Wet Riser Pipes

A well-designed wet riser/hydrant systems is the backbone of fire protection systems for modern buildings and is mandated by the local Fire Brigade, insurance authorities and other regulatory bodies. A typical building normally has two or more shafts, which travel from the lowest level of the building to its terrace. Such shafts are normally used to carry the piping for the wet-riser systems. Hydrant outlets are provided on every floor so that the entire floor area of the building is adequately covered. Outlets are provided in the form of double-outlet landing valves. Apart from a canvas hose for the use of fire-fighting personnel in the event of fire, a rubber hose of 20 mm diameter is also provided, mounted on a hose-reel drum to enable volunteers from the general public to help fight incipient fires.All wet-riser pipes remain charged with water at systems pressure. The opening of a hydrant landing valve or hose reel on any floor reduces the pressure in the pipeline and starts the hydrant pump. Pump-sets of suitable capacity are provided for this purpose. Because of the static pressure differential caused by the change in floor height, a multi-stage pump is employed so that different tapping can be taken from the output of the pump. Each of these tapping can be used to serve more than one floor. Pumps-sets should be fed with reliable electric supply from a separate feeder and it is therefore also desirable to have a stand-by diesel pump. Apart from the wet riser system, hydrant points should also be provided at strategic locations around the building at ground level.Water must be made available through reservoirs in adequate quantities at convenient locations. Periodic drills should be conducted by opening the hydrant valves to ensure proper operation of the systems.