NC 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

NFPA 13 applies to commercial, industrial, and residential occupancies with 5 or more sprinklers. It does not cover one- and two-family dwellings, which fall under NFPA 13D.

Light hazard density

The minimum design density for light hazard occupancies is 0.10 gpm/ft² over a 1,500 ft² design area, with a maximum sprinkler spacing of 15 ft and 225 ft² per sprinkler.

Ordinary hazard Group 2

Ordinary Hazard Group 2 requires a design density of 0.20 gpm/ft² over 1,500 ft², with a maximum sprinkler spacing of 15 ft and a maximum protection area of 130 ft² per sprinkler.

Deflector distance

Sprinkler deflectors must be at least 1 in and no more than 12 in below a noncombustible ceiling, and at least 1 in and no more than 6 in below a combustible ceiling.

Dry system design area

The design area for a dry pipe system must be increased by 30% over the wet pipe design area to account for the delay in water delivery after the valve opens.

Residential sprinkler spacing

Under NFPA 13R, residential sprinklers must be listed for residential use, with a maximum spacing of 12 ft for 1/2 in sprinklers and 15 ft for 3/4 in sprinklers.

Concealed space protection

Combustible concealed spaces must be protected by sprinklers unless the space is filled with noncombustible material or is less than 6 in high with a noncombustible ceiling.

Wet alarm check valve

A wet alarm check valve at the riser opens on water flow to sound the alarm and must be provided with a main drain, pressure gauge, and waterflow alarm.

Sprinkler temperature color codes

Ordinary sprinklers (135-170°F) are orange, intermediate (175-225°F) are red, high (250-300°F) are yellow, and very high (325-375°F) are green.

Hanger spacing

Maximum hanger spacing is 12 ft for 1 in and 1¼ in pipe, 15 ft for 1½ in through 4 in pipe, and the first hanger must be within 3 ft of a sprinkler.

Sway bracing requirement

Sway bracing is required for systems with 2½ in and larger pipe and for pipe subject to seismic loads, with lateral bracing at intervals not exceeding 40 ft.

Dry pipe valve air pressure

A dry pipe valve must be listed and maintain air pressure of 20-40 psi, with a maximum of 60 psi; the air supply must restore system pressure within 30 minutes.

Inspector's test valve

The inspector's test valve is located at the most remote sprinkler and has a 5/8 in orifice; it is used to test the waterflow alarm and must sound within 90 seconds.

Fire department connection

The FDC must be located within 100 ft of a hydrant, be visible and accessible, be equipped with a check valve and drain, and be marked with system type and pressure.

Hazen-Williams formula

Friction loss per foot = 4.52 × Q^1.85 / (C^1.85 × d^4.87), where Q is gpm, d is inside diameter in inches, and C is the roughness coefficient (120 for steel).

Elevation pressure loss

Elevation loss is 0.433 psi per foot of rise; a 10 ft rise reduces pressure by 4.33 psi, and this loss is added to friction loss in the calculation.

Density/area method

Flow per sprinkler equals density (gpm/ft²) multiplied by the area protected by the sprinkler; the design area is the remote area with the most unfavorable hydraulics.

Hose stream allowance

The hose stream allowance is typically 100-250 gpm and is added to the sprinkler flow to determine total system demand, which must be less than the available supply.

Minimum sprinkler pressure

The minimum pressure at the most remote sprinkler is 7 psi for wet systems and 15 psi for dry systems; the maximum pressure at any sprinkler is 175 psi unless listed otherwise.

Water supply duration

Required water supply duration is 30 minutes for light hazard, 60-90 minutes for ordinary hazard, and 90-120 minutes for extra hazard occupancies per NFPA 13.

Standpipe classes

Class I standpipes serve the fire department, Class II serve occupants with 1½ in hose, and Class III serve both; residual pressure at the top outlet must be at least 100 psi.

Fire pump churn pressure

Churn pressure is the pump discharge pressure at zero flow; it must not exceed 140% of the rated pressure to protect the system from overpressure.

G.S. 87-13 license requirement

G.S. 87-13 defines a fire sprinkler contractor as a person engaged in installing, maintaining, or repairing sprinkler systems; a license is required to contract for this work.

State Board authority

G.S. 87-14 establishes the State Board of Examiners of Plumbing, Heating, and Fire Sprinkler Contractors, which examines applicants, issues licenses, and adopts rules.

Experience requirement

G.S. 87-15 requires an applicant for a fire sprinkler license to have at least 2 years of experience in the trade and to pass the Board's examination.

License renewal

G.S. 87-16 provides for annual license renewal; a license may be revoked or suspended for fraud, incompetence, or violation of the Board's rules.

21 NCAC Chapter 50

21 NCAC Chapter 50 sets the Board's fire sprinkler contractor rules, including examination content, experience documentation, continuing education, and disciplinary procedures.

Plan submittal

Before installation, the contractor must submit plans and specifications to the local fire marshal or code official showing design density, area of operation, pipe sizes, and water supply.

Permit requirement

A permit must be obtained from the local jurisdiction before installation begins; the permit must be posted on the job site and inspections requested at required stages.

Hydrostatic test

The system must be hydrostatically tested at 200 psi for 2 hours, or 50 psi above the maximum working pressure if greater; dry systems are tested at 13 psi air for 24 hours.

Underground flushing

Underground mains must be flushed at a velocity of at least 10 ft/s before connection to the sprinkler system, and the flush must be witnessed by the code official.

As-built documentation

At completion, the contractor must provide the owner with as-built drawings, hydraulic calculations, the owner's manual, and maintenance instructions for the system.