Any building's dry risers are vulnerable to neglect, corrosion and vandalism. That's why it's crucial to get your dry risers inspected and pressure-tested on a regular basis to make sure they'll work when you need them to.
Dry riser systems comprise vertical mains which are normally fitted into staircase enclosures with outlet valves on each floor ready to deliver a supply of water to fire fighting hoses. An external inlet valve at ground level enables connection with a water supply, normally from a fire appliance.
These systems are normally installed in buildings which are more than 18m high, although if a building has more than 18 storeys, then a wet riser (which is permanently charged with water) will be installed.
The new code of practice recommends that a full visual check is made every six months with a full test at pressure every 12 months. In a fire situation, the riser will be pressurised to 10 bar immediately so it is crucial that all inlet and landing valves and associated washers are sound and the riser itself is clear of debris.
The new document, BS 9990, brings up to date the guidance on dry and wet fire mains, or risers, which was previously covered by BS 5306, Part 1. The principal changes from BS 5306 are that the new standard no longer gives guidance on when and where such systems are needed, as this is now given in guidance supporting the building regulations.
The new code deals solely with design, provision, sitting, installation and maintenance. Guidance on hose reels and foam inlets remains in the revised BS 5306, Part 1.
During the 12 month test, the code recommends that initially the top valve of the system should be opened and the system flushed out to remove any debris; in public car parks, the debris is often discarded syringes. The system should then be charged and held at its design operating pressure (normally 10 bar) for 15 minutes whilst the pressure and all valves are monitored. The code also states that this maintenance procedure should only be carried out by a competent person.