Hazard Classification & Its Design Impact
The first step in designing any suppression system is determining the facility hazard classification per NFPA 13, as adopted in the UAE Civil Defence Code:
Light Hazard
Offices, churches, hospitals, hotels, schools — limited combustible content.
- Design Density: 4.1 L/min/m²
- Design Area: 139 m²
- Max area per sprinkler head: 18.6 m²
- Max distance from wall: 2.3 m
Ordinary Hazard Group 1
Car parks, bakeries, electronics manufacturing, laundry facilities.
- Design Density: 8.2 L/min/m²
- Design Area: 139 m²
- Max area per head: 12.1 m²
Ordinary Hazard Group 2
General merchandise warehouses, metalworking, rubber processing, car showrooms.
- Design Density: 12.2 L/min/m²
- Design Area: 139 m²
- Max area per head: 12.1 m²
Extra Hazard Group 1
Repair workshops, sawmills, die casting, petroleum distillation.
- Design Density: 16.3 L/min/m²
- Design Area: 232 m²
- Max area per head: 9.3 m²
Extra Hazard Group 2
Flammable liquid storage warehouses, furniture manufacturing, dip-coating operations.
- Design Density: 24.5 L/min/m²
- Design Area: 232 m²
- Max area per head: 9.3 m²
Sprinkler Head Types & Classifications
Pendent Sprinkler
Installed with head facing down — most common type. Deflector must be 25–305 mm from ceiling. No obstruction permitted within 460 mm below deflector.
Upright Sprinkler
Installed with head facing up — suited for exposed pipework in warehouses. Deflector 25–100 mm above the centre of the head.
Sidewall Sprinkler
Mounted on walls — suited for narrow corridors and rooms with limited ceiling access. Fan-shaped forward and side discharge pattern.
Concealed Sprinkler
Recessed into ceiling with a fusible cover plate (typically 57°C) — used in hotels and premium offices for aesthetic purposes.
ESFR Sprinkler (Early Suppression Fast Response)
Specifically designed for high-piled storage warehouses (above 3.5 m storage height). Eliminates the need for in-rack sprinklers. Coverage up to 9.3 m² per head at very high design density.
Sprinkler Temperature Ratings — Colour Code
| Temperature Rating | Temperature | Bulb Colour | Common Application |
|---|---|---|---|
| Ordinary | 57–77°C | Red / Orange | Offices, hotels, hospitals |
| Intermediate | 79–107°C | Yellow / Green | Glass roofs, enclosed car parks |
| High | 121–149°C | Blue | Steam areas, dryers |
| Extra High | 163–191°C | Purple | Ovens, internal flues |
| Ultra High | 204–246°C | Black | Highly specialised applications |
Precise Spacing Requirements (NFPA 13)
- Minimum distance between sprinklers: 1.8 m (to prevent cold-soldering between adjacent heads)
- Maximum distance from wall: Half of maximum spacing (Light Hazard: 2.3 m; Ordinary: 2.3 m)
- Clearance below deflector: No obstruction within 460 mm below deflector
- Structural beams: Beams deeper than 250 mm are treated as walls and require an additional sprinkler
- Sloped ceilings: Additional sprinkler required at the ridge
- Concealed spaces: Electrical rooms and false ceilings exceeding 100 mm depth require sprinkler coverage
Portable Fire Extinguishers — Detailed Requirements
Per NFPA 10 and the UAE Civil Defence Code, portable extinguishers are mandatory in all facilities regardless of sprinkler installation:
Class A — Ordinary Combustibles
- Light Hazard: 2-A rating per 278 m², max travel distance 23 m
- Ordinary Hazard: 2-A rating per 139 m², max travel distance 23 m
- Extra Hazard: 4-A rating per 93 m², max travel distance 15 m
Class B — Flammable Liquids & Gases
- 5-B to 10-B rating: Max travel distance 15 m
- 10-B and above: Max travel distance 9 m
Class K — Commercial Kitchens
- Wet chemical extinguisher specifically rated for commercial cooking
- One required per cooking appliance using oils or fats with capacity above 2 litres
- Maximum travel distance: 9 m from the appliance
General Installation Requirements
- Mounting height: Handle at 1.0–1.5 m from floor for extinguishers under 18 kg
- Securing: Wall bracket or dedicated cabinet — never placed directly on floor
- Monthly check: Visual inspection of seal and pressure gauge
- Annual inspection: By a certified technician
- Pressure test: Every 5 years for dry powder and CO₂; every 12 years for foam
Fire Pumps — NFPA 20 & UAE Code Requirements
The pump is the heart of the sprinkler system — among the most critical elements in the suppression network:
- Main electric pump: Designed to deliver the required pressure and flow at all design points
- Diesel backup pump: Mandatory where fire could interrupt the electricity supply. Must operate without mains power
- Jockey pump: Small pressure-maintaining pump that detects minor leaks in the system
- Water storage tank: Must provide 30–60 minutes of full-system operation (per design)
- Testing: Weekly no-flow start test + full annual performance test
Practical Examples
General Storage Warehouse 2,000 m² (Ordinary Hazard Group 2): 2,000 ÷ 12.1 = 166 sprinkler heads minimum. Design density: 12.2 L/min/m². Design area: 139 m² → pump flow: 139 × 12.2 = 1,696 L/min minimum.
Commercial Office 500 m² (Light Hazard): 500 ÷ 18.6 = 27 sprinkler heads. Design density: 4.1 L/min/m². Required flow: 139 × 4.1 = 570 L/min.
Extinguishers for 1,000 m² Warehouse (OH1): 1,000 ÷ 139 = 7.2 → minimum 8 extinguishers rated 2-A, distributed so no point exceeds 23 m travel distance to the nearest unit.
System Integration in the UAE
- Sprinklers + Alarm: Water flow from any head activates the flow switch, sending a signal to the alarm panel
- Pumps + Alarm: Pumps start automatically on pressure drop in the system
- Isolation valves: Must remain open at all times and be electronically monitored (tamper switch)
- Tank + BMS: Tank level monitoring integrated into the building management system