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Wet Riser & Dry Riser System

Wet Riser 

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Wet risers are a legal requirement in buildings over 50m tall as they provide better water pressure on higher floors than dry riser systems can provide. This is a fairly recent requirement, with pre-2006 legislation requiring wet risers only for buildings of 60m or more.

Wet riser systems are very similar to dry riser systems, although, as the name suggests, the pipe networks are kept constantly full through a pressurised supply. This will be in the form of either a storage tank or the mains. The outlet system across the floors remains the same. However, should a fire break out on higher levels, firefighters will have instant access to pressurised water, rather than water that is simply pumped through the system. Wet risers should, at the minimum, provide 1500 litres of water per minute, for a total of 45 minutes.

Dry Riser 

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Dry risers are a legal requirement in buildings more than 18m tall. They’re typically only used in buildings between 18m and 50m, however, due to limitations in how they operate.

Dry riser pipe networks connect a ground floor inlet (usually an external inlet) with multiple internal outlets located across the higher floors of the building. The pipes are typically dry – hence the name. When needed, water is pumped throughout the network, enabling firefighters to attach their equipment to the closest outlet for an instant source of water. Outlets are usually located within every 900 square meters of floor, and are typically found in lobbies, stairways, and cupboards. The pressure limitations of pumped water mean that dry risers perform best in buildings under 50m, while those over 50m require a wet riser system.

The difference between dry & wet risers

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Despite all these similarities, there are some significant differences between the two systems. As a property agent or facilities manager, it’s important to understand how dry & wet riser systems differ.

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Wet Riser & Dry Riser System

This ‘how to’ video has been developed to help property managers understand how to undertake operational checks of Dry Risers or Wet Risers in between the periodic maintenance checks which are completed by your competent contractor.

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How dry riser system works?

In a dry riser system, a dry pipe fire sprinkler system is used in which pipes are filled with compressed air, instead of water. This pressurized air holds a remote valve, known as a dry pipe valve, in a closed position. This dry pipe valve is located in a heated space and it stops water from entering the pipe until fire causes one or more sprinklers to operate. When this happens, the air flees and the dry pipe valve releases, water enters into the pipe, and sprinkles onto the fire to extinguish and prevent it from spreading. For further information regarding dry or wet riser installations and compliance, please contact one of our expert team at Complete Fire and Pumps.

How wet riser system works?

Wet risers are constantly linked to a pressurized water system, fed by ‘fire pumps’ usually located within the basement area of a building. Those fire pumps are also linked to a water tank, these two combined give you your pressure and water supply. So in the event that a fire broke out in your building and an outlet valve was opened the pumps would start and give you the desired pressure and flow

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