# Sprinkler System Design Automatic sprinkler systems are the most effective single measure for controlling fire in buildings. They detect heat, activate locally, and suppress or control fire while it is still small — protecting life, limiting property damage, and enabling design flexibilities such as extended travel distances and larger compartments. The architect must understand sprinkler system types, design integration, and the spatial requirements for pipework, tanks, pump rooms, and sprinkler heads. --- ## Table of Contents - [Sprinkler System Types](#sprinkler-system-types) - [Hazard Classification](#hazard-classification) - [Sprinkler Head Types](#sprinkler-head-types) - [Design Parameters](#design-parameters) - [Water Supply](#water-supply) - [Architectural Coordination](#architectural-coordination) - [Design Flexibilities](#design-flexibilities) - [Standards](#standards) - [See Also](#see-also) --- ## Sprinkler System Types | Type | Description | Application | |------|-------------|-------------| | **Wet pipe** | Pipes permanently charged with water; heads activate individually by heat | Most buildings; heated environments | | **Dry pipe** | Pipes charged with compressed air; water released when head activates | Unheated spaces (car parks, loading bays, freezer stores) | | **Pre-action** | Dry pipe requiring both detector signal and head activation to release water | Data centres, museums, archives (prevents accidental discharge) | | **Deluge** | All heads open simultaneously on detector signal | High-hazard industrial, aircraft hangars | | **Residential** | Smaller heads, lower flow, designed for dwelling fires | Residential buildings (BS 9251) | --- ## Hazard Classification ### BS EN 12845 | Class | Description | Examples | |-------|-------------|---------| | **Light Hazard (LH)** | Low fire load, non-combustible contents | Offices, hotels, hospitals, schools | | **Ordinary Hazard 1 (OH1)** | Moderate fire load | Car parks, restaurants, laundries | | **Ordinary Hazard 2 (OH2)** | Moderate-high fire load | Workshops, retail, stages | | **Ordinary Hazard 3 (OH3)** | Moderate-high with combustible goods | Large retail, exhibition halls | | **High Hazard (HH)** | High fire load, flammable materials | Industrial, warehousing, paint shops | ### NFPA 13 | Class | Description | |-------|-------------| | **Light** | Offices, educational, institutional | | **Ordinary Group 1** | Parking garages, restaurants, bakeries | | **Ordinary Group 2** | Dry cleaners, libraries, machine shops | | **Extra Hazard Group 1** | Printing, woodworking | | **Extra Hazard Group 2** | Flammable liquid handling, plastics processing | --- ## Sprinkler Head Types | Head Type | Activation | Application | |-----------|-----------|-------------| | **Pendant** | Hangs below pipe; deflects water downward in umbrella pattern | Most common — suspended ceilings | | **Upright** | Mounted on top of pipe; deflects water upward then down | Exposed ceilings, industrial | | **Sidewall** | Mounted on wall; deflects water across room | Corridors, hotel rooms, residential | | **Concealed** | Hidden behind cover plate (drops at temperature) | Architectural ceilings, hotels, residential | | **Flush** | Partially recessed into ceiling | Minimised visual impact | | **ESFR** | Early Suppression Fast Response — high-volume rapid discharge | High-rack warehousing | | **Residential** | Fast-response, designed for room of origin | Dwelling rooms | ### Temperature Ratings | Colour Code | Activation Temperature | Application | |------------|----------------------|-------------| | **Uncoloured/Orange** | 57°C | Standard (most spaces) | | **White** | 68°C | Standard (most common) | | **Blue** | 79°C | Kitchens, boiler rooms | | **Red** | 93°C | High ambient temperature areas | | **Green** | 141°C | Saunas, industrial ovens | --- ## Design Parameters ### BS EN 12845 Design Densities | Hazard | Design Density | Assumed Simultaneous Area | |--------|---------------|--------------------------| | LH | 2.25 mm/min | 84 m² | | OH1 | 5.0 mm/min | 72 m² | | OH2 | 5.0 mm/min | 144 m² | | OH3 | 5.0 mm/min | 216 m² | | HH | 7.5–30 mm/min | 260+ m² | ### Spacing | Hazard | Maximum Coverage per Head | Maximum Spacing | |--------|--------------------------|----------------| | LH | 21 m² | 4.6m × 4.6m | | OH | 12 m² | 3.7m × 3.7m (typical) | | HH | 9 m² | 3.0m × 3.0m | ### Minimum Clearances | Clearance | Distance | |-----------|----------| | Head to ceiling | 25–300mm (type-dependent) | | Head to obstruction | 3× depth of obstruction | | Head to wall | Half the maximum spacing | | Head to head (minimum) | 2.0m | --- ## Water Supply | Requirement | LH | OH1–OH3 | |-------------|-----|---------| | **Duration** | 30 min | 60 min | | **Tank size** | ~6,000–12,000 L | 40,000–250,000+ L | | **Pump capacity** | Duty + standby (diesel) | Duty + standby | ### Water Supply Types | Source | Description | |--------|-------------| | **Town main** | Direct from municipal supply (if pressure/flow adequate) | | **Elevated tank** | Gravity feed from roof or tower tank | | **Ground-level tank + pump** | Steel or concrete tank with electric + diesel fire pumps | | **Combined** | Town main + tank for peak demand | ### Pump Room Requirements | Element | Specification | |---------|--------------| | Location | Ground floor or basement; direct access from outside | | Size | 20–40 m² typical (pump set, controller, test connections) | | Ventilation | For diesel pump: combustion air + radiator cooling | | Drainage | Floor drain for test water and leaks | | Power | Independent supply; backup diesel pump for power failure | | Signage | "SPRINKLER PUMP ROOM" externally | --- ## Architectural Coordination | Element | Coordination Issue | |---------|-------------------| | **Ceiling grid** | Sprinkler heads must align with or accommodate ceiling tile grid | | **Ceiling void** | 300–500mm minimum for pipework above ceiling | | **Exposed pipework** | In industrial/exposed ceiling designs, coordinate routing and colour | | **Risers** | Wet riser shaft 300×300mm minimum per floor | | **Tank location** | Ground floor or basement; significant structural load (water = 1 tonne/m³) | | **Valve sets** | Flow switches, alarm valves, drain valves — accessible locations | | **Fire brigade inlet** | External connection for fire service boosting | | **Thermal insulation** | Dry pipe systems need trace heating if exposed to freezing | --- ## Design Flexibilities Sprinklers enable compensatory design relaxations in many building codes: | Relaxation | Benefit | |-----------|---------| | Extended travel distances | +50–100% increase in permitted escape distances | | Larger compartments | Double or more compartment size | | Reduced structural fire resistance | From 120 to 90 or 60 minutes in some cases | | Open-plan design | Larger uninterrupted floor plates | | Reduced insurance premiums | Significant reductions for fully sprinklered buildings | | Atrium design | Sprinklered atria may not require smoke curtains | These relaxations vary by jurisdiction and must be agreed with the approving authority. See [[Fire Safety Building Regulations]] and [[Means of Egress Requirements]]. --- ## Standards | Standard | Jurisdiction | Scope | |----------|-------------|-------| | **BS EN 12845** | UK/Europe | Commercial/industrial sprinkler design | | **BS 9251** | UK | Residential sprinkler systems | | **NFPA 13** | USA/International | Standard for Installation of Sprinkler Systems | | **NFPA 13R** | USA | Residential occupancies up to 4 storeys | | **NFPA 13D** | USA | One- and two-family dwellings | | **FM Global** | International | Insurance-driven enhanced standards | --- ## See Also - [[Fire Alarm Systems]] - [[Fire Safety Building Regulations]] - [[Fire Engineering Principles]] - [[Smoke Extraction Systems]] - [[Means of Egress Requirements]] - [[architecture/Building Services/Fire Protection Systems/Fire Protection Systems]] --- #sprinkler #fire-protection #fire-safety #water-supply #building-services #life-safety