Dry Risers…
Dry riser outlets (or landing valves) are connection points on each floor that enable the fire service to attach and advance its hose lines within a building. UK regulations dictate dry risers are compulsory for buildings over 18m but less than 60m tall.
Dry risers are also found in environments where access is limited or compartmentation is problematic (ie hospital corridors and multi-level basements).
The three main components, designed to meet British Standards and Building Approval Regulations, are the external inlet, the piping and the outlet.
The external inlet is sited within an enclosure at ground level. Access to the hose connections is either via key or a window that can be broken for urgent access. All parts should comply with BS5041 in respect of landing valves and BS 336 in respect of fire hose couplings.
Piping
The piping’s diameter is determined by the number of outlets on each floor, as required by British Standards. 100mm for a single outlet, 150mm for more than one outlet. Typically the pipe’s material is made from galvanised steel and it is enclosed within a fire resisting shaft. An air valve is also essential to evacuate the air when it is charged with water.
Outlet
The outlet is also typically fitted within an enclosure in a stairway, protected lobby or cupboard. Each outlet consists of either one or two instantaneous female hose connections, under the control of a gate valve, to allow firefighters to attach their hose and pump water. Again, the connections should meet BS 336 requirements.
Regulated
BS 9990 regulates the design, installation, testing and maintenance of dry risers. It requires a visual inspection to be carried out every six months, with a detailed inspection and servicing carried out annually, which includes a full wet test, as per BS 5306: Part 1 and BS 9990. An outlet is often added on the roof level to allow easy testing and prevent a building’s floor from becoming wet during the test.
