OK Fire Sprinkler cheat sheet

NFPA 13 governs sprinkler system design and installation; NFPA 25 governs ITM; NFPA 20 covers fire pumps; NFPA 24 covers private fire service mains; NFPA 14 covers standpipes; NFPA 72 covers alarm initiation.

The adopted code edition plus local amendments controls; where documents conflict, the more restrictive requirement applies unless the AHJ formally grants an alternative.

A permit and approved working plans are required before new installation or alteration; emergency repairs may proceed only as allowed by the AHJ and must be documented.

Working plans normally include hydraulic calculations, floor plans, riser/control-valve diagram, hanger and seismic details, water-supply test data, and equipment listings.

Contractor and individual qualifications must match the jurisdiction's licensing statute and rules; scope, insurance, and qualification should be verified before work begins.

Required inspections typically include underground, rough-in, hydrostatic, alarm/flow, and final; the AHJ must be notified and approved plans kept onsite.

Closeout records include as-built plans, calculations, material and test certificates, contractor's material and test certificate, and acceptance test results.

Licensing administration includes renewal, continuing education, qualifier employment, and notification of changes; verify current state requirements because they change.

Sprinkler flow: Q = K√P; pressure: P = (Q/K)², with Q in gpm, K in gpm/psi^0.5, and P in psi.

Remote-area flow = design density (gpm/ft²) × design area (ft²); hose and fixed demands are added at the base of the riser.

Hazen-Williams US units: p = 4.52 Q^1.85 / (C^1.85 d^4.87) psi/ft, with Q in gpm and internal diameter d in inches.

Elevation changes add or subtract 0.433 psi per foot of water; device, valve, backflow, and fitting losses must also be included.

A water-supply test records static, residual, and flow pressure; results are adjusted to the design flow and worst credible supply condition.

The demand point (sprinkler + hose + other flow at required pressure) must lie below the adjusted supply curve at the system connection.

The remote area is the hydraulically most demanding area; dry-pipe, double-interlock preaction, sloped ceilings, and obstructions can increase the required area.

Node balancing sums flows and pressure losses; a calculation is incomplete until every node's flow and pressure satisfy the governing equations.

Fire pump pressure is added per the pump curve, but pump pressure falls as flow rises; suction losses and maximum churn pressure must be checked.

Occupancy hazard classes are light hazard, ordinary hazard groups 1 and 2, and extra hazard groups 1 and 2; the class selects density and area.

NFPA 13 remote design areas are generally not less than 1,500 ft², with exceptions and adjustments in the standard.

Dry-pipe and double-interlock preaction systems require a design-area increase, commonly 30 percent unless the standard's specific limits modify it.

Wet pipe is permitted where piping is not subject to freezing; dry pipe is for unheated spaces; preaction protects against accidental water discharge.

Deluge systems use open heads and a detection system to trip a deluge valve; they are used for special hazards requiring area-wide application.

Residential systems follow NFPA 13R or 13D, not NFPA 13; their design criteria and allowable building heights differ.

Storage design depends on commodity class, storage height, aisle width, ceiling height, and sprinkler type; ESFR, CMSA, and CMDA are not interchangeable.

Hose-stream allowance is added to sprinkler demand and varies with occupancy hazard and system type.

Sprinkler coverage limits for standard spray heads are commonly 225 ft² light hazard, 130 ft² ordinary hazard, and 100 ft² extra hazard, subject to spacing rules.

A sprinkler is specified by K-factor, temperature rating, response type, orientation, and listing; substituting one attribute can invalidate the design.

Common temperature classes: ordinary 135–170°F, intermediate 175–225°F, high 250–300°F, extra-high 325–375°F.

Standard spray deflectors are generally 1 in to 12 in below the ceiling; listed special sprinklers may have different distances.

Control valves must be supervised open; OS&Y, indicator butterfly, and post-indicator valves show position.

Alarm check valves, dry-pipe valves, preaction valves, and deluge valves must be listed and installed with the required trim and drains.

Waterflow switches and pressure switches initiate alarms; their location and sensitivity must match the listing and NFPA 72.

Spare sprinklers and matching wrenches are kept in a cabinet; required quantities depend on the number of installed sprinklers.

Gauges are required on supply, system, and pump suction/discharge as applicable; gauge range and calibration matter for acceptance and ITM.

Sprinkler pipe and fittings must be listed or approved for fire protection; use the standard's pipe schedule or hydraulic calculation method.

Steel pipe may be threaded, grooved, welded, or flanged as listed; cut grooves reduce wall thickness and must meet the listing.

CPVC is limited to listed applications and must be joined with specified solvent cement; allow cure time before pressure testing.

Underground mains require approved material, bedding, thrust restraint, and corrosion protection; metallic pipe needs coating or cathodic protection where required.

Dissimilar metals need dielectric isolation or approved transition fittings to limit galvanic corrosion.

Fittings and valves add equivalent-length friction loss; do not omit them from hydraulic calculations.

Reaming, deburring, and clean joints are required; weld procedures and welder qualifications apply where welding is used.

Hydrostatic testing is performed before concealment and after repairs; test pressure and duration follow NFPA 13 and the AHJ.

Hangers support dead weight and must be attached to building structure, not to ducts, electrical conduit, or other nonstructural elements.

Hanger spacing depends on pipe size and material; larger steel pipe permits longer spacing, while CPVC and copper have separate limits.

A hanger is generally required within a specified distance of the end of a branch line and at changes in direction; follow the standard's table.

Seismic sway bracing resists lateral and longitudinal movement; bracing is required where the adopted seismic design category triggers it.

Lateral braces control side-to-side movement; longitudinal braces control along-axis movement; both must connect to structural members.

Flexible couplings, expansion loops, and seismic separation assemblies accommodate building movement and pipe expansion.

Hanger rods must not be bent, cut, or welded without approval; rod diameter and attachment capacity must match the load.

Piping must maintain required clearance from structure, other trades, and moving equipment; sleeves and firestopping are used at penetrations.

NFPA 20 fire pumps must be listed; the pump curve, driver, controller, and accessories are selected as a package.

At rated flow the pump produces rated head; at 150 percent rated flow the head must be at least 65 percent of rated head, and shutoff head must not exceed 140 percent.

A jockey pump maintains pressure during minor leakage; it must not be sized to satisfy fire demand or replace the main fire pump.

Fire pump suction must provide sufficient net positive suction head; inadequate NPSH causes cavitation and loss of performance.

Water storage tanks require a dedicated fire-protection reserve, anti-vortex plate, fill and drain provisions, and freeze protection.

Pump controllers start the pump automatically on pressure drop; manual shutdown and automatic restart features follow NFPA 20 and NFPA 25.

A backflow preventer or suction strainer can reduce available pressure; its loss must be included in the hydraulic calculation.

Churn, rated-flow, and 150-percent flow tests document pump performance; results are compared with the certified curve.

Plan review checks occupancy classification, density/area, hydraulic calculations, water supply, sprinkler layout, hanger/seismic details, and fire pump selection.

Approved plans must be onsite and match the installation; field changes require revised plans and AHJ approval before proceeding.

Rough-in inspection verifies pipe size, material, hanger spacing, sprinkler locations, clearances, and concealment before closure.

Final inspection verifies valves, alarms, test connections, signage, spare heads, and completion of acceptance tests.

Permits are required for new systems, alterations, additions, and some repairs; the AHJ determines what qualifies as a minor repair.

An impairment tag and notification are required when a system is out of service; a fire watch or alternate protection may be required.

Correction notices must be cleared and reinspected; a failed inspection can stop occupancy or water service.

Firestopping and penetration protection are inspected where piping passes through rated assemblies.

Acceptance testing includes hydrostatic test, flushing, main drain flow, alarm and supervisory signal tests, and pump or dry-valve trip tests.

NFPA 13 hydrostatic test is commonly 200 psi for two hours; where working pressure exceeds 150 psi, test at 50 psi above working pressure.

Flushing removes debris before connection of sprinklers and valves; underground flushing precedes aboveground flushing.

A main drain test compares static and residual pressure; a significant change from baseline can indicate a closed valve or supply problem.

Dry-pipe and preaction valves require trip tests to confirm operation and water delivery; test frequency and timing follow NFPA 25.

NFPA 25 requires monthly, quarterly, annual, and multi-year ITM tasks; examples include gauge checks, alarm tests, main drain tests, and internal inspections.

Gauges are replaced or calibrated at required intervals; a failed gauge can invalidate acceptance or ITM records.

ITM records must identify the component, date, tester, result, and corrective action; impairments are tracked until restored.

Before work, isolate and lock out electrical, pneumatic, and hydraulic energy; verify zero energy and bleed stored pressure.

Hot work requires a permit, combustible clearance, fire extinguishing equipment, and a fire watch during and after the task.

Coordinate sprinkler routing with structural, HVAC, electrical, and ceiling trades before installation to avoid clashes and rework.

Pressure testing can eject plugs and caps; restrain test equipment, stand clear, and never exceed the test pressure.

Trenching and excavation require location of utilities, protective systems, access/egress, and atmospheric testing where required.

A system impairment requires owner and AHJ notification and may require a fire watch; restoration must be documented.

Use fall protection, guarded openings, and safe access when working at ceilings, roofs, and tank exteriors.

Keep solvent cements, fuels, and cylinders away from ignition; follow SDS and ventilation requirements.