Hydrant System Essential

The fire hydrant system is the backbone of the fire fighting systems in a building or premises. The system is a water distribution system consisting of water tank, suction piping, fire pumps and a distributed piping system. The distributed piping system establishes connectivity throughout the building through fire hydrants, hoses and nozzles. The purpose of the fire hydrant system is to provide a readily available source of water to any point throughout the building. This helps in controlling fire during an emergency.

Water Supply

Water for the hydrant service is stored in easily accessible surface underground-lined reservoir or above ground steel, concrete, or masonry tanks. The effective capacity of the reservoir differs for various clauses of occupancies and sizes of hydrant installations. The effective capacity should be above the foot valve seat in case of negative suction and above the level of the top of pump casing in case of positive suction. The reservoir will exclusively be reserved for hydrant service only.
 
Electric Supply 

The electric supply to the pumping sets is entirely independent of all other equipments in the premises. This means that, even when the power throughout the entire premises is switched off, uninterrupted power supply would be available. This is implemented by connecting the pumps directly to the incoming side of the main L.T. Breaker.

Working of System

Manual Mode

In Manual mode, the Jockey Pump or Main pump is operated manually. Jockey pump normally maintains the 7Kg. Pressure in Hydrant Header pipe in wet system and Main Pump can be operated during the emergency in the event of a fire.
 
In Auto Control mode, Jockey pump starts automatically whenever the Hydrant header pressure drop below 4 Kg and stops automatically at 7 Kg/cm2. Jockey pump maintains the pressure in the header pipe line. Operations of Jockey pump depend on the leakage/air in the pipe line.
 
The Main pump automatically starts when pressure drops below 4 Kg/cm2 and supplies the water with the flow of 137 m3/hr and pressure of 7 Kg/cm2. Main Pump has to be stopped manually. Trained personnel should attend the pump house immediately on operation of Main pump to monitor the water tank supply level, malfunctioning or emergency requirement of Pump operation.
 
Automatic System

The ring main and wet riser, are generally charged with water at a pressure of 7kgs/sq.m. If there is any pressure loss due to minor leakage in the pipeline or due to evaporation, the jockey pump would be set at a specific pressure. This pressure operates and maintains the required pressure in the pipeline. On operation of one or more hydrant points, pressure is reduced. This fall in pressure actuates the pressure switch set at a particular set point lower than the jockey pump. The pressure switch sends the control signal to the motor switchgear, which brings the motor driven pump into operation, thus replenishing the loss of pressure.
 
In case if the motor driven pump does not come into operation due to power failure or other malfunction, pressure in the line further fall down, actuating a second pressure in the line and thereby actuating a second pressure switch set at a further lower set level. This automatically makes the standby diesel engine pump to operate, supplying water to the system. Invariably, switching off of both the pumps is done manually.
 
The unlined flex canvas hoses and allied equipments are housed in a metal chamber and are located around the buildings with metal frame glass shutters. These equipments are also housed inside the high risk building near the internal Hydrant Valves.