NICET Special Hazards Level I key terms

An electrically nonconductive extinguishing agent that evaporates cleanly and leaves no residue, used to protect occupied spaces and sensitive equipment. It works mainly by absorbing heat and interrupting the combustion chemistry.

A clean extinguishing agent built from carbon and halogen atoms, such as an HFC or FK-5-1-12. It extinguishes mainly by absorbing heat and disrupting the flame chemistry, and it is stored as a liquid.

A clean agent made from naturally occurring gases, usually nitrogen, argon, or a blend, that extinguishes by lowering the oxygen concentration below the level that supports combustion. It is stored as a compressed gas.

The agent concentration selected for a hazard, set above the minimum extinguishing concentration with a safety margin and kept below the limit safe for people. It is the basis for calculating the agent quantity.

The lowest agent concentration accepted for a specific fuel, found by adding a required safety factor to the cup burner extinguishing value. Calculations must not fall below it for the hazard being protected.

The agent concentration, measured in a standardized small-scale test, that just extinguishes a liquid fuel flame. It is the reference point from which minimum design concentrations are derived for clean agents.

The highest agent concentration at which testing showed no adverse physiological effect on people. It sets the ceiling for designs in normally occupied spaces and is reported with a corresponding exposure time.

A flammable or combustible liquid or gas hazard, such as a solvent bath or fuel spill. Clean agent and foam designs for these fuels depend on the specific material and its flash point.

An electrical or electronic fire risk, such as energized equipment or a control cabinet. The classification matters because the extinguishing agent must be electrically nonconductive and leave no conductive residue.

A system that discharges agent into an enclosed volume to build and hold an extinguishing concentration throughout the space. The enclosure must be able to retain the agent for the required holding time.

A system that applies agent directly onto a specific hazard rather than filling the whole room. It suits open or unenclosable equipment and is designed around the hazard's footprint and discharge rate.

A door fan or pressurization test that measures leakage of the protected room to confirm it can hold the agent concentration for the required time. Failed results require sealing before acceptance.

The period during which a total flooding system must maintain the design concentration after discharge, allowing occupants to evacuate and responders to act. It is verified by the enclosure integrity test.

The time allowed for occupants to leave a space before or during agent discharge, set by the design and by alarm and door hardware arrangements. It is tied to the physiological limits of the agent used.

An alarm that sounds before agent is released, warning occupants to evacuate and giving them time to leave. Its duration and audibility are set by the design and by the occupancy of the space.

A programmed pause between the alarm or detection signal and the actual agent release. It provides time for evacuation and for personnel to abort a discharge when the hazard is minor.

A manually operated device that stops or postpones the automatic discharge sequence, usually during the delay period. It is intended for trained personnel who can confirm the alarm is unwanted.

A pull station or button that lets a person start agent discharge by hand, independent of automatic detection. It is located at the exit and marked for the hazard it controls.

The wiring and devices, such as smoke or heat detectors, that sense a fire condition and signal the control panel. Cross-zoning or two-detector logic is often used to reduce false discharges.

A detection arrangement requiring signals from two independent zones before discharge, reducing the chance of a false release. One zone alone may sound an alarm but will not trip the agent.

The unit that monitors detection circuits, manages alarms, delays, and abort signals, and energizes the release circuit. It also supervises the system for trouble conditions and records events.

The supervised wiring and output that fires the actuation device, such as a solenoid or gas cartridge, to open the agent container valve. It is energized only when the discharge sequence is confirmed.

The electrically or mechanically operated component that opens the container valve on command, such as a solenoid, squib, or gas cartridge. It is the final link between the control panel and the agent supply.

The valve on the agent cylinder that retains the charge and opens to release agent when actuated. It includes safety features such as a rupture disc and a pressure gauge connection.

The pipe network that carries agent from the container to the nozzles in the protected space. Its size and layout are engineered to deliver the agent within the required time and pattern.

A device that distributes agent into the protected space at a designed rate and pattern. Nozzle type, spacing, and elevation are chosen to achieve uniform concentration and avoid obstructions.

The hydraulic analysis that predicts agent flow, pressure, and discharge time through the piping and nozzles. It confirms the design will deliver the required concentration within the specified time.

The mass or volume of extinguishing agent required for the hazard, calculated from the protected volume, design concentration, and expected leakage. It accounts for temperature and altitude corrections.

A concentrated liquid that, when mixed with water and air, produces foam for suppressing flammable liquid fires. Its type and percentage determine the proportioning and application rates used.

Aqueous film-forming foam, a synthetic concentrate that spreads a thin film over liquid fuel surfaces to seal in vapors and cool the fuel. It is used for hydrocarbon spill and tank hazards.

A fuel such as alcohol or ketone that breaks down ordinary foam, requiring an alcohol-resistant concentrate. Designers must match the foam type to the fuel to prevent rapid foam breakdown.

The process of mixing foam concentrate with water at the correct percentage before it reaches the discharge device. It can be done with an eductor, a balanced pressure pump, or a bladder tank.

The ratio of finished foam volume to the volume of the foam solution used to make it. It distinguishes low, medium, and high expansion foams and guides which application method is suitable.

The foam maker, nozzle, or monitor that turns the foam solution into finished foam and directs it onto the hazard. Its type and placement control the reach and coverage of the foam blanket.

A special hazard system that discharges fine water droplets to cool the fire, displace oxygen near the flame, and wet surfaces. Small droplet size reduces water damage and electrical conductivity concerns.

A pre-engineered system that protects cooking appliances, hoods, and ducts with wet chemical or other listed agent. It interlocks with fuel shutoff and often with the building fire alarm.

A valve or control that stops the supply of gas or liquid fuel to protected cooking or process equipment when the suppression system actuates. It prevents continued fuel feed to the fire.

A packaged suppression system whose design, pipe sizes, and nozzle placement are fixed by the manufacturer's listing and cannot be field-modified outside those limits. It requires limited site-specific calculation.

Formal recognition by a nationally recognized testing laboratory that a product meets a published standard. Listed components must be installed within the limits of their listing to remain acceptable.

Acceptance of equipment or a design by the authority having jurisdiction, often after review of listings and plans. It is the formal permission to install or occupy the protected space.

The official or agency responsible for enforcing the code and approving installations, plans, and tests. Their interpretations can set local requirements beyond the published standard.

The documented test performed after installation to confirm the system operates as designed, including alarms, delays, and release logic. It is witnessed and recorded before the system is placed in service.