NFPA Fire Code Information-Industry Glossary

Accessible Capable of being reached for inspection, maintenance, or removal without disturbing the permanent structure.

Accreditation Third-party attestation related to a conformity assessment body conveying formal demonstration of its competence to carry out specific conformity assessment tasks. These tasks include sampling and testing, inspection, certification, and registration.

A-Class Boundary A boundary designed to resist the passage of smoke and flame for 1 hour when tested in accordance with ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials, or UL 263, Standard for Fire Tests of Building Construction and Materials.

A-Class Division A fire barrier system consisting of bulkheads or decks and including all penetrations for piping and cables, doors, windows, and ductwork, providing 60 minutes of fire resistance when tested in accordance with established test methods.

Acoustic Emission Inspection A method of nondestructive testing (NDT) that utilizes acoustic or sound waves.

Active Fire Protection System A system that uses moving mechanical or electrical parts to achieve a fire protection goal.

Additive A liquid such as foam concentrates, emulsifiers, and hazardous vapor suppression liquids and foaming agents intended to be added to the water. A liquid such as foam concentrates, emulsifiers, and hazardous vapor suppression liquids and foaming agents intended to be added to the water.

Alarm A piece of equipment that generates a visual or audible signal that is intended to attract attention.

ANSI American National Standards Institute.   Antifreeze Sprinkler System A wet pipe system using automatic sprinklers that contains a liquid solution to prevent freezing of the system, intended to discharge the solution upon sprinkler operation.

ASME American Society of Mechanical Engineers.

ASTM American Society for Testing and Materials.

Automatic Fire Check A flame arrester equipped with a check valve to shut off the fuel gas supply automatically if a backfire occurs.

Automatic Fire Detection System A fire detection system that senses the presence of fire, smoke, or heat and activates a sprinkler system or an automatic alarm system.

Automatic Fire Detector A device designed to detect the presence of a fire signature and to initiate action. For the purpose of this Code, automatic fire detectors are classified as follows: Automatic Fire Extinguishing or Suppression System Operation Detector, Fire–Gas Detector, Heat Detector, Other Fire Detectors, Radiant Energy–Sensing Fire Detector, and Smoke Detector.

Automatic Sprinkler A fire suppression or control device that operates automatically when its heat-activated element is heated to its thermal rating or above, allowing water to discharge over a specified area.

Automatic Sprinkler System A sprinkler system of pipes with water under pressure that allows water to be discharged immediately when a sprinkler head operates.

Automatic Standpipe System A standpipe system that is attached to a water supply capable of supplying the system demand and that requires no action other than opening a hose valve to provide water at hose connections.

Automatic Wet Standpipe System A standpipe system containing water at all times that is attached to a water supply capable of supplying the system demand at all times and that requires no action other than opening a hose valve to provide water at hose connections.

Branch Lines The pipes supplying sprinklers, either directly or through sprigs, drops, return bends, or arm-overs.

Class A Fire A fire in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics.

Class B Fire A fire in flammable liquids, combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases.

Class C Fire A fire that involves energized electrical equipment where the electrical non-conductivity of the extinguishing media is of importance.

Class D Fire A fire in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium.

Class K Fires Class K fires are fires in cooking appliances that involve combustible cooking media (vegetable or animal oils and fats).

Clean Agent Electrically nonconductive, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.

Closed Piping System Interconnected piping that is designed to contain the flammable gas under pressure during normal operations and incorporates provisions for controlled release of contents.

Code A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards.

Compliance The condition of meeting or exceeding all applicable requirements of this standard.

Corrosion A condition exhibiting any signs of deterioration, including pitting or loss of metal.

Cross Main The pipes supplying the branch lines, either directly or through riser nipples.   Deluge Fire Sprinkler System A sprinkler system employing open sprinklers or nozzles that are attached to a piping system that is connected to a water supply through a valve that is opened by the operation of a detection system installed in the same areas as the sprinklers or the nozzles. When this valve opens, water flows into the piping system and discharges from all sprinklers or nozzles attached thereto.

Dry chemical fire suppression systems A means of applying dry chemical that can be automatically or manually activated to discharge through a distribution system onto or into the protected hazard. The system includes auxiliary equipment.

Dry-Pipe Fire Sprinkler System A sprinkler system employing automatic sprinklers that are attached to a piping system that contains air or nitrogen under pressure, the release of which (as from the opening of a sprinkler) permits the water pressure to open a valve known as a dry pipe valve, and the water then flows into the piping system and out the opened sprinkler.

Fire Suppression The activities involved in controlling and extinguishing fires.

Guided Wrap Wave Ultrasonic (GWWU) Guided wrap wave (or lamb wave) ultrasonic technology travels around the circumference of the pipe, revealing the conditions on the internal surface of the pipe.

Microbiologically Influenced Corrosion (MIC)  Microbiologically influenced corrosion (MIC) refers to the influence of microorganisms on the corrosion processes of metals and nonmetallic materials.

National Fire Protection Agency A trade association that provides fire, electrical, and life safety standards and codes for usage and adoption by local governments.

Non-Destructive Testing (NDT) National Fire Protection Agency

NFPA 25 National Fire Protection Agency

Nodules Build-up of organic or inorganic material on the interior surface of pipe wall that often presents as bumps or lumps that impede flow capacity within the system.

Obstruction Organic or inorganic material that partially or entirely obstructs or impedes the flow capicity through a system.

Obstruction Investigation A complete fire suppression system evaluation identifying deficiencies within the risers, cross mains, and branch lines.

Oxidation Reaction with oxygen either in the form of the element or in the form of one of its compounds.

Oxygen Corrosion Oxygen Corrosion is oxidation or rusting that occurs in a dry pipe fire sprinkler system when the air within the system contains oxygen and moisture.

Pin-Hole A penetration through the pipe wall often caused by pitting in the pipe wall interior beneath nodules or other corrosion build-up.

Pipe Circular conduit for conveying the extinguishing agent to the discharge nozzle(s). Wherever pipe is used in this standard, it is understood to also mean tube.

Piping Assemblies of piping components used to convey, distribute, mix, separate, discharge, meter, control, or snub fluid flows. Piping also includes pipe-supporting elements but does not include support structures such as building frames, bents, foundations, or any other equipment excluded from this standard.

Pitting The concentrated loss or degradation of the metal on the interior surface of the pipe wall resulting in pits or craters creating wall thinning.

Pre-Action/Preaction Fire Suppression A sprinkler system employing automatic sprinklers that are attached to a piping system that contains air that might or might not be under pressure, with a supplemental detection system installed in the same areas as the sprinklers.

Riser A pipe leading from the fire main to the fire station (hydrants) on upper deck levels.

Standing Water Water that is stationary or trapped in a pipe system resulting in corrosion and oxidation where the water is in contact with the wall of metal pipe systems.

Wall Thinning The loss or degradation of the metal on the interior surface of the pipe wall resulting in a thinner section of pipe wall that can lead to leaks from pinholes, cracks, rupture, or failure of the pipe wall.

Wet Pipe Sprinkler System A sprinkler system employing automatic sprinklers attached to a piping system containing water and connected to a water supply so that water discharges immediately from sprinklers opened by heat from a fire.