NC Fire Sprinkler cheat sheet

NFPA 13 governs commercial, industrial, and residential-occupancy systems of 5 or more sprinklers; NFPA 13R covers residential occupancies up to and including 4 stories; NFPA 13D covers one- and two-family dwellings and manufactured homes.

Light hazard density starts at 0.10 gpm/ft² over 1,500 ft²; Ordinary Group 1 at 0.15 gpm/ft² over 1,500 ft²; Ordinary Group 2 at 0.20 gpm/ft² over 1,500 ft²; Extra Hazard Group 1 at 0.30 gpm/ft² over 2,500 ft².

Design area may be reduced per the density/area curves only when the system has wet pipe, no unprotected vertical openings, and the ceiling is not combustible; reductions are limited to a maximum 25% for dry systems and 30% for quick-response sprinklers combined with wet systems.

Maximum sprinkler spacing for light hazard is 15 ft on branch lines with 225 ft² maximum protection area per sprinkler; ordinary hazard allows 15 ft spacing and 130 ft² per sprinkler.

Sprinkler deflector distance: 1 in minimum to 12 in maximum below noncombustible ceilings; 1 in minimum to 6 in below combustible ceilings; deflectors must be within 12 in of the ceiling for storage occupancies per clearance rules.

Sloped ceilings: sprinklers must be positioned so the deflector is parallel to the slope and within 12 in of the highest point or per the roof pitch rules in NFPA 13 Chapter 10.

Obstruction rules: sprinklers must be located within 12 in of the edge of an obstruction, or the obstruction must be at least 24 in wide and the sprinkler placed at a distance where spray coverage is maintained.

Quick-response sprinklers are required in light hazard occupancies where the ceiling height exceeds 20 ft and in certain residential occupancies; extended coverage sprinklers have specific listing limitations.

Hydraulic placard and design information must be attached to the riser; NFPA 13 requires the contractor to provide the design density, area of operation, and sprinkler identification.

Wet pipe systems use a check valve or alarm check valve at the riser; dry pipe systems require a dry pipe valve with an air supply and a quick-opening device when system capacity exceeds 750 gallons.

Sprinkler temperature ratings: ordinary 135-170°F, intermediate 175-225°F, high 250-300°F, very high 325-375°F; color codes are orange, red, yellow, green, blue, and purple respectively.

Glass bulb sprinklers are color-coded by temperature; fusible link sprinklers use solder with a rated temperature and must not be painted or modified.

Piping: Schedule 40 steel is standard for sprinkler piping; Schedule 10 is permitted for light and ordinary hazard when listed and installed per NFPA 13; CPVC is permitted in residential and light hazard per listing.

Hangers: maximum spacing for 1 in pipe is 12 ft, 1¼ in is 12 ft, 1½ in is 15 ft, 2 in is 15 ft, 2½ in is 15 ft, 3 in is 15 ft, 4 in is 15 ft; the first hanger must be within 3 ft of the sprinkler.

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

Alarm valves: a wet alarm check valve, dry pipe valve, preaction valve, or deluge valve must be provided with a main drain, gauge, and waterflow alarm.

Backflow prevention: a double check valve assembly or reduced pressure zone assembly is required by the local water authority; RPZ assemblies are required where there is a health hazard.

Fire department connections must be located within 100 ft of a hydrant and be visible and accessible; the FDC must be marked with the system type and pressure.

Available water supply is determined by flow test: static pressure, residual pressure, and flow in gpm; the results are plotted on a hydraulic graph and the available pressure at the test hydrant is extrapolated.

Hazen-Williams formula: friction loss = 4.52 × Q^1.85 / (C^1.85 × d^4.87) per foot of pipe, where Q is gpm, d is inside diameter in inches, and C is the roughness coefficient (120 for steel, 150 for cement-lined).

Total system demand = sprinkler flow at the design density plus hose stream allowance (typically 100-250 gpm) plus any inside/outside hose requirements; the demand must be less than the available supply at the residual pressure.

Density/area method: flow per sprinkler = density (gpm/ft²) × area protected by the sprinkler; the design area is the remote area with the most unfavorable hydraulic conditions.

Pump sizing: the fire pump must provide the required flow at the required pressure; churn pressure must not exceed 140% of rated pressure; the pump curve must be selected to meet the demand with a safety margin.

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

Pipe sizing: use the hydraulic calculation to verify velocity; velocities exceeding 20 ft/s in sprinkler piping may cause noise and erosion; 10-15 ft/s is typical for supply mains.

Standpipe systems: Class I for fire department use, Class II for occupant use with 1½ in hose, Class III for both; residual pressure at the topmost outlet must be at least 100 psi for Class I and III systems.

Water supply duration: light hazard 30 minutes, ordinary hazard 60-90 minutes, extra hazard 90-120 minutes per NFPA 13; storage duration is determined by the occupancy classification.

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

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.

G.S. 87-15 sets license requirements: an applicant must have at least 2 years of experience in the fire sprinkler trade and pass the examination; the Board may accept equivalent experience.

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

G.S. 87-17 authorizes the Board to require a surety bond or insurance; the Board may also require continuing education for license renewal.

21 NCAC 50.0100 et seq. sets the fire sprinkler contractor licensing rules, including examination content, experience documentation, and the requirement that a licensed contractor be responsible for each job.

21 NCAC 50.0200 addresses the licensing of fire sprinkler contractors and requires that the licensee be the person who supervises the installation; a firm must have a designated licensed contractor.

21 NCAC 50.0300 covers disciplinary actions, including fines, suspension, and revocation for violations such as working without a permit or failing inspections.

The Board's rules require that fire sprinkler plans be prepared by a licensed contractor or a qualified designer and be submitted to the local code official for review before installation.

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

A permit is required before beginning installation; the contractor must obtain the permit from the local jurisdiction and post it on the job site.

Inspections: the contractor must request a rough-in inspection after piping is installed and before concealment; a final inspection is required after the system is complete and tested.

Hydrostatic test: the system must be 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 pressure for 24 hours.

Flushing: underground mains must be flushed at a velocity of at least 10 ft/s before connection to the sprinkler system; the flush must be witnessed by the code official.

As-built drawings and hydraulic calculations must be provided to the owner at completion; the contractor must also provide the owner's manual and maintenance instructions.

Contract requirements: the contractor must have a written contract that includes scope, price, schedule, and warranty; changes must be documented in writing.

Insurance and bonding: the contractor must maintain general liability and workers' compensation insurance; a surety bond may be required for public projects.

Record keeping: the contractor must keep records of inspections, tests, and maintenance for at least the period required by the Board and the local jurisdiction.

NPSH: the fire pump must have sufficient net positive suction head available; a centrifugal pump requires NPSH available greater than NPSH required to avoid cavitation.

Flow test data: the static pressure is the pressure with no flow; the residual pressure is the pressure with flow; the pressure drop is the difference and is used to calculate the available water supply curve.

The hydraulic junction method: the most remote sprinkler is the starting point; the calculation proceeds back to the water supply, adding friction loss and elevation loss.

Elevation loss: 0.433 psi per foot of elevation; a 10 ft rise reduces pressure by 4.33 psi.

Friction loss in fittings is calculated using equivalent length; the equivalent length of a fitting is added to the pipe length.

The safety margin: the available pressure at the required flow must exceed the system demand by at least 10 psi or 10%, whichever is greater, per NFPA 13.

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

NFPA 13D systems require a minimum of 10 psi at the most remote sprinkler and a 10-minute water supply duration; the system must have at least one sprinkler in each dwelling.

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

Sprinkler coverage in storage occupancies: the design density is based on the storage height and commodity classification; the clearance between the deflector and the top of storage must be at least 18 in.

The 2019 edition of NFPA 13 is the edition adopted by the North Carolina Building Code; the contractor must verify the edition adopted by the local jurisdiction.

The maximum distance between the sprinkler and the wall is half the maximum spacing; for light hazard with 15 ft spacing, the maximum distance to the wall is 7.5 ft.

Sprinkler head orientation: upright sprinklers have the deflector above the frame; pendent sprinklers have the deflector below; sidewall sprinklers are mounted on the wall and have a specific spray pattern.

Dry pipe valves must be listed and have a maximum air pressure of 60 psi; the air supply must be capable of restoring the system pressure within 30 minutes.

The inspector's test valve must be located at the most remote sprinkler and have an orifice of 5/8 in; it is used to test the waterflow alarm.

The main drain valve must be located at the riser and be capable of draining the system at a rate of at least 1 in per hour.

The fire department connection must be equipped with a check valve and a drain; the FDC must be marked with the system type and pressure.

The alarm valve must be provided with a retarding chamber or a water motor gong; the alarm must sound within 90 seconds of water flow.

The contractor must provide a minimum of 1 year warranty on workmanship and materials; the warranty must be in writing.

The contractor must maintain a current license and display the license number on all contracts and advertisements.

The contractor must notify the Board of any change in the designated licensed contractor within 30 days.

The contractor must obtain a certificate of occupancy before the system is placed in service; the certificate is issued by the local code official after final inspection.

The contractor must provide the owner with a copy of the inspection and testing records within 10 days of the test.

The contractor must comply with the North Carolina Occupational Safety and Health Act (OSHA) requirements for worker safety on the job site.

G.S. 87-18 authorizes the Board to establish fees for examinations and licenses; the fees must be set by rule.

G.S. 87-19 provides that a person who violates the licensing law is guilty of a Class 2 misdemeanor; the Board may also seek an injunction.

21 NCAC 50.0400 sets the requirements for continuing education; the licensee must complete at least 6 hours per year, including 2 hours of code update.

21 NCAC 50.0500 addresses the licensing of fire sprinkler contractors and requires that the licensee have a minimum of 2 years of experience and pass a written examination.

The Board may issue a temporary license in an emergency; the temporary license is valid for 90 days and may be renewed once.

The Board's rules require that the contractor maintain a surety bond of at least $10,000 for fire sprinkler work; the bond must be filed with the Board.

The water supply curve is plotted as pressure versus flow; the available pressure at any flow is determined by the curve.

The demand point is the required flow and pressure; the system is adequate if the demand point lies below the supply curve.

The pump curve is plotted as pressure versus flow; the pump must be selected so the demand point lies on the pump curve with a safety margin.

The fire pump driver must be sized to provide the required horsepower; the brake horsepower is calculated from the flow, pressure, and pump efficiency.

The water supply duration is the time the supply must be able to provide the required flow; it is determined by the occupancy hazard.

The maximum pressure at any sprinkler is 175 psi; if the pressure exceeds this, a pressure reducing valve must be installed.

The design area for a dry pipe system must be increased by 30% over the wet pipe design area; the design area for a preaction system is also increased by 30%.

The design area for a sloped ceiling is increased by 30% when the slope exceeds 2/12; the increase is not required for residential systems.

The sprinkler spacing for a combustible concealed space is 12 ft maximum; the sprinkler must be located within 12 in of the ceiling.

The maximum spacing for extended coverage sprinklers is 20 ft for light hazard and 15 ft for ordinary hazard; the coverage area is limited by the listing.

The sprinkler deflector must be at least 1 in below the ceiling and no more than 12 in below the ceiling; the distance is measured from the deflector to the ceiling.

The sprinkler must be located at least 4 in from a wall; the maximum distance from a wall is half the maximum spacing.

The riser must be provided with a pressure gauge, a main drain, and a test valve; the gauge must be readable and located at the riser.

The system must be provided with a waterflow alarm that activates within 90 seconds of water flow; the alarm must be audible and visible.

The dry pipe system must have an air compressor or a nitrogen supply; the air pressure must be maintained at 20-40 psi.

The preaction system must have a detection system that activates the preaction valve; the detection system must be supervised.

The deluge system must have open sprinklers and a deluge valve; the valve is activated by a detection system.

The fire department connection must be located within 100 ft of a hydrant and must be visible from the street.

The contractor must submit a set of plans to the local fire marshal for review; the plans must be stamped by a licensed engineer if required by the jurisdiction.

The contractor must obtain a permit before starting work; the permit must be posted on the job site.

The contractor must request a rough-in inspection after the piping is installed and before it is concealed; the inspection must be documented.

The contractor must perform a hydrostatic test at 200 psi for 2 hours; the test must be witnessed by the code official.

The contractor must provide the owner with a copy of the as-built drawings and the hydraulic calculations within 30 days of completion.

The contractor must maintain a record of all inspections and tests for at least 3 years; the record must be available to the Board upon request.

G.S. 87-20 authorizes the Board to adopt rules for the licensing of fire sprinkler contractors; the rules must be consistent with the statute.

G.S. 87-21 provides that the Board may refuse to issue a license to a person who has been convicted of a felony involving fraud or dishonesty.

21 NCAC 50.0600 sets the requirements for the examination; the examination must cover the design, installation, and maintenance of fire sprinkler systems.

21 NCAC 50.0700 addresses the licensing of fire sprinkler contractors and requires that the licensee have a minimum of 2 years of experience and pass a written examination.

The Board may issue a license by reciprocity to a person licensed in another state if the requirements are substantially equivalent.

The Board's rules require that the contractor maintain a current license and display the license number on all contracts and advertisements.

The Hazen-Williams C factor is 120 for steel pipe, 150 for cement-lined cast iron, and 140 for copper; the C factor affects the friction loss.

The friction loss in a pipe is proportional to the flow raised to the 1.85 power and inversely proportional to the pipe diameter raised to the 4.87 power.

The equivalent length of a fitting is the length of straight pipe that would produce the same friction loss; the equivalent length is added to the pipe length.

The pressure loss due to elevation is 0.433 psi per foot; the elevation loss is added to the friction loss.

The available pressure at the water supply is the static pressure minus the friction loss in the supply main and the elevation loss.

The system demand is the sum of the sprinkler flow, the hose stream allowance, and the inside hose flow; the demand must be less than the available supply.

The design area for a light hazard system is 1,500 ft²; the design area for an ordinary hazard system is 1,500 ft²; the design area for an extra hazard system is 2,500 ft².

The density for a light hazard system is 0.10 gpm/ft²; the density for an ordinary hazard system is 0.15-0.20 gpm/ft²; the density for an extra hazard system is 0.30-0.40 gpm/ft².

The maximum spacing for a light hazard system is 15 ft; the maximum spacing for an ordinary hazard system is 15 ft; the maximum spacing for an extra hazard system is 12 ft.

The maximum protection area per sprinkler for a light hazard system is 225 ft²; for an ordinary hazard system it is 130 ft²; for an extra hazard system it is 100 ft².

The sprinkler deflector must be at least 1 in below the ceiling and no more than 12 in below the ceiling; the distance is measured from the deflector to the ceiling.

The sprinkler must be located at least 4 in from a wall; the maximum distance from a wall is half the maximum spacing.

The sprinkler head must be listed by a nationally recognized testing laboratory; the listing mark must be visible on the sprinkler.

The sprinkler head must be installed in accordance with the manufacturer's instructions; the instructions must be available on the job site.

The sprinkler head must not be painted, coated, or modified; any modification voids the listing.

The sprinkler head must be protected from damage by a guard or a shield if it is subject to damage.

The sprinkler head must be replaced if it is damaged or if it has been exposed to a fire; the replacement must be the same type and temperature rating.

The sprinkler head must be tested at least once every 5 years; the test must be documented.

The contractor must provide a written contract that includes the scope of work, the price, the schedule, and the warranty.

The contractor must obtain a permit before starting work; the permit must be posted on the job site.

The contractor must request a rough-in inspection after the piping is installed and before it is concealed; the inspection must be documented.

The contractor must perform a hydrostatic test at 200 psi for 2 hours; the test must be witnessed by the code official.

The contractor must provide the owner with a copy of the as-built drawings and the hydraulic calculations within 30 days of completion.

The contractor must maintain a record of all inspections and tests for at least 3 years; the record must be available to the Board upon request.

G.S. 87-22 authorizes the Board to adopt rules for the licensing of fire sprinkler contractors; the rules must be consistent with the statute.

G.S. 87-23 provides that the Board may refuse to issue a license to a person who has been convicted of a felony involving fraud or dishonesty.

21 NCAC 50.0800 sets the requirements for the examination; the examination must cover the design, installation, and maintenance of fire sprinkler systems.

21 NCAC 50.0900 addresses the licensing of fire sprinkler contractors and requires that the licensee have a minimum of 2 years of experience and pass a written examination.

The Board may issue a license by reciprocity to a person licensed in another state if the requirements are substantially equivalent.

The Board's rules require that the contractor maintain a current license and display the license number on all contracts and advertisements.