Design and Installation of Fixed Automatic Sprinkler Fire Extinguishing Systems - Code of Practice
2002 Edition

Per the guidelines in Clause 8.1 and Table 3, the minimum design water densities and maximum operating areas for sprinkler systems are as follows: Light hazard requires 2.25 l/min/m² over an area of 84 m²; moderate hazard needs 5.00 l/min/m² over 360 m²; and high hazard demands 9.00 l/min/m² over 260 m². These values ensure sufficient water supply aligned with the occupancy risk classification.

Recommended sprinkler types vary by hazard class: For light hazards, ceiling/flush, concealed, spray, sidewall, and conventional sprinklers are suitable, generally with 15 or 20 mm orifices. Moderate hazards allow all types including spray and sidewall sprinklers with 15 or 20 mm sizes. High hazard areas typically use conventional or spray pattern sprinklers only, sized 15 or 20 mm. Selection should consider the nature of the hazard and installation environment.

Hydraulic calculations involve determining flow rates based on design criteria, calculating pressure losses using formulas such as Darcy-Weisbach or Hazen-Williams, and selecting appropriate pipe sizes to maintain velocities typically between 0.6 and 3 m/s to avoid noise and erosion. Hydraulic balancing ensures uniform flow distribution through adjustments in pipe dimensions or balancing valves. Accurate input data for hazard class, density, sprinkler specifications, and pipe layout are essential.

Fire pumps must be automatic centrifugal types powered by electric motors, diesel engines, or vertical turbine submersible pumps, dedicated solely for firefighting. Pumps should start automatically upon fire detection and stop manually after fire control. For redundancy, electrically driven pumps require diesel engine backups and vice versa, ensuring prime movers are of different types unless supplied by segregated power sources. Engine specifications include endurance, cooling, and adjustable governors to sustain performance.

Sprinkler systems require regular maintenance and testing to ensure functionality. Reservoir levels should be checked weekly, with cleaning every two years. Pumps and engines undergo daily running tests (5 minutes), quarterly lubrication, and annual flow and load tests. Installation valves and alarm devices need weekly inspections and annual overhauls. Sprinklers must be cleaned and flow-tested quarterly, with pressure gauges calibrated annually. Comprehensive maintenance schedules promote system reliability.