Glossary

A

• After-flame means the time a test specimen continues to flame after the flame source has been removed.
• Aqueous film forming foam (AFFF) means a fluorinated surfactant with a foam stabilizer which is diluted with water to act as a temporary barrier to exclude air from mixing with the fuel vapor by developing an aqueous film on the fuel surface of some hydrocarbons which is capable of suppressing the generation of fuel vapors.
• Assembly Point. A designated safe area outside a building or facility where employees gather after an emergency evacuation. Assembly points are strategically located to ensure the safety of personnel and are crucial for conducting headcounts to confirm everyone has evacuated the building. They help emergency personnel quickly identify any missing persons and provide a centralized location for instructions or information from emergency coordinators. Assembly points should be clearly marked, easy to access, and at a safe distance from potential hazards.
• Auto-ignition Temperature. The lowest temperature at which a substance will spontaneously ignite without the presence of an ignition source. This property is critical for assessing fire risk during the storage and handling of chemicals. Substances with low auto-ignition temperatures may require special precautions to prevent accidental fires.
• Automatic fire detection device means a device designed to automatically detect the presence of fire by heat, flame, light, smoke or other products of combustion.
• Automatic Fire Suppression System. A system designed to automatically detect and control fires without requiring human intervention, minimizing fire damage and providing early response. Common types include sprinkler systems, gaseous suppression systems, and foam extinguishing systems. These systems are activated by fire indicators such as heat, smoke, or flames. They are essential in high-risk environments and help reduce fire spread, protecting both people and property. OSHA regulations may require such systems in specific types of buildings or facilities based on risk assessment.

B

• Buddy-breathing device means an accessory to self-contained breathing apparatus which permits a second person to share the same air supply as that of the wearer of the apparatus.

C

• Carbon dioxide means a colorless, odorless, electrically nonconductive inert gas (chemical formula CO2) that is a medium for extinguishing fires by reducing the concentration of oxygen or fuel vapor in the air to the point where conbustion is impossible.
• Class A fire means a fire involving ordinary combustible materials such as paper, wood, cloth, and some rubber and plastic materials.
• Class A Fire Extinguisher. A fire extinguisher designed to combat fires involving ordinary combustible materials such as wood, paper, cloth, and some plastics. These extinguishers use water, foam, or dry chemicals to cool the flames and reduce the heat needed to sustain combustion. OSHA standards require workplaces with potential Class A fire risks to have appropriate extinguishers readily available, and employees should be trained in their proper use.
• Class B fire means a fire involving flammable or combustible liquids, flammable gases, greases and similar materials, and some rubber and plastic materials.
• Class B Fire Extinguisher. This fire extinguisher is used to combat fires fueled by flammable or combustible liquids, such as gasoline, oil, and grease. Class B extinguishers work by smothering the fire and cutting off its oxygen supply, commonly using foam or carbon dioxide agents. OSHA mandates the availability of Class B extinguishers in workplaces where such materials are present, as well as training employees on when and how to use them effectively.
• Class C fire means a fire involving energized electrical equipment where safety to the employee requires the use of electrically nonconductive extinguishing media.
• Class C Fire Extinguisher. An extinguisher specifically for fires involving electrical equipment, such as computers, wiring, and appliances. These extinguishers use non-conductive agents like dry chemicals or carbon dioxide to extinguish flames without risking electrical shock. They are essential for workplaces with substantial electrical equipment, and OSHA requires proper placement and training for use.
• Class D fire means a fire involving combustible metals such as magnesium, titanium, zirconium, sodium, lithium and potassium.
• Cross braces mean the horizontal members of a shoring system installed perpendicular to the sides of the excavation, the ends of which bear against either uprights or wales.

D

• Dry chemical means an extinguishing agent composed of very small particles of chemicals such as, but not limited to, sodium bicarbonate, potassium bicarbonate, urea-based potassium bicarbonate, potassium chloride, or monoammonium phosphate supplemented by special treatment to provide resistance to packing and moisture absorption (caking) as well as to provide proper flow capabilities. Dry chemical does not include dry powders.
• Dry powder means a compound used to extinguish or control Class D fires.

E

• Education means the process of imparting knowledge or skill through systematic instruction. It does not require formal classroom instruction.
• Emergency Action Plan (EAP). An OSHA-required written document that outlines specific procedures for employees to follow in the event of an emergency. The EAP includes methods for reporting fires, evacuating safely, and accounting for employees. It designates roles and responsibilities, such as evacuation coordinators, and provides training requirements for personnel. This plan must be accessible to employees, regularly reviewed, and updated to ensure it addresses all potential workplace emergencies.
• Emergency Evacuation Drill. A simulated emergency procedure in which employees practice the actions outlined in the Emergency Action Plan, including the safe and orderly evacuation of the building. Drills ensure employees are familiar with escape routes, assembly points, and emergency roles. OSHA recommends regular evacuation drills to assess preparedness and improve response times, making sure personnel are ready for real-life emergencies.
• Emergency Notification System. A communication system that alerts employees, visitors, and emergency personnel about an emergency situation. These systems include audible alarms, public address systems, mobile alerts, and digital displays. They play a crucial role in providing immediate information during crises, reducing confusion, and guiding safe evacuation or sheltering actions.
• Enclosed structure means a structure with a roof or ceiling and at least two walls which may present fire hazards to employees, such as accumulations of smoke, toxic gases and heat, similar to those found in buildings.
• Evacuation Coordinator. An individual designated to oversee the evacuation process, ensuring that everyone follows the Emergency Action Plan during an emergency. This role typically involves organizing headcounts, assisting people with special needs, communicating with emergency services, and ensuring that all personnel have reached the assembly point. The coordinator may also conduct training and drills to maintain high evacuation standards.
• Exit Route. A continuous, unobstructed path that leads employees from any point inside a workplace to a safe area outside the building. OSHA requires multiple, well-marked exit routes that are accessible, properly lit, and free from obstructions. Exit routes should include doors, corridors, and any emergency exit signage needed to safely guide people out of the building during an emergency.
• Extinguisher classification means the letter classification given an extinguisher to designate the class or classes of fire on which an extinguisher will be effective.
• Extinguisher rating means the numerical rating given to an extinguisher which indicates the extinguishing potential of the unit based on standardized tests developed by Underwriters' Laboratories, Inc.

F

• Fire Alarm System. An automated system that detects fire-related incidents by sensing smoke, heat, or flames. The system activates a warning alarm, often connected to emergency lighting or sprinkler systems, to alert building occupants and facilitate a prompt evacuation. Fire alarm systems are a core requirement in many workplaces per OSHA and local fire codes, enabling early fire detection and response.
• Fire brigade (private fire department, industrial fire department) means an organized group of employees who are knowledgeable, trained, and skilled in at least basic fire fighting operations.
• Fire Extinguisher Training. OSHA-required training that instructs employees on the correct use of fire extinguishers, covering types of extinguishers, types of fires, and the proper technique for extinguishing fires. This training ensures that employees understand how to safely use extinguishers and can make quick, informed decisions if a fire starts.
• Fixed extinguishing system means a permanently installed system that either extinguishes or controls a fire at the location of the system.
• Fire Hazard Assessment. A comprehensive process to identify potential fire hazards within the workplace, including flammable materials, ignition sources, and risks posed by building layout. This assessment forms the basis of the fire prevention plan, as it enables the organization to address hazards before they lead to an incident. OSHA recommends regular assessments as part of maintaining a safe work environment.
• Fire Prevention Plan (FPP). A written document mandated by OSHA that outlines procedures to prevent fires. This includes identifying fire hazards, controlling ignition sources, regular cleaning of combustible waste, and proper storage practices for flammable materials. The FPP also assigns responsibility to employees and includes information on required fire prevention equipment and regular inspections to ensure compliance.
• Fire Watch. A designated person or team tasked with monitoring an area for potential fire hazards, especially during hot work (such as welding). The fire watch ensures that immediate actions can be taken if sparks or flames are detected, minimizing fire risks in high-risk activities. OSHA often requires a fire watch as part of a hot work permit.
• Flammable Materials Storage. OSHA-prescribed guidelines for the safe storage of flammable or combustible materials, typically requiring the use of flame-resistant cabinets or designated storage rooms. Proper storage reduces the risk of accidental ignition and minimizes fire hazards. Regular inspections and inventory controls are part of effective flammable materials management.
• Flame resistance is the property of materials, or combinations of component materials, to retard ignition and restrict the spread of flame.
• Foam means a stable aggregation of small bubbles which flow freely over a burning liquid surface and form a coherent blanket which seals combustible vapors and thereby extinguishes the fire.

G

• Gaseous agent is a fire extinguishing agent which is in the gaseous state at normal room temperature and pressure. It has low viscosity, can expand or contract with changes in pressure and temperature, and has the ability to diffuse readily and to distribute itself uniformly throughout an enclosure.

H

• Halon 1211 means a colorless, faintly sweet smelling, electrically nonconductive liquefied gas (chemical formula CBrC1F2) which is a medium for extinguishing fires by inhibiting the chemical chain reaction of fuel and oxygen. It is also known as bromochlorodifluoromethane.
• Halon 1301 means a colorless, odorless, electrically nonconductive gas (chemical formula CBrF3) which is a medium for extinguishing fires by inhibiting the chemical chain reaction of fuel and oxygen. It is also known as bromotrifluoromethane.
• Hazardous Materials (HazMat). Substances that pose risks to health, safety, or property if not handled and stored properly, such as chemicals, gases, and flammable liquids. OSHA requires emergency action and fire protection plans to include specific protocols for managing hazardous materials, such as proper storage, labeling, and emergency response procedures.
• Helmet is a head protective device consisting of a rigid shell, energy absorption system, and chin strap intended to be worn to provide protection for the head or portions thereof, against impact, flying or falling objects, electric shock, penetration, heat and flame.
• Hot Work Permit. A document that authorizes work involving open flames, sparks, or heat, such as welding or soldering. A hot work permit specifies safety measures required to prevent fires, such as keeping fire extinguishers nearby and designating a fire watch. Permits are typically required by OSHA to ensure fire risks are minimized during high-heat activities.

I

• Ignition Source Control. Measures to eliminate or control sources of ignition, such as open flames, electrical sparks, or hot surfaces, that could ignite flammable materials. Control methods include grounding equipment, using spark-resistant tools, and ensuring a smoke-free environment near flammable substances. OSHA recommends regular inspections to identify and control potential ignition sources.
• Incident Command System (ICS). A standardized emergency response structure that designates specific roles and responsibilities for coordinating efforts, resources, and communications during an emergency. ICS is used for managing a wide range of emergencies, from fires to natural disasters, and is especially useful in large organizations with complex emergency response needs.
• Incipient stage fire means a fire which is in the initial or beginning stage and which can be controlled or extinguished by portable fire extinguishers, Class II standpipe or small hose systems without the need for protective clothing or breathing apparatus.
• Inspection means a visual check of fire protection systems and equipment to ensure that they are in place, charged, and ready for use in the event of a fire.
• Interior structural fire fighting means the physical activity of fire suppression, rescue or both, inside of buildings or enclosed structures which are involved in a fire situation beyond the incipient stage.

J

• Job Hazard Analysis (JHA). A safety management process that involves a thorough examination of individual job tasks to identify potential hazards and outline control measures for performing these tasks safely. JHA is particularly critical in environments where employees may be exposed to fire hazards, hazardous chemicals, or complex machinery. In the context of fire protection and emergency action plans, JHA identifies specific job-related risks (e.g., tasks involving open flames or combustible materials) and helps create safe work procedures. This can include requiring personal protective equipment (PPE), developing specific emergency response procedures, or implementing engineering controls to reduce fire risk. JHA is an integral part of OSHA compliance and proactive risk management.

K

• Knockdown. In firefighting and fire response terminology, "knockdown" refers to the initial suppression or containment of a fire to reduce its intensity and prevent it from spreading. Firefighters and safety personnel aim to knock down flames quickly using extinguishers, hoses, or sprinkler systems, which can give time to evacuate occupants, contain the blaze, and allow for safer access to the area. This stage is essential in fire response as it helps control fire damage and improves the safety of emergency responders. For workplaces, having the appropriate knockdown equipment (like fire extinguishers or sprinkler systems) readily accessible can help employees respond to smaller fires before they escalate.

L

• Lining means a material permanently attached to the inside of the outer shell of a garment for the purpose of thermal protection and padding.
• Local application system means a fixed fire suppression system which has a supply of extinguishing agent, with nozzles arranged to automatically discharge extinguishing agent directly on the burning material to extinguish or control a fire.
• Lockout/Tagout (LOTO). OSHA-required safety procedures to control hazardous energy when working with machinery and equipment. LOTO prevents accidental machine activation by requiring equipment to be "locked" and "tagged" with warning labels. This protects workers from potential hazards, including those that could lead to fire or other emergencies.

M

• Maintenance means the performance of services on fire protection equipment and systems to assure that they will perform as expected in the event of a fire. Maintenance differs from inspection in that maintenance requires the checking of internal fittings, devices and agent supplies.
• Means of Egress. A continuous and unobstructed path of exit from any point within a workplace, leading to a safe area outside. OSHA requires clearly marked and accessible egress routes in all facilities. Means of egress are vital for safe evacuation and should be regularly inspected for compliance.
• Multipurpose dry chemical means a dry chemical which is approved for use on Class A, Class B and Class C fires.

N

• National Fire Protection Association (NFPA). The NFPA is a globally recognized organization that develops standards, codes, and guidelines aimed at minimizing the risk and impact of fire and other hazards. NFPA’s standards cover a broad range of safety issues, including fire protection, electrical safety, and emergency response planning. Important standards from NFPA that OSHA references include NFPA 101 (Life Safety Code), which provides guidelines for fire prevention and safe evacuation, and NFPA 70 (National Electrical Code), which sets electrical safety standards. Compliance with NFPA standards often forms the foundation of an OSHA-compliant fire protection and emergency action plan, helping workplaces prevent fire hazards, maintain safe facilities, and effectively respond to emergencies.

O

• Outer shell is the exterior layer of material on the fire coat and protective trousers which forms the outermost barrier between the fire fighter and the environment. It is attached to the vapor barrier and liner and is usually constructed with a storm flap, suitable closures, and pockets.

P

• Personal Protective Equipment (PPE). Clothing and gear designed to protect employees from health and safety hazards. For fire risks, PPE can include flame-resistant clothing, gloves, respirators, and eye protection. OSHA mandates the use of PPE for employees exposed to high-risk areas, ensuring greater safety during emergency responses.
• Portable Fire Extinguishers. Handheld devices designed to extinguish small, incipient fires. OSHA requires portable extinguishers in workplaces, with specified maintenance, inspection, and accessibility standards. Training in proper use is also required, as portable extinguishers are the first line of defense in many emergency fire situations.
• Positive-pressure breathing apparatus means self-contained breathing apparatus in which the pressure in the breathing zone is positive in relation to the immediate environment during inhalation and exhalation.
• Pre-discharge employee alarm means an alarm which will sound at a set time prior to actual discharge of an extinguishing system so that employees may evacuate the discharge area prior to system discharge.

Q

• Quick disconnect valve means a device which starts the flow of air by inserting of the hose (which leads from the facepiece) into the regulator of self-contained breathing apparatus, and stops the flow of air by disconnection of the hose from the regulator.

R

• Sprinkler alarm means an approved device installed so that any waterflow from a sprinkler system equal to or greater than that from single automatic sprinkler will result in an audible alarm signal on the premises.
• Sprinkler system means a system of piping designed in accordance with fire protection engineering standards and installed to control or extinguish fires. The system includes an adequate and reliable water supply, and a network of specially sized piping and sprinklers which are interconnected. The system also includes a control valve and a device for actuating an alarm when the system is in operation.
• Standpipe system - Class I means a 2½″ (6.3 cm) hose connection for use by fire departments and those trained in handling heavy fire streams.
• Standpipe system - Class II means a 1½″ (3.8 cm) hose system which provides a means for the control or extinguishment of incipient stage fires.
• Standpipe system - Class III means combined system of hose which is for the use of employees trained in the use of hose operations and which is capable of furnishing effective water discharge during the more advanced stages of fire (beyond the incipient stage) in the interior of workplaces. Hose outlets are available for both 1½″ (3.8 cm) and 2½″ (6.3 cm) hose.
• Small hose system means a system of hose ranging in diameter from ⅝″ (1.6 cm up to 1½″ (3.8 cm) which is for the use of employees and which provides a means for the control and extinguishment of incipient stage fires.

S

• Shelter-in-Place. A protocol where employees remain in a designated safe area indoors rather than evacuate. This may be necessary in chemical spills, severe weather, or hazardous air conditions, where going outside could increase risks. The shelter-in-place location is often well-ventilated, stocked with supplies, and monitored for environmental changes.
• Smoke Alarms. Fire detection devices that identify smoke and trigger an audible alarm to alert building occupants. Smoke alarms are essential in providing early warning, allowing people to evacuate safely before the fire spreads. OSHA requires smoke alarms in various settings, depending on the type of facility and associated fire risks.
• Sprinkler System. An automated fire suppression system using water to control or extinguish fires. Sprinklers are heat-activated, releasing water in response to a specific temperature. They are essential for reducing fire spread and are required in many commercial and industrial facilities under OSHA and fire code regulations.

T

• Total flooding system means a fixed suppression system which is arranged to automatically discharge a predetermined concentration of agent into an enclosed space for the purpose of fire extinguishment or control.
• Training means the process of making proficient through instruction and hands-on practice in the operation of equipment, including respiratory protection equipment, that is expected to be used and in the performance of assigned duties.
• Training Requirements. OSHA's requirements for training employees on emergency and fire response plans, including the use of fire extinguishers, evacuation procedures, and general emergency protocol. Training ensures employees understand how to respond promptly and safely during an emergency, reducing risk and injury.
• Two-Way Communication System. A system enabling real-time communication between employees and emergency personnel, essential for coordinated responses. Systems can include radios, intercoms, and mobile apps, helping to relay critical updates and instructions during an emergency.

U

• Utility Control. Utility control refers to the procedures and actions taken to manage building utilities, such as gas, electricity, and water, during an emergency to prevent secondary hazards. In a fire emergency, shutting off gas lines can prevent explosions, while deactivating electrical systems reduces the risk of electrical shock or secondary fires. Utility control is part of the emergency action plan, and designated personnel, often trained as part of their OSHA safety compliance, are responsible for safely shutting down utilities. Proper utility control procedures are vital for protecting both employees and emergency responders from added risks during fire response efforts.

V

• Vapor barrier means that material used to prevent or substantially inhibit the transfer of water, corrosive liquids and steam or other hot vapors from the outside of a garment to the wearer's body.

X

• Xerophyte Fire Hazards. Xerophytes, or drought-resistant plants, are often found in arid climates and are adapted to survive with minimal water. However, in dry or hot conditions, these plants, like cacti or certain shrubs, can become highly flammable. In workplaces with xerophyte landscaping, especially in regions prone to wildfires, fire protection plans may include xerophyte management strategies to reduce fire risks. This can involve maintaining moisture levels, pruning dried vegetation, and creating defensible spaces around facilities. Xerophyte fire hazard management is particularly relevant to outdoor workplaces, construction sites, and facilities with large landscaped areas, helping to prevent fires from spreading to building structures.

Y

• Yield Control Zones. Yield control zones are designated areas within a facility where employees or equipment operators must reduce speed, yield to other personnel, or exercise caution to maintain safe passage, especially near emergency exits or evacuation routes. Yield control zones help prevent congestion and ensure that pathways remain unobstructed during emergencies, facilitating safe and quick evacuations. In facilities with heavy equipment or high foot traffic, these zones help minimize collisions or delays during an emergency, such as a fire or chemical spill. Yield control zones are marked with signage and floor markings as part of the emergency action plan to support orderly and efficient evacuation.

Z

• Zone Isolation. A strategy in fire protection that divides a facility into sections with barriers, such as fire doors, to prevent the spread of fire. Zone isolation protects life and property by containing the fire to a smaller area and allowing more time for evacuation and fire response. This strategy is often required in high-occupancy buildings to control fire risks.
• Zone of Refuge. A designated safe area within a building where occupants can shelter temporarily if evacuation is not possible or safe. Zones of refuge are often located in stairwells, areas protected by fire-rated doors and walls, or designated rooms with access to emergency communication systems. These areas are essential in high-rise buildings, healthcare facilities, or workplaces where immediate evacuation may be challenging, providing a protected space for occupants to await rescue. OSHA and local fire codes may require zones of refuge in large buildings, particularly for individuals with mobility impairments. Refuge zones are critical for enhancing fire and emergency safety, ensuring that individuals have secure locations to wait for further assistance or until conditions improve.