friction between the water and the lining of the hose. Depends primarily upon diameter, type and length of hose, and amount of water flowing through. 

Fully Involved - Term of size-up meaning the fire, heat and smoke in a structure are so widespread that internal access must wait until fire streams can be applied. 

Grease Fire - A fire involving any manner of cooking oil or other flammable cooking or lubricating materials. 

Hazmat - Hazardous materials, including solids, liquids, or gasses that may cause injury, death, or damage if released or triggered. 

High-rise Building - Any building taller than eighty feet. 

High-rise Pack - A shoulder load of hose with a nozzle and other tools necessary to connect the hose to a standpipe. 

Hose Tower - A tower in the firehouse that is used to dry the fire hose.

Hot Zone - Contaminated area of Hazmat incident that must be isolated; requires suitable protective equipment to enter and decontamination upon exit.

Hurst Tool - The copyrighted name of the hydraulic rescue tool, developed by Hurst, used to free people trapped in automobile crashes.

Incident Commander - The officer in charge of all activities at an incident.

Joker Stand - The communications center of an older Chicago firehouse which involved the telegraph key, speakers and phones.

Jumpseat - The rear facing seats, occupied most often by the firefighters, on a fire engine or truck company.

Knocked - Term used to indicate that the fire has been extinguished or the fires progress has been slowed.

Level I, II, III Incident -  A Hazmat term denoting the severity of the incident and the type of response that may be necessary, where Level III is the largest or most dangerous. 

Lieutenant - An officer responsible for a company of firefighters of one engine or truck.

Maltese Cross - The current emblem of the Chicago Fire Department that is based upon the cross worn on the tunics of the Knights Hospitallers of Jerusalem, AKA the "Knights of Malta".

Mass Casualty - Any incident that produces a large number of injured persons requiring emergency medical treatment and transportation to a medical facility. The exact number of patients that makes an incident "mass casualty" is defined by departmental procedures and may vary from area to area.

Master Stream - A large nozzle, either portable or fixed to a pumper, capable of throwing large amounts of water relatively long distances. 

Mutual Aid - An agreement between the Chicago Fire Department and nearby suburbs to assist each other during large scale emergencies by responding with available manpower and apparatus. 

OFI - The Office of Fire Investigation staffs Fire Marshals who investigates suspicious fires in the city of Chicago.

Overhauling - Conducted during the late stage in fire-suppression process during which the burned area is carefully examined for remaining sources of heat that may re-kindle the fire. Often coincides with salvage operations to prevent further loss to structure or its contents, as well as fire-cause determination and preservation of evidence.

Pike Pole - A piece of equipment used for overhaul. Most often it is use for the opening of ceilings. Of all the tools of the fire service, the pike pole is probably among the most often used.

Pompier Ladder - This is a ladder reportedly named for the firefighters of Paris, who are known as Pompiers.  This ladder has a large hook on one end. A firefighter would stick this in the window of the floor above, climb out the window and up the ladder, where he would repeat the process.  This is no longer used in the fire service.

Pre-planning - Fire protection strategy involving visits to potentially hazardous occupancies for inspection, follow up analysis and recommendations for actions to be taken in case of specific incidents. 

Progress Report - Reports that provide for an important exchange of information between Command and companies assigned to the incident.

Rack – Bed.

Rehab Area - The organized process of rehabilitating firefighters through re-hydration, active cooling, rest and medical assessment to ensure the safety, health and well-being of the exerted firefighter.

Reverse Lay - The process of stringing hose from a fire toward a source of water, i.e., a fire hydrant. 

RIT (Rapid Intervention Team) - Firefighters with specialized training, experience and tools, assigned to stand by for rescue of other firefighters inside a structure.

Salvage Cover - Heavy-duty tarpaulins folded or rolled for quick deployment to cover personal property subjected to possible water or other damage during firefighting. 

SCBA - A portable self contained breathing apparatus worn on the back of a firefighter that allows the users to breath fresh air contained in a pressurized cylinder through a face mask.

Search and Rescue - Entering a fire building or collapse zone for an orderly search for victims and removal of live victims. Becomes "recovery" if victims are not likely to be found alive. 

Sector - A physical or operational division of an incident.  A typical system for structure fires names the "front" of the building "sector 1", and continues clockwise around the building with sector 2 to the right of the building, 3 in the rear and 4 to the left. 

Shift - The work period of an assigned crew which is 24 hours 

Shops - The location in which the apparatus and tools are repaired.

Shut Off Pipe - A solid stream nozzle invented in Chicago which attaches to a 2 ½” hose line.  After the fire has been brought under control, it enables a 1 ¾” hose line to attach to it for washdown.

Siamese - A device used to combine two hose lines into one.

Size-up - Initial evaluation of an incident, in particular a determination of immediate hazards to responders, other lives and property, and what additional resources may be needed. Example: "Two-story brick taxpayer with heavy smoke showing from rear wooden porches and children reported trapped." 

Smoke-proof Stairwell - Building structure that isolates escape stairwells with relatively fireproof walls, self-closing doors, and positive pressure ventilation, to prevent smoke or fumes from entering the stairwell during evacuation of occupants during a fire or other emergency. 

Snorkel - Invented in Chicago, the snorkel is an articulating boom with a platform. It has the ability to spray water from the platform permanently plumbed into the system.

Solid Stream - Fire stream from round orifice of nozzle. Compare straight stream. 

Squad - A special operations apparatus that carries tools and equipment for heavy rescue.

Staging - Designated area in close proximity to an incident where responding resources arrive for assignment to another sector. The Incident Commander sets the Staging Area.

Straight Stream - Round, hollow stream formed as water passes a round baffle through a round orifice (e.g., on an adjustable nozzle.) Compare solid stream. 

Stripping Ladder - Created in Chicago and was designed to assist in opening roofs.

TIC (Thermal Imaging Camera) - This is a camera that can be used to seek out hidden fires, identify down victims or see through smoke.

Truck - A motorized apparatus that has a large mounted hydraulically raised  100-foot ladder. The truck also carries smaller ground ladders and varied equipment for specialized functions.

Turnouts or Bunkers - The set of protective pants and coat worn by firefighters to protect them from cuts, abrasions, heat and flames while fighting a fire or performing other duties.

Ventilation - Important procedure in firefighting in which the hot smoke and gases are removed from inside a structure, either by natural convection or forced, and either through existing openings or new ones provided by firefighters at appropriate locations (e.g., on the roof). Proper ventilation can save lives and improper ventilation can cause a backdraft or other hazards. 

Vertical Ventilation - Ventilation technique making use of the principle of convection in which heated gases naturally rise. 

Void Spaces - Enclosed portions of a building where fire can spread undetected. 

Working Fire - A confirmed fire in which companies will be leading out to extinguish and RIT companies are dispatched. 

Wye (Y) - A device for splitting one hose into two (usually smaller) lines.