AZ Fire Sprinkler key terms

The amount of water, expressed in gallons per minute, that must be sprayed over each square foot of a protected floor area. It sets the starting point for sizing sprinkler discharge.

The hydraulically most demanding section of sprinkler piping, usually the area farthest from the supply or highest in elevation. Calculations begin at the sprinklers in this area.

A step-by-step pressure-loss analysis that proves a piping layout can deliver the required density and duration at the most remote sprinklers. It accounts for friction, elevation, and device losses.

A number describing how freely a sprinkler orifice passes water. Flow equals K times the square root of pressure, so a larger K yields more flow at the same pressure.

The standard friction-loss equation used in sprinkler hydraulics. It relates pipe diameter, flow rate, and a roughness coefficient to pressure lost per foot of pipe.

The straight-pipe length that would create the same friction loss as a fitting or valve. Adding these allowances converts a real layout into a simpler friction calculation.

Extra pressure or flow deliberately left unused in a hydraulic design so the system still works after supply fluctuations, pipe aging, or minor field changes. It is often a set percentage of demand.

A sprinkler listed for dwelling units, designed to control fires and improve survival odds rather than protect the building structure. It operates at lower flows and longer durations than standard sprinklers.

The traditional design approach in which a chosen density is applied over a specified operating area, with the area size depending on hazard classification and ceiling height.

The grouping of occupancies by fire severity, such as light, ordinary, or extra hazard. The class drives density, sprinkler spacing, and water duration requirements.

The maximum permitted distance between sprinklers and between branch lines. It depends on hazard class, ceiling construction, and the listing of the sprinkler used.

The floor area assigned to one sprinkler, found by multiplying spacing along the branch line by spacing between branch lines. It is capped by code based on hazard.

The required clearance between the sprinkler deflector and the ceiling or roof above it. Correct distance lets the spray pattern develop properly before hitting the surface.

The smaller pipe that carries sprinklers and connects to a cross main. Branch line size and the number of sprinklers on it affect friction and balance.

The pipe feeding branch lines in a tree or loop layout. It is larger than branch lines and is sized to carry the combined flow of all sprinklers it serves.

The vertical supply pipe that connects the underground water main to the overhead sprinkler piping. It typically carries the main control valve, check valve, and alarm devices.

The trim plate that covers the gap between a sprinkler or pipe and the finished wall or ceiling. It improves appearance and, when listed, helps maintain the intended spray pattern.

A graph of available pressure versus flow at the point of connection. Overlaying the system demand curve on it shows whether the supply can meet the design with margin to spare.

The water pressure measured when no water is flowing. It shows the resting pressure in the supply but says nothing about how much pressure remains once demand begins.

The pressure remaining at a test hydrant or gauge while water is flowing. Comparing it with static pressure reveals the friction loss and capacity of the supply.

A field measurement of static and residual pressure at known flow rates, used to build the water supply curve. Results must reflect actual conditions at the site.

An assembly that stops contaminated water from reversing into the public supply. Its type depends on the degree of hazard, and its friction loss must be included in calculations.

A backflow device with two check valves and a relief valve between them. It protects against high-hazard conditions and discharges water if either check fails.

A backflow preventer made of two independent check valves in series. It is used for lower-hazard connections where a single failure is unlikely to cause contamination.

A one-way valve at the riser that holds water in the overhead piping and prevents it from draining back into the supply. It also keeps alarm pressure stable.

A device that senses water movement in the piping and sends an alarm signal. It is common on wet systems and must be installed in a location with reliable flow.

The state agency that licenses contractors, administers trade classifications, and investigates complaints. It enforces workmanship standards and can suspend or revoke a license.

The individual who passes the trade and business exams and whose knowledge supports a contractor's license. That person must remain actively involved in the business.

A category that defines the scope of work a licensed contractor may legally perform, such as residential, commercial, or specialty fire protection work. Bidding outside it violates state law.

A guarantee submitted with a proposal that the bidder will enter the contract and furnish required bonds if selected. It protects the owner from a withdrawn or failed award.

A surety instrument that backs the contractor's promise to complete the work per the contract. If the contractor defaults, the surety steps in to finish or pay.

A surety guarantee that suppliers and subcontractors will be paid for labor and materials on the project. It shields the owner from mechanics' liens.

A percentage of each progress payment withheld by the owner until the work is accepted. It provides leverage for completion and must be tracked carefully in cash-flow planning.

A written modification to the contract scope, price, or schedule signed by the parties. Without one, extra work is hard to collect and may be disputed.

A compiled record of incomplete or defective items found near the end of a project. Closing it out is usually a condition of final payment and acceptance.

The authority's examination of submitted drawings and calculations for code compliance before permits are issued. Comments must be resolved before construction can proceed.

The last field verification that installed work matches approved plans and code, including alarms, valves, and signage. Passing it allows the system to be placed in service.

A pressure test of piping performed with water at a specified pressure for a set duration to reveal leaks. It is normally witnessed before piping is concealed.

A safety procedure that isolates energy sources and marks them so equipment cannot be started during service. It prevents injuries from unexpected energization or stored pressure release.

A pre-task review that breaks work into steps and identifies controls for each risk. It is used daily for tasks such as overhead piping, cutting, and lifting.

Gear such as hard hats, eye protection, gloves, and fall protection worn to reduce injury exposure. Employers must provide it and train workers in its proper use.