fire-suppression

name	fire-suppression
description	Fire suppression systems — sprinkler design (NFPA 13), clean agent (FM-200/Novec 1230/CO₂), foam suppression (NFPA 11), water mist (NFPA 750), hydraulic calculations, hazard classification, pipe sizing, storage requirements.
metadata	{"priority":7,"promptSignals":{"phrases":["fire suppression","sprinkler system","NFPA 13","clean agent fire","FM-200","CO2 suppression"],"minScore":3}}

Fire Suppression Systems — Complete Skill

Hazard Classification (NFPA 13)

Light Hazard: offices, churches, hospitals, educational; low combustible content Ordinary Hazard Group 1: parking garages, laundries, bakeries; moderate combustibles Ordinary Hazard Group 2: machine shops, auto showrooms, woodworking; higher combustible load Extra Hazard Group 1: printing, die casting, metalworking with flammable liquids Extra Hazard Group 2: painting operations, open flammable liquid handling; highest sprinkler demand

High-Piled Storage (NFPA 13 Chapter 20): Commodity classes I–IV and rack storage; in-rack sprinklers may be required above 3.7 m (12 ft) storage height

Sprinkler System Design (NFPA 13)

Design Density and Area of Application

Hazard	Density [mm/min]	Design Area [m²]
Light	4.1	139
Ordinary Group 1	6.1	139
Ordinary Group 2	8.2–10.2	139–186
Extra Hazard 1	16.3	232
Extra Hazard 2	24.5	279

Sprinkler coverage area per head: Light/Ordinary: max 20.9 m² (225 ft²) per sprinkler Extra Hazard: max 9.3 m² (100 ft²) Maximum spacing: 4.6 m (15 ft) between heads

Hydraulic Design (Pipe Sizing)

Hazen-Williams equation (most common for fire suppression): P_loss = 6.05 × 10⁵ × Q^1.85 / (C^1.85 × d^4.87) [bar/m; Q in L/min; d in mm] C = pipe roughness factor: steel (new) C = 120; galvanized C = 100; CPVC C = 150

Flow from sprinkler head: Q = K × √P [L/min; K = K-factor [L/min/bar^0.5]; P = pressure at sprinkler [bar]] K-factors: 57 (standard), 80, 115, 161, 202, 242, 363 (large orifice)

Most Remote Sprinkler (worst-case design): Calculate pressure required at most remote head to achieve design density Work back to supply source including all pipe losses, elevation changes, valve losses

Pressure at most remote head: P_min = (Q_required / K)² [bar; Q_required = density × coverage area per head]

Water Supply Requirements

Total system flow (demand): Q_total = density × design area + hose stream allowance Hose allowance: 250–950 L/min (65–250 GPM) depending on hazard

Duration: Light/Ordinary: 60 min; Extra Hazard: 60–90 min; Storage: up to 120 min Supply check: fire pump curve + static pressure at connection ≥ system demand curve

System types:

• Wet pipe: always filled with water; fastest response; most common
• Dry pipe: pressurized air; for unheated spaces; activation slower (≤ 60 s)
• Pre-action: requires secondary detection + sprinkler activation; data centers, museums
• Deluge: all heads open; open nozzles; high-hazard processes

Clean Agent Suppression (NFPA 2001)

FM-200 (HFC-227ea) — Heptafluoropropane

Design concentration: 7.0–8.0% by volume in protected space (NOAEL = 9% for human safety) Extinguishing mechanism: primarily physical heat absorption (thermodynamic); minor chemical inhibition

Required agent mass: W = (V × ρ_agent / 100) × C / (100 - C) where V = room volume [m³]; ρ_agent = FM-200 vapor density [kg/m³]; C = design concentration [%] FM-200 density at 21°C: ρ_v = MW/22.4 × (273/294) = 7.08/22.4 × 0.929 = 0.294 kg/m³

Discharge time: NFPA 2001: ≤ 10 seconds for Class A/B; ≤ 10 seconds for Class C Storage: liquid in cylinders at 25 bar (360 psi); super-pressurized with nitrogen

Novec 1230 (FK-5-1-12) — NFPA 2001

Design concentration: 4.2–5.9% (NOAEL = 10%; large safety margin) Lower concentration → smaller cylinder footprint vs. FM-200 Zero ODP; GWP = 1 (very low) → preferred environmental option over HFCs

CO₂ Suppression (NFPA 12)

Total flooding concentration: 34% for most Class B/C hazards; 50% for gaseous fuel (inerting) Smothering mechanism: displaces O₂ below 15% → fire extinguishment

Design quantity: V_CO₂ = X × V_room [m³ at STP; X = volume fraction from NFPA 12 table] Mass: m = V_CO₂ × 1.977 kg/m³ (CO₂ density at STP)

Hazard to personnel: immediately dangerous to life and health (IDLH) at 4%; CO₂ systems require evacuation alarm + pre-discharge time delay ≥ 30 s High-pressure (HP) system: 56 bar (800 psi) cylinders; suitable for total flooding Low-pressure (LP) system: refrigerated at -18°C, 20 bar (300 psi); large volumes (>5,000 kg)

Foam Suppression (NFPA 11)

Applications: flammable liquid storage tanks, aircraft hangars, tank farms Foam types:

Type	Expansion Ratio	Application
AFFF (aqueous film-forming foam)	6:1–10:1	Hydrocarbon spills, fuel tanks
FFFP (film-forming fluoroprotein)	6:1	Hydrocarbon (splash resistance)
AR-AFFF (alcohol resistant)	6:1	Polar solvents (alcohol, ketones)
High-expansion foam	200:1–1000:1	3D confined fires, mines

Application rate (NFPA 11): Fixed-roof tanks: 4.1 L/min/m² for AFFF; 4.1 L/min/m² for surface application Open-top tanks: subsurface injection available with specially designed nozzles

Foam concentrate selection: 3% AFFF: mix 3% concentrate + 97% water = solution (proportioned) 6% FFFP: higher proportion; larger concentrate storage

Water Mist Systems (NFPA 750)

High-pressure water mist: P > 35 bar; droplet size Dv₀.₉ < 200 μm Low-pressure: P < 12 bar; droplets larger; more water flow needed

Mechanisms: evaporative cooling + oxygen displacement from steam + radiant heat attenuation Applications: machinery spaces, museums (low water damage), turbine enclosures, passenger ships (IMO MSC)

Droplet size specification: Dv₀.₅ = 50–100 μm (volume median diameter); measured by laser diffraction Flow rate: 1.5–3 mm/min application density (lower than sprinklers for some hazards)

Pipe Sizing and Pressure

Pipe schedule for fire suppression: Schedule 10 or 40 steel (ASTM A795 or A135); black steel standard; galvanized in corrosive areas Minimum pipe diameter: 25 mm (1 in) branch; 38 mm (1.5 in) cross-main minimum

Pressure regulators: Required when pressure exceeds 12.1 bar (175 psi) at sprinkler heads Pressure-reducing valves at zone control points

Fire pump (NFPA 20): Types: horizontal split-case, vertical turbine, end-suction Net positive suction head available (NPSHa) > NPSHr Pump rated at 150% flow at 65% of rated pressure; churn pressure ≤ 140% rated

Standards

Standard	Scope
NFPA 13	Installation of sprinkler systems
NFPA 2001	Clean agent fire extinguishing systems
NFPA 12	Carbon dioxide extinguishing systems
NFPA 11	Low-, medium-, high-expansion foam
NFPA 750	Water mist fire protection systems
NFPA 20	Installation of stationary pumps for fire protection
FM Global DS 2-0	Installation guidelines — FM Global

Output

Provide: hazard classification (NFPA 13 Light/Ordinary/Extra Hazard), system type (wet pipe/dry pipe/pre-action/deluge), design density [mm/min] and area [m²], K-factor and spacing of sprinklers, most remote head pressure [bar] and flow [L/min], total system demand [L/min] and duration [min], fire pump required flow and pressure, clean agent type and design concentration [%] (if applicable), agent mass required [kg] (if clean agent), CO₂ quantity [kg] and ventilation delay (if CO₂), foam type and application rate [L/min/m²] (if foam), pipe sizes and Hazen-Williams C-factor, and applicable standard (NFPA 13, NFPA 2001, NFPA 12).