In a building, a fire hydrant system is a safety measure or emergency equipment required in some buildings that comprises a series of components that when assembled together provide a source of water to assist fire authorities in a fire. A fire hydrant system is a water supply with a sufficient pressure and flow delivered through pipes throughout a building to strategically located network of valves for fire-fighting purposes.
In some circumstances, water from a reticulated fire hydrant system can also be shared with other safety measures such as automatic fire sprinkler systems or fire hose reels. Under normal circumstances, a fire hydrant system is pressurized with water ready for emergency use. When a hydrant valve is opened, the system experiences a drop in water pressure.
The drop in water pressure is detected by a pressure switch which in turn starts the booster pump(s), drawing water from the water supply to increase the water pressure of the system.
Water from the hydrant is then directed through the lay flat fire hose to a nozzle which is then directed to the seat of a fire. During a fire the fire brigade may provide additional water and boost the water pressure to satisfy the demands of the fire hydrant system. This is carried out by connecting a fire appliance (truck) between an alternate water supply and the booster connection.