Glossary of Fire Safety Terms
48Fire – Comprehensive Fire Protection Terms
ABC Fire Extinguisher
A multipurpose dry chemical fire extinguisher rated for Class A, B, and C fires. These extinguishers contain
monoammonium phosphate and are the most common type found in commercial buildings due to their
versatility in handling ordinary combustibles, flammable liquids, and electrical fires.
Related: Dry Chemical, Fire Classes, Multipurpose Extinguisher
Addressable Device
A fire alarm system component with a unique identification that allows the control panel to pinpoint its exact
location. Addressable devices provide specific information about which detector activated or which circuit has a
problem, enabling faster emergency response and easier troubleshooting compared to conventional systems.
Related: Fire Alarm System, Control Panel, Detector
Agent
The extinguishing substance contained within a fire extinguisher that suppresses or extinguishes fire. Common
agents include water, dry chemical, carbon dioxide, foam, and clean agents. Each agent is designed for specific
fire classes and has unique characteristics affecting its effectiveness and application.
AHJ (Authority Having Jurisdiction)
The organization, office, or individual responsible for enforcing fire codes and approving equipment and
procedures in a specific area. This typically includes fire marshals, building officials, or insurance inspectors
who have legal authority to ensure compliance with fire safety regulations.
Alarm System
A combination of initiating devices, control panels, and notification appliances designed to detect fire conditions
and alert building occupants. Fire alarm systems may include smoke detectors, heat detectors, manual pull
stations, horns, strobes, and voice evacuation systems.
Related: Fire Alarm System, Detector, Control Panel, Notification Appliance
Alarm Valve
A component in wet pipe sprinkler systems that opens to allow water flow when the system activates,
simultaneously triggering an alarm. The alarm valve prevents false alarms while ensuring reliable notification
when sprinklers discharge.Related: Sprinkler System, Wet Pipe System, Flow Switch
Annual Inspection
A comprehensive yearly examination of fire extinguishers required by NFPA 10. This inspection goes beyond
monthly checks and includes internal examination, pressure testing when necessary, weighing, and verification
of all mechanical parts. Annual inspections must be performed by certified technicians.
Related: NFPA 10, Maintenance, Certified Technician
ANSI
American National Standards Institute, an organization that oversees the development of voluntary consensus
standards for products, services, and systems in the United States. ANSI standards complement NFPA and
OSHA requirements in ensuring fire safety equipment meets performance and safety criteria.
Related: NFPA 10, OSHA, Standards, Listed
Antifreeze Sprinkler System
A wet pipe fire sprinkler system that contains antifreeze solution in the pipes to prevent freezing in unheated or
cold areas. When activated, the antifreeze mixture discharges along with water. Modern systems use listed
antifreeze solutions that meet NFPA 25 requirements.
Related: Wet Pipe System, Sprinkler System, NFPA 25
Automatic Sprinkler System
A fire suppression system with heat-activated sprinkler heads that automatically release water when
predetermined temperatures are reached. The system operates without human intervention, providing 24/7 fire
protection. Only sprinkler heads exposed to sufficient heat will activate, limiting water damage.
Related: Sprinkler Head, Wet Pipe System, Dry Pipe System
Backflow Preventer
A device installed in fire sprinkler system piping that prevents contaminated water from flowing back into the
potable water supply. Backflow preventers are required by plumbing codes and must be tested annually to
ensure proper operation and protect drinking water quality.
Related: Sprinkler System, Fire Pump, Water Supply
Battery Backup
Emergency power supply for fire alarm systems and emergency lighting that automatically activates when
primary power fails. Fire alarm systems typically require 24 hours of backup power, while emergency lighting
requires 90 minutes minimum. Batteries must be tested regularly and replaced according to manufacturer
specifications.
Related: Emergency Lighting, Fire Alarm System, Exit Sign
BC Fire Extinguisher
A fire extinguisher rated for Class B (flammable liquids) and Class C (electrical) fires. These typically contain
sodium bicarbonate or potassium bicarbonate dry chemical and are commonly found in areas with electrical
equipment or flammable liquid hazards.
Bracket
The mounting hardware used to secure a fire extinguisher to a wall or cabinet. NFPA 10 requires extinguishers
to be properly mounted with appropriate brackets to ensure accessibility and prevent damage. Extinguishers
must be mounted with the bottom at least 4 inches off the floor, and the top positioned according to weight: no
more than 5 feet high for units under 40 pounds, or no more than 3.5 feet high for units over 40 pounds.
Carbon Dioxide (CO2) Extinguisher
A fire extinguisher that uses carbon dioxide gas as the extinguishing agent. CO2 extinguishers are effective for
Class B and C fires and leave no residue, making them ideal for protecting sensitive electronic equipment. The
gas displaces oxygen and cools the fire but requires careful use in confined spaces.
Related: Clean Agent, Class B, Class C
Certified Fire Extinguisher Technician
A professional who has completed training and certification through recognized programs to inspect, maintain,
and recharge fire extinguishers. Certification ensures technicians understand NFPA standards, safety
procedures, and proper servicing techniques.
Class A Fire
Fires involving ordinary combustible materials such as wood, paper, cloth, rubber, and many plastics. These
fires leave ash and are typically extinguished by cooling with water or certain dry chemicals that coat the
material.
Class B Fire
Fires involving flammable liquids, gases, and greases including gasoline, oil, paint, propane, and cooking oils.
These fires require extinguishing agents that smother or interrupt the chemical reaction rather than cool with
water.
Class C Fire
Fires involving energized electrical equipment such as appliances, wiring, circuit breakers, and outlets. The “C”
classification indicates the extinguishing agent is non-conductive and safe to use on electrical fires. Once power
is disconnected, the fire becomes Class A or B.
Class D Fire
Fires involving combustible metals such as magnesium, titanium, sodium, and potassium. These specialized
fires require specific dry powder agents designed for the particular metal involved, as using standard
extinguishers can be dangerous or ineffective.
Class K Fire
FireFires involving cooking oils and fats typically found in commercial kitchens. Class K extinguishers use wet
chemical agents that create a foam blanket to cool the oil and prevent re-ignition. These have largely replaced
Class B extinguishers in kitchen environments.
Related: Wet Chemical, Commercial Kitchen, Suppression System
Clean Agent
Gaseous fire suppression agents that leave no residue after discharge. Examples include Halotron and
FM-200. These agents are ideal for protecting sensitive equipment, electronics, and valuable documents as
they extinguish fires without causing additional damage.
Combustion
The chemical process of burning involving oxidation that produces heat and light. For combustion to occur,
three elements must be present: fuel, oxygen, and heat, commonly referred to as the fire triangle. Fire
extinguishers work by removing one or more of these elements to stop the combustion process.
Related: Fire Triangle, Extinguishing Agent, Fire Classes
Compliance
Adherence to fire safety codes, standards, and regulations including NFPA, OSHA, and local fire codes.
Maintaining compliance requires proper equipment selection, installation, inspection, maintenance, and
documentation. Non-compliance can result in fines, insurance issues, and increased liability during fire
incidents.
Control Panel
The central component of a fire alarm system that monitors input devices (detectors, pull stations), processes
signals, and activates output devices (horns, strobes, sprinklers). Modern control panels provide specific
information about alarm locations, system status, and trouble conditions. Also called a Fire Alarm Control Panel
(FACP).
Related: Fire Alarm System, Addressable Device, Detector, Notification Appliance
Deluge System
A fire sprinkler system with open nozzles (no heat-activated elements) controlled by a deluge valve. When fire
detection systems activate the valve, water flows simultaneously through all open sprinkler heads in the
protected area.
Related: Sprinkler System, Dry Pipe System
Detector
A fire alarm device with sensors that respond to heat, smoke, or other fire indicators. Common types include
ionization smoke detectors, photoelectric smoke detectors, heat detectors, and combination units.
Related: Fire Alarm System, Smoke Detector
Discharge
The release of extinguishing agent from a fire extinguisher. After any discharge, even partial, an extinguisher
must be professionally serviced and recharged before being returned to service.
Dry Pipe System
A fire sprinkler system where pipes are filled with pressurized air or nitrogen instead of water. When a sprinkler
head activates, the air pressure drops, opening a dry pipe valve that allows water to flow.
Related: Sprinkler System, Wet Pipe System
Emergency Lighting
Backup lighting systems that automatically activate during power failures to illuminate exit routes and work
areas. Building codes require emergency lighting to provide adequate illumination for at least 90 minutes.
Related: Exit Sign, Battery Backup, Egress
Exit Sign
An illuminated sign marking emergency exits and egress routes. Exit signs must be visible from any point in the
building, continuously illuminated or equipped with emergency battery backup.
Related: Emergency Lighting, Egress
Fire Control
The process of limiting fire growth and preventing its spread, typically the goal when using portable fire
extinguishers. Fire control differs from fire suppression, which aims to completely extinguish the fire.
Related: Incipient Stage Fire, Portable Fire Extinguisher
Fire Pump
A dedicated pump that increases water pressure in fire sprinkler systems when municipal water supply pressure
is insufficient. Fire pumps automatically start when system pressure drops.
Related: Sprinkler System, NFPA 25
Fire Safety Training
Educational programs teaching employees and building occupants about fire prevention, emergency
procedures, and proper use of fire safety equipment. OSHA requires annual training for employees.
Related: OSHA, PASS Method
Flow Switch
A device installed in sprinkler system piping that detects water flow and sends a signal to the fire alarm control
panel.
Related: Sprinkler System, Fire Alarm System
FM-200
A clean agent fire suppressant used in gaseous fire suppression systems. FM-200 extinguishes fires primarily
by removing heat and leaves no residue, making it ideal for protecting electronics and data centers.
Related: Clean Agent, Halotron
Heat Detector
A fire alarm device that activates when air temperature reaches a predetermined level or rises rapidly. Heat
detectors are less prone to false alarms than smoke detectors.
Related: Fire Alarm System, Smoke Detector
Hydrostatic Test
A pressure test required at specific intervals to verify the structural integrity of fire extinguisher cylinders. The
test involves filling the cylinder with water and pressurizing it to check for leaks or weakness.
Related: NFPA 10
Incipient Stage Fire
The initial phase of a fire when flames are small, confined to the area of origin, and can potentially be controlled
with a portable fire extinguisher. This is the only stage when using a fire extinguisher is recommended.
Related: Fire Control, Portable Fire Extinguisher
Inspection
A regular examination of fire extinguishers to ensure they are accessible, fully charged, and operable. NFPA 10
requires monthly visual inspections and annual comprehensive inspections by certified technicians.
Ionization Smoke Detector
A smoke detection device using a small amount of radioactive material to ionize air between electrodes. When
smoke particles enter the chamber, they disrupt the electrical current, triggering an alarm.
Related: Smoke Detector, Fire Alarm System
Manual Pull Station
A manually operated device, typically mounted near building exits, that allows occupants to trigger the fire alarm
system when they discover a fire. Required in most commercial buildings per NFPA 72.
Related: Fire Alarm System, Control Panel
Monthly Inspection
A visual check performed every 30 days to verify that fire extinguishers are in their designated locations,
accessible, and appear ready for use.
Related: NFPA 10, Inspection
NFPA 10
The National Fire Protection Association Standard for Portable Fire Extinguishers. This comprehensive
standard establishes requirements for selection, installation, inspection, maintenance, and testing.
Related: Compliance, Inspection, Maintenance
NFPA 25
The National Fire Protection Association Standard for the Inspection, Testing, and Maintenance of
Water-Based Fire Protection Systems including sprinkler systems and fire pumps.
Related: Sprinkler System, Fire Pump
NFPA 72
The National Fire Protection Association National Fire Alarm and Signaling Code. Establishes requirements for
fire alarm system installation, testing, inspection, and maintenance.
Related: Fire Alarm System, Detector
Notification Appliance
Devices that alert building occupants to fire emergencies through audible signals (horns, bells) or visual signals
(strobes). Must meet specific requirements for sound levels and light intensity.
Related: Fire Alarm System, Life Safety
PASS Method
The recommended technique for operating a fire extinguisher: Pull the pin, Aim at the base of the fire, Squeeze
the handle, and Sweep from side to side.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
Photoelectric Detector
A smoke detection device using a light beam and photosensitive sensor. When smoke particles enter the
chamber, they scatter light onto the sensor, triggering an alarm.
Related: Smoke Detector, Fire Alarm System
Pre-Action System
A sophisticated sprinkler system requiring two separate events before water discharges: activation of detection
devices and opening of sprinkler heads. Ideal for protecting valuable equipment and documents.
Related: Sprinkler System, Dry Pipe System
Pressure
The force that propels extinguishing agent from the fire extinguisher. Stored pressure extinguishers maintain
constant pressure using nitrogen or compressed air.
Related: Gauge, Stored Pressure
Smoke Detector
A fire alarm device that senses smoke particles in the air. The two main types are ionization (best for
fast-flaming fires) and photoelectric (best for slow-smoldering fires).
Related: Fire Alarm System, Ionization Detector
Sprinkler Head
The discharge device in an automatic sprinkler system consisting of a heat-sensitive element, a deflector that
spreads water, and a threaded connection to the pipe.
Related: Sprinkler System, Automatic Sprinkler System
Sprinkler System
An integrated network of water pipes and sprinkler heads designed to detect and control fires automatically.
Types include wet pipe, dry pipe, pre-action, and deluge systems.
Related: Wet Pipe System, NFPA 25
Water Extinguisher
A fire extinguisher that uses water as its extinguishing agent, effective for Class A fires only. Water
extinguishers should never be used on electrical or flammable liquid fires.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
Wet Chemical
The extinguishing agent used in Class K fire extinguishers designed for commercial cooking equipment.
Typically potassium acetate solutions that create a foam layer.
Related: Class K, Commercial Kitchen
Wet Pipe System
The most common type of automatic sprinkler system where pipes are constantly filled with pressurized water.
Offers the fastest response time when a sprinkler head activates.
Related: Sprinkler System, Dry Pipe System, NFPA 25