NE Fire Sprinkler flashcards
NE Fire Sprinkler · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Design density
- The minimum water flow rate in gallons per minute per square foot applied over the design area; selected from the occupancy hazard curve and used as the starting point for hydraulic calculations.
- Remote area
- The hydraulically most demanding area of sprinkler operation, typically 1,500 to 2,500 square feet depending on hazard, used as the assumed simultaneous operating area for calculations.
- K-factor
- A dimensionless discharge coefficient relating sprinkler flow to pressure by Q = K times the square root of P; larger K means more flow at the same pressure.
- Wet pipe system
- A system in which automatic sprinklers are connected to piping containing water under pressure at all times, so a fused head discharges water immediately.
- Dry pipe system
- Piping contains pressurized air or nitrogen; a dry pipe valve holds water back until a sprinkler fuses and air escapes, allowing water to enter and reach the heads.
- Preaction system
- A dry-pipe arrangement in which a supplemental detection system must operate before water fills the piping; single-interlock admits water on detection, double-interlock requires detection plus a fused head.
- Deluge system
- A system using open sprinklers or nozzles connected to piping that is dry until a deluge valve opens, then discharges water from all heads over the protection area at once.
- Hose stream allowance
- The water flow, in gallons per minute, reserved in the hydraulic calculation for fire department hose lines, added to sprinkler demand and varying with hazard classification.
- Light hazard
- An occupancy classification for low-combustibility contents and low heat release, such as offices, churches, and schools, permitting wider sprinkler spacing and lower design density.
- Ordinary Hazard Group 2
- An occupancy with moderate quantities of combustibles producing moderate heat release, such as machine shops and mercantile areas; requires higher density and closer spacing than Group 1.
- Extra Hazard Group 1
- An occupancy where combustibles are present in high quantity or with dust, lint, or flammable liquids producing rapid heat release; requires high density and large hose allowance.
- Standard spray sprinkler
- A sprinkler with a defined discharge pattern and spacing rule, installed upright or pendent, with a minimum operating pressure of 7 psi under the applicable standard.
- Control mode density area
- The traditional design method in which a specified density is applied over a specified remote area, assuming a limited number of sprinklers operate simultaneously.
- Design area increase for dry systems
- Dry pipe and double-interlock preaction systems require the remote area to be increased, commonly by 30 percent, because water travel time delays control of the fire.
- Sprinkler coverage area
- The floor area protected by one sprinkler, determined by the spacing between branch lines and between heads on a line; maximum area decreases as hazard increases.
- Deflector distance
- The required clearance between the sprinkler deflector and the ceiling, typically 1 to 12 inches for standard spray heads, ensuring the spray pattern develops properly.
- Riser and base of riser
- The vertical supply pipe feeding the system; hydraulic calculations must show required flow and pressure at the base of the riser, including hose stream allowance.
- Fire pump
- A pump installed to boost water supply pressure and flow to meet sprinkler demand; its rated point must satisfy the system demand curve, and churn pressure affects static loading.
- Backflow preventer
- A device preventing reverse flow from the sprinkler system into the potable water supply, often required by the authority having jurisdiction and adding friction loss to calculations.
- Waterflow switch
- A device that senses water movement in the sprinkler piping and initiates an alarm signal, typically required on each riser and on the alarm line of a wet system.
- Dry pipe valve
- A valve with a clapper held closed by air pressure on the system side; when air escapes through a fused sprinkler, the clapper opens and admits water.
- Accelerator
- A device attached to a dry pipe system that speeds the release of air pressure, allowing the dry pipe valve to open faster and reducing water delivery time to the heads.
- Inspection test and maintenance
- Periodic activities required by NFPA 25, including weekly or monthly gauge checks, annual main drain tests, and trip tests of dry valves, distinct from installation design rules.
- Main drain test
- A test conducted by opening the main drain on the riser and recording static and residual pressures to verify that the water supply and control valves are unobstructed.
- Design area adjustment for high-temperature sprinklers
- Where sprinklers with a high temperature rating are installed, the remote area may be reduced, reflecting the slower activation and fewer heads expected to operate at once.
- Minimum sprinkler pressure
- Seven psi is the lowest pressure at which a standard spray sprinkler may be designed to operate, regardless of calculated results, under the applicable installation standard.
- Pipe schedule design
- A prescriptive method assigning pipe sizes by the number of sprinklers served; permitted only for light and ordinary hazard occupancies within specified size and length limits.
- Branch line
- The pipe on which sprinklers are spaced; its size and the number of heads it carries are limited by hydraulic calculation or by the pipe schedule tables.
- Cross main
- The main pipe supplying branch lines on a single level; friction loss through the cross main must be included in the hydraulic calculation to the riser.
- Hazard classification
- The categorization of an occupancy by expected fire severity, which determines design density, remote area, sprinkler spacing, and hose stream allowance in the design.
- Flow test
- A test of the water supply, such as from a hydrant, measuring static and residual pressure and flow to establish the available supply curve for the hydraulic calculation.
- Hydraulic junction method
- The calculation technique of summing flows and computing friction loss from the remote area back to the supply, accounting for elevation and fitting losses along each path.