Dry Riser System Explained
When fires happen in tall buildings, the speed in which firefighters can apply pressurised water as close to the fire as possible determine the number of lives saved and how property damage is minimised. With a dry riser system, firefighters are able to combat fires in each level of a building without the need to drag long and heavy fire hoses through several floors. This fixed water distribution system brings water to multiple levels, making it easier and faster to discharge fire fighting operations at each level where a fire is happening.
Legally required for buildings that are more than 18 metres high, dry riser systems are recommended as well in buildings where water pressure is not enough for fire suppression and in unheated structures where pipes may freeze.
Dry Riser System Components
Empty when not in use, dry risers are only filled with water during testing or an actual fire. The system consists of an inlet, pipes, and outlet points.
Typically located at the ground floor or in fire escape areas for easy access for the fire and rescue service, the dry riser inlet is housed in a labelled cabinet with a breakable glass front. The inlet is ideally positioned close to the rising main for best water pressure, allowing water to be pumped as quickly as possible to the valves on the upper floors.
As mentioned, a dry riser system’s piping does not contain water when not in use. The pipes are made of galvanised steel and the vertical piping traverses the entire height of the building. At the top, an air valve is installed to allow the release of air when the pipes are being filled with water. The diameter of the pipes are dependent on the particular building’s requirements as prescribed under the British Standards.
The outlet points within the building – usually referred to as Landing Outlets or Landing Valves – are found on each level. Similar to the inlet, these are housed inside labelled cabinets with a breakable front. The outlet cabinets are normally installed within a floor’s fire-protected spaces such as the fire escape areas or staircases.
How they work: Dry riser system in action
In the event of a fire, firefighters connect a pump and hose to the inlet, charging the dry riser system with water from the fire engine. (Water supply from the fire engine is augmented with water from the closest fire hydrant.) They then take another hose and connect it to the outlet point nearest the fire, which is then opened to charge this hose with water from the vertical dry riser pipe, enabling them to suppress the fire. The pump at the inlet ensures the steady flow and pressure of water during the entire fire fighting operation.
As this system eliminates the need to drag long hoses up the stairs though a building, the amount of time needed to bring pressurised water to the fire’s location is reduced. This also clears the stairwells for faster evacuation of the building’s occupants.
Here is an informative short video from the Leicestershire Fire and Rescue Service Official Channel about the basics of a dry riser system.
Dry risers are an integral part of a building’s fire strategy. If you have any inquiries on fire stopping surveys and want to ensure your compliance, don’t hesitate to send us an email or give us a call.