Dry risers are a building regulations requirement in occupied buildings over 18M tall but can also be found in car parks, multilevel basements or hospital corridors where the fire service access could be limited.
A dry riser system is used by the fire services to distribute water to multiple levels of a building in an emergency. Dry risers are vertical mains fitted into staircase enclosures or other suitable positions, a static pipe with outlet valves on each floor and inlets fitted at ground level to enable the fire and rescue service to connect to the water supply and deliver water to all floors. The current standard for the installation of Dry Riser Systems is BS9990: 2006.
The dry riser external inlets need to be easy accessible by the fire service in an emergency. The dry riser systems pipes are filled with compressed air which is released in an emergency to let water flow through the pipes. The dry riser outlet points are positioned on the upper storeys allowing fire-fighters easy access to water in the event of a fire.
British Standard BS9990:2006 states that dry riser systems should be serviced once every six months with a dry riser annual test including a hydraulic pressure test using a fire service approved hose and pump for a minimum of 15 minutes once every 12 months.
Occupied buildings over 50 metres tall require a wet riser systems. For more information on the difference between a dry riser system and a wet riser system see our knowledge articles.
A dry riser main needs to be ready for use at all times. In order to ensure that it is working properly, it needs to be inspected every six months and subject to a wet pressure test, annually. Testing intervals are laid down in BS9990:2006.
Every 6 months the dry rise installation should be inspected. A check should be made to ensure that fire service access to the inlet box is unobstructed. The inlet box itself together with the non-return valves and drain valve should be checked. All dry riser outlets are inspected to ensure that the valves operate correctly, washers are in place and that any security measures are also in place. The area around each outlet is also checked to ensure that it is free of obstruction. Finally, all necessary signage is checked to ensure that it is in good order and clearly visible. The results should be recorded in a fire log book and any necessary remedial work carried out.
A 6-monthly inspection is carried out, as the first part of an annual wet pressure test. Having carried out the inspection and ensured that all outlets are closed, fire hose is connected to the dry riser inlet. The system is then charged with water pressurised by a fire pump or other testing apparatus, the riser is subject to a pressure of 10 bars for at least 15 minutes: pressures at the inlet and top most outlet are recorded. During this period technicians will inspect all visible pipework, flanges, valves, for leaks, or other defects. On completion of the test the system is drained down, all valves closed and cabinet doors and any other security measures replaced. Depending on the arrangements with the client, any washers may be replaced and any other minor defects made good at the time. The client will then be supplied with a detailed report, noting any further remedial work that may need to be addressed.