CO Fire Sprinkler flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

NFPA 13 scope

The standard for design and installation of automatic fire sprinkler systems in commercial, industrial, and institutional occupancies, covering hazard classification, hydraulic design, and acceptance testing.

Light hazard occupancy

Occupancy with low combustibility and low quantity of combustibles, such as offices, churches, and schools. Minimum design density is 0.10 gpm/ft² over 1,500 ft².

Ordinary Hazard Group 1

Occupancy with moderate combustibles and moderate stockpiles, such as parking garages and restaurants. Design density begins at 0.15 gpm/ft² over 1,500 ft².

Ordinary Hazard Group 2

Occupancy with higher combustibility or taller stockpiles, such as mercantile and machine shops. Design density begins at 0.20 gpm/ft² over 1,500 ft².

Sprinkler K-factor

Discharge coefficient relating flow to pressure by Q = K√P. A K=5.6 sprinkler flows about 21.7 gpm at 15 psi; higher K-factors deliver more flow at the same pressure.

Minimum end sprinkler pressure

The most remote sprinkler must have at least 7 psi residual pressure, and pressure must be high enough to produce the required density for the selected K-factor.

Design area

The remote floor area over which sprinkler density is calculated. It is 1,500 ft² for most light and ordinary hazard designs and is adjusted by density/area curves.

Dry-pipe system design area

Dry-pipe systems typically require the calculated design area to be increased by 30 percent to compensate for the delay while air is expelled and water reaches the sprinklers.

Maximum sprinkler spacing

Light hazard allows up to 15 ft between sprinklers and 15 ft between branch lines, with a maximum coverage of 225 ft² per sprinkler.

Ordinary hazard coverage limit

Maximum coverage area per sprinkler for ordinary hazard is 130 ft², with spacing generally not exceeding 15 ft on branch lines or between lines.

Hydrostatic test requirement

Sprinkler piping is tested at 200 psi for two hours, or at 50 psi above the maximum working pressure if that value exceeds 200 psi.

Main drain flow test

A test that flows water through the main drain to verify the water supply can deliver the required flow and pressure, confirming the supply curve used in design.

Inspector's test connection

A valve and orifice at the end of the most remote branch line that simulates a single sprinkler flow, used to verify alarm activation and water delivery.

Wet-pipe system

A system with water under pressure in the piping at all times. It is the most common and fastest-responding type, but cannot be used where piping may freeze.

Dry-pipe system

A system with pressurized air or nitrogen in the piping and water held back by a dry-pipe valve. It is used in unheated spaces and responds more slowly than wet systems.

Preaction system

A dry system with a detection system that must operate before the deluge or preaction valve releases water, protecting sensitive areas from accidental discharge.

Deluge system

A system with open sprinklers and a deluge valve that releases water to all sprinklers simultaneously when detection activates, used for high-hazard areas.

Pipe schedule design

A prescriptive method sizing pipe by the number of sprinklers served, limited to 160 or fewer sprinklers per NFPA 13. Larger systems require hydraulic calculations.

Hydraulic calculation

A calculation of pressure loss through piping, fittings, and sprinklers using friction loss formulas to confirm the supply can deliver the required density at the most remote sprinkler.

Hazen-Williams formula

A friction loss formula, P = 4.52 Q^1.85 / (C^1.85 d^4.87), used to calculate pressure loss in sprinkler piping where Q is flow, C is the roughness coefficient, and d is diameter.

C-factor for steel pipe

The Hazen-Williams roughness coefficient for new black steel pipe is 120; older or corroded pipe may be assigned a lower C-factor, increasing calculated friction loss.

Quick-response sprinkler

A sprinkler with a fast-responding thermal element that activates sooner than standard-response types, allowing reduced design areas in some occupancies under NFPA 13.

Sprinkler temperature rating

The activation temperature of the thermal element. Common ratings are 135°F, 155°F, 175°F, and 200°F; higher ratings are used near heat sources.

Deflector distance

The deflector must be positioned relative to the ceiling per listing, typically 1 to 12 inches below noncombustible ceilings, to form the required spray pattern.

Obstruction rule

Sprinklers must be positioned so construction or obstructions do not block spray. Obstructions wider than specified limits require additional sprinklers or shielding.

Sprinkler in closets

Small closets and concealed spaces may be exempt from sprinkler protection when combustibility and size limits in NFPA 13 are met, such as small noncombustible closets.

Anti-freeze system

A wet-pipe system filled with an antifreeze solution in areas subject to freezing. Solution concentration must be maintained and tested to keep the freeze point adequate.

Fire department connection

A connection allowing the fire department to pump supplemental water into the sprinkler system, typically required and sized based on the system demand.

Water flow alarm

A device that activates when water flows in the system, typically a vane or pressure switch, alerting occupants and the fire department to sprinkler operation.

Riser and main drain

The riser is the vertical supply pipe with control valves and alarms; the main drain valve allows flow testing to verify supply and detect obstructions.

Acceptance test sequence

After installation: hydrostatic test, flushing, alarm and valve testing, main drain flow test, and inspector's test connection flow to confirm the system meets design.

Design density vs. area

As required density increases on the density/area curve, the remote design area decreases, reflecting that higher-density designs address more severe hazards with less area.