Dry riser: a system of valves and pipe work which enables the fire service to pump water onto upper floors of a building.
Wet riser: a system of valves and pipe work which is kept permanently charged with water, generally utilising pumps and tanks.
Dry risers will be found:
- in buildings over 18 metres above ground level.
- in low level buildings where there are excessive distances from entrances
Wet risers will be found in buildings over 60 metres above ground level.
What does a dry/wet riser look like?
Typical dry/wet risers contain the following components:
- Large vertical pipe of 100mm or 150 metres diameter that can run internally or externally to the building
- Twin/four-way inlet connection at street level boxed in a steel cabinet with glazed door for the dry riser only
- Outlet valves at each landing
- Automatic air release valve at the highest point to provide bleeding of air from the system when it is filled with water
- Pump and tanks for wet risers only