Services

Fire Extinguishers

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Fire Risk Assessments

Services - Dry and Wet Riser

What are dry and wet risers systems used for?
Dry/wet risers are intended for the use of the Fire Service to provide a readily available means of delivering considerable quantities of water to extinguish or to prevent the spread of fire. If your fire risk assessment concludes that you may need the intervention of the Fire Service to fight a fire, you must ensure that your riser systems or hydrants are working properly.

Before installation of dry or wet rising mains, the local Authority and Fire Officer must be consulted to ascertain their exact requirements.

What is the difference between dry riser and wet riser? (Dry/wet risers are often called Rising Mains)

Dry riser: system of valves and pipework which enables the Fire Service to pump water on to upper floors of a building.

Wet riser: system of valves and pipework which are kept permanently charged with water.

Where do we find dry/wet risers?
Dry risers will be found:
• in buildings over 18 metres above ground level.
• in low level buildings where there are excessive distances from entrances (60m)
Wet risers will be found in buildings over 60 metres above ground level.

What does a dry/wet riser system look like?

Typical dry/wet risers contain the following components:
• large vertical pipe of 100 mm diameter that can run internally or externally to the building
• twin inlet connection at street level boxed in a steel cabinet with glazed door for dry riser only
• outlet valves at each landing
• automatic air release valve at the highest point to provide automatic bleeding of air from the system when it is filled with water
• pump for wet riser only Why do dry/wet risers need to be serviced?
• risers are prone to neglect and vandalism
• severe penalties should the rising main fail to work for the Fire Service
• leaking from a wet riser could cause substantial damage

*BS 9990 2006 recommends for dry risers:
• a service every six months
• an annual pressure test

*BS 9990 2006 recommends for wet risers:
• 2 service visits per year
• 2 electric pump inspection service visits per year
• 1 flow test per year (if applicable)