Sprinkler, Wet Riser, Pressurized Hydrant Systems
The above fire protection systems will have the following three pump sets: –
- Duty Pumpset
- Standby pumpset
- Jockey pumpset
Firefighting pumpsets draw water from storage tank to feed the sprinkler, wet riser or pressurized hydrant network. Two sets of pumps, one on duty and the other on standby, are provided together with a jockey pump to maintain system pressure. Duty pumpset is normally electric motor driven while the standby pumpset should be supplied with power from the emergency generator if this is available. Otherwise, the standby pumpset should be diesel engine driven. Fuel supply for the diesel engine should be adequate for minimum continuous operation hours. Electrical cabling to supply power to the sprinkler pumps should be of MICC or fire rated type. Batteries for the diesel engine should be maintenance-free type. Jokey pumpset is for maintaining system pressure.
All firefighting pumps should be under positive head, protected from fire and away from locations likely to be flooded.
Pump starter panel should be compartmented for each of the duty, standby and jockey pumps and complete with necessary indicator tights Ventilation slots should be provided with insect screen to prevent entry of vermin. Power supply cables to the panel should be of mineral insulated copper core (MICC) or fire rated type routed within areas with low fire risk. The pump starter panel should be placed within the same room as the fire pumps it controls.
Three pressure switches should be provided at each installation for starting of the sprinkler pumps with the following suggested pressure settings:
- Starting the duty pumpset set at 80% of the system pressure;
- Starting the standby pumpset at 60% of the system pressure; and
- Starting and stopping the jockey pumpset at 90% and 110% of the system pressure respectively
Electrical interlocks should be provided so that the firefighting pumps at each installation should not operate in parallel simultaneously. A buzzer should be sounded should the isolator be in the off or manual position. All firefighting pumpsets should be capable of starting and stopping automatically, except sprinkler pumpset should only be stopped manually by commanding fire officers at site.
Water Storage Tanks
Firefighting water storage tanks may be of pressed steel, fibre reinforced polyester (FRP) or concrete. Pressed steel tanks where used should be hot dipped galvanized and coated internally with bituminous paint for corrosion protection. The water tanks should be compartmented unless they are of reinforced concrete and ball float valves, overflow pipes, drain pipes and water level indicators should be provided for each compartment. The external surface of the tank should be painted red or where this is not desirable, a red band of minimum 200mm should be painted to indicate that this is a fire tank.
The sprinkler tanks not dependent on inflow may be in any location. The sprinkler tank may be combined with hose reel tank in which cases, the tank capacity should be the sum of the water storage for both the sprinkler as well as for the hose reel system. The hose reel tap off level should be above the sprinkler tap off level so that the water reserved for sprinkler system is always maintained