A Wet Riser is a system of pipe-work and valves which is kept permanently ‘charged’ by a dedicated pump supplying clean water on demand on each floor of a building and is typically used on larger, high rise buildings. The system components must be regularly maintained to prevent leaks, corrosion and loss of adequate pressure. Landing valves that are used as part of a wet riser system are tested to BS 5041-1.
A Dry Riser inlet is permanently connected to an ‘uncharged’ water pipe system that is installed within protected service ‘riser’ shaft within the building, often this is the protected escape staircase enclosures. The inlet breechingof a dry riser system is suitably located within a protective box or ‘cabinet’ for dry riser inlets on the ground floor to enable the fire and rescue service to connect layflat hose to a suitable water supply, allowing water to be pumped from the fire appliance pump up to higher floors or to where there are extensive distances from an entrance. Inlet breechings are tested to BS 5041-3 and the dry riser box for riser inlets are tested to BS 5041-5.
Underground Fire Hydrant
An underground fire hydrant is typically located within a surface box fitted with a cover. Underground fire hydrants and surface box frames and covers are tested to BS 750. The cover of the surface box is often but not always painted in a prominent colour to assist with fast location by fire service personnel. A notice identifying the location of the hydrant is also normally fitted in an adjacent position; in most jurisdictions it is illegal to park a car within a certain distance of a fire hydrant.
Pillar fire hydrants consist of one or more valves and connection outlets in a column shape, which emerges from below ground level, intended primarily to supply water for firefighting and also may be used by water utilities. These hydrants are often provided by the owner/operator of larger developments and the responsibility for the supply of water rests with this organisations responsible person, whilst publicly located hydrants are provided and maintained by the civic authorities. Regular maintenance is required to remove dirt and debris, prevent seizure of the valve, to maintain a clean water supply and to ensure easy removal of the protective cover.
A layflat high pressure hose is attached to the hydrant via a standpipe installed after removal of the surface box cover and the water is delivered by turning a hydrant key which is connected to the hydrant by fire service personnel. The layflat hose connected to the standpipe may be used to supply water directly onto the fire by connecting further lengths of hose and using a branch or nozzle to control the water at the point of delivery. It may also be used to connect the water supply to a fire pump that is transported to the location by the fire service in order to increase the delivered water pressure further. The supply may be split into multiple hoses to distribute the water as required. This water supply can then be connected to a dry riser inlet(s) if required.
For guidance on design and installation of wet and dry riser systems, refer to BS 9990:2006 Code of practice for non-automatic fire fighting systems in buildings. This standard covers good practice in matters affecting the design, installation, testing and maintenance of non-automatic fire fighting systems in buildings. Further information is also available in BS 9999:2008 Code of practice for fire safety in the design, management and use of buildings.
LPCB offers certification of Fire hydrant system components to:-
- BS 5041-1:1987 Fire hydrant systems equipment. Specification for landing valves for wet risers
- BS 5041-3:1975 Fire hydrant systems equipment. Specification for inlet breechings for dry riser inlets
- EN 694:2001 Requirements for Fire-fighting hoses - semi-rigid hoses for fixed systems
- BS 6391:2009 Requirements for non-percolating layflat delivery hoses and hose assemblies for fire fighting purposes.
- BS 5041-5: 1974 Fire hydrant systems equipment. Specification for boxes for foam inlets and dry riser inlets
- BS 750:2006 Specification for underground fire hydrants and surface box frames and covers
- EN 14384:2005 Pillar fire hydrants
- BS 336:2010 Specification for fire hose couplings and ancillary equipment