CT Fire Sprinkler key terms

A heat-activated device with a frangible element that opens at a set temperature and discharges water in a spray pattern over a defined floor area to control or extinguish a fire.

The nominal activation temperature marked on a sprinkler's link or bulb, selected to be above expected ambient ceiling temperatures so the device opens only in a real fire.

A glass vial filled with heat-sensitive liquid that shatters at its rated temperature, releasing the seal and allowing water to flow from the sprinkler.

A solder-type or bimetallic element that separates at a specified temperature to open a sprinkler, commonly used in older or special-service heads.

A discharge coefficient expressing sprinkler flow in gallons per minute divided by the square root of supply pressure in psi; larger values deliver more water at the same pressure.

The maximum permitted distance between sprinklers and between the last sprinkler and a wall, set by occupancy hazard and ceiling construction to ensure adequate coverage.

The maximum floor area a single sprinkler is permitted to protect, determined by hazard classification and the spacing rules of the applicable installation standard.

The minimum water application rate, usually in gallons per minute per square foot, that must be delivered over the design area for the occupancy hazard being protected.

The most hydraulically demanding remote floor area, defined by size and shape, over which water demand is calculated to size pipe and confirm supply adequacy.

A pressure-and-flow analysis of the piping network that sums friction loss, elevation change, and device losses to prove the water supply meets design demand.

Pressure lost as water moves through pipe, fittings, and valves, calculated from flow rate, pipe size, and equivalent length of the piping run.

The straight-pipe length that produces the same friction loss as a fitting or valve, added to actual pipe length in hydraulic calculations.

The pressure remaining at a reference point while water is flowing during a flow test, used with static pressure and flow to establish the available supply curve.

The pressure measured in a water supply system when no water is flowing, reflecting elevation head and the pressure maintained in the source main.

A field test that records static pressure, residual pressure, and flow rate at a hydrant or test valve so the available water supply can be plotted and evaluated.

The public main, private main, tank, or other source that delivers the pressure and flow a sprinkler system needs for its design demand.

A pump that boosts water pressure and flow from a supply source to meet sprinkler system demand, sized from the system's hydraulic calculation and supply curve.

The maximum pressure a fire pump produces at zero flow, which must be considered when setting relief valves and checking system component ratings.

The vertical section of sprinkler piping that connects the water supply main to the overhead distribution piping and typically carries the main control valve and alarm devices.

The primary feed pipe that supplies branch lines in a sprinkler system, running generally horizontally and sized to carry the total calculated flow.

The smaller pipe on which individual sprinklers are installed, fed by the cross main and sized according to the number of sprinklers it serves.

A short pipe section connecting the riser to a cross main or feed main, often fitted with a reducing fitting and used to align overhead piping.

A valve and pipe connection at the low point of the system used to drain water and to conduct a main drain test that reveals supply restrictions.

A test connection at the most remote part of the system that simulates a single sprinkler flowing, used to verify alarm activation and water flow.

A device or circuit that signals when water moves through the system piping, typically triggered by a flow switch or pressure switch on the riser.

A paddle device installed in the pipe that deflects with water movement and sends an alarm signal when sustained flow indicates a sprinkler has operated.

A check valve in a wet or dry pipe system that permits water into the system, prevents backflow, and initiates an alarm when water passes through.

A one-way valve that allows flow in a single direction, protecting the potable water supply from contamination and preventing reverse flow in sprinkler piping.

An assembly that stops reverse flow of nonpotable or stagnant water into the public supply, often required where a sprinkler system connects to a municipal main.

A sprinkler system with water held under pressure in the piping at all times, so an opened sprinkler discharges water immediately without any delay.

A system with pressurized air or nitrogen in the piping and water held back by a dry pipe valve, used where freezing temperatures would damage a wet system.

A special valve that holds back water with a clapper and air pressure differential, opening when a sprinkler releases air and system pressure drops.

The air pressure at which a dry pipe valve opens, set low enough to release quickly but high enough to avoid false trips from minor pressure changes.

Equipment that maintains air or nitrogen pressure in dry pipe and preaction system piping so the valve stays closed and the system stays ready.

A system that fills with water only after a detection signal, and in double-interlock designs also after a sprinkler opens, reducing accidental water discharge.

A system with open nozzles and a valve that opens on detection to discharge water from all heads at once, used for high-hazard or exposure protection.

A valve actuated by a detection system that admits water to open sprinklers or nozzles in a deluge system, often controlled by a solenoid or pilot line.

A device that opens to release excess pressure from the system, protecting piping and components from overpressure such as fire pump churn pressure.

The hydraulically most distant portion of the sprinkler system, where the design area is located and where pressure is lowest during a design flow.