PE Fire Protection cheat sheet

T-squared growth model: Q = αt², with α = 0.00293 kW/s² (slow), 0.0117 (medium), 0.0469 (fast), and 0.1876 (ultrafast).

Flashover criteria: upper-layer gas temperature near 600 °C, radiant flux at floor level near 20 kW/m², or transition from growth to fully developed burning.

Ventilation-controlled burning rate: ṁ = 0.5 A√H kg/s, where A is total opening area (m²) and H is weighted opening height (m).

Standard fire curve: T = 20 + 345 log10(8t + 1) °C with t in minutes, per ASTM E119 and ISO 834.

Heskestad flame height: L = 0.235 Q^(2/5) − 1.02 D, with L and D in meters and Q in kW.

Radiant flux thresholds: about 2.5 kW/m² for pain onset, 10 kW/m² for severe burns in seconds, 20 kW/m² associated with flashover of room contents.

Risk = probability × consequence; hazard identification precedes frequency and consequence analysis, and results are compared against tolerability criteria such as ALARP.

Heat transfer modes are conduction, convection, and radiation; radiation dominates from hot surfaces above roughly 500 °C, while convection governs smoke transport in the upper layer.

NFPA 101 = Life Safety Code; NFPA 1 = Fire Code; NFPA 13 = sprinkler systems; NFPA 72 = detection and alarm; NFPA 25 = ITM of water-based systems; NFPA 20 = stationary fire pumps.

IBC Chapter 7 governs fire-resistance-rated construction, Chapter 9 fire protection systems, and Chapter 10 means of egress.

IBC occupancy groups: A (assembly), B (business), E (educational), F (factory), H (high hazard), I (institutional), M (mercantile), R (residential), S (storage), U (utility).

IBC Table 1004.5 occupant load factors: business 150 gross, mercantile 60 gross, assembly unconcentrated 15 net, assembly concentrated 7 net, classrooms 20 net.

The adopted code edition and local amendments control; the AHJ may approve alternative materials or methods where equivalent fire safety is documented under equivalency provisions.

NFPA 14 = standpipe and hose systems; NFPA 11 = foam; NFPA 12 = CO2; NFPA 2001 = clean agent; NFPA 90A = installation of air-conditioning and ventilating systems.

Required fire flow derives from IFC Appendix B or NFPA 1 based on construction type, occupancy, and exposure; required duration increases with the fire flow demand.

Referenced standards are enforceable only in the specific edition and with the amendments adopted by the jurisdiction.

NFPA 72 smoke detector spacing on smooth ceilings: 30 ft (9.1 m) nominal, with the first detector within 0.7 times the spacing (about 21 ft) of a sidewall.

Heat detectors are offset from walls by half the listed spacing, and the listed spacing must be reduced for ceiling heights above 10 ft using the NFPA 72 spacing-reduction curves.

Public mode notification: at least 15 dBA above average ambient or 5 dBA above maximum ambient lasting over 60 s, not less than 75 dBA at 10 ft, and never more than 110 dBA.

A sprinkler waterflow alarm must actuate within 90 s of a sustained flow sufficient to operate a sprinkler; valve tamper switches must be monitored and annunciated.

NFPA 90A requires duct smoke detectors where an air-handling unit exceeds 2,000 cfm and serves more than one story or more than 15,000 ft².

Class A initiating device and notification circuits survive a single open or ground fault; Class B circuits do not and use two conductors without a return path.

Ionization detectors respond faster to flaming fires with small particles; photoelectric detectors respond faster to smoldering fires with larger smoke particles.

NFPA 72 supervising station categories are central station, proprietary, remote supervising, and auxiliary, distinguished by who receives signals and how the premises connect.

NFPA 13 baseline densities over 1,500 ft²: light hazard 0.10 gpm/ft², ordinary Group 1 0.15, ordinary Group 2 0.20, extra hazard Group 1 0.30 gpm/ft².

Sprinkler flow: Q = K√P; common K-factors are 5.6, 8.0, 11.2, 14.0, 16.8, 22.4, and 25.2 gpm/psi^0.5.

Dry-pipe and double-interlock preaction systems require the hydraulically calculated design area to be increased 30% over the wet-system area for the same hazard.

NFPA 20 fire pump: at least 150% of rated flow at not less than 65% of rated head, with churn (shutoff) pressure not exceeding 140% of rated pressure.

Hazen-Williams friction loss: p = 4.52 Q^1.85 / (C^1.85 d^4.87), with p in psi/ft, Q in gpm, d in inches, and C the roughness coefficient.

NFPA 14 standpipes: Class I provides 2.5 in. outlets sized for 500 gpm at 100 psi residual; Class II provides 1.5 in. outlets for 100 gpm at 65 psi; Class III provides both.

NFPA 25 requires a weekly no-flow (churn) run of fire pumps and an annual flow test recording churn, 100%, and 150% of rated flow.

NFPA 2001 clean agent total flooding requires the design concentration be maintained for 10 minutes in occupied spaces and kept below the NOAEL where people are present.

Egress capacity: IBC requires 0.2 in. per occupant on level components and 0.15 in. on stairs; NFPA 101 requires 0.2 in. and 0.3 in. respectively.

Travel distance (IBC Table 1017.2): 200 ft unsprinklered and 250 ft sprinklered for most business and mercantile occupancies, with shorter limits for hazardous uses.

Dead-end corridors are limited to 20 ft in nonsprinklered buildings and 50 ft where sprinklers are provided, measured from where the single path begins.

Egress doors: 32 in. minimum clear width, 80 in. minimum clear height, and swinging in the direction of travel where the occupant load is 50 or more.

Stairway width: 44 in. minimum in IBC, with 36 in. permitted by NFPA 101 for low-occupant conditions; handrails 34–38 in. above tread nosing and guards at 42 in.

NFPA 92 stair pressurization typically maintains 0.05–0.10 in. w.c. differential across closed doors, with opening force limited to 30 lbf.

Interior finish per ASTM E84: Class A flame spread 0–25, Class B 26–75, Class C 76–200, with smoke-developed index limits also applied in egress paths.

Structural fire resistance from IBC Table 601 by construction type: Type IA = 3 hr, Type IB = 2 hr, Type IIA = 1 hr; shaft enclosures are typically 2 hr.