Mainly used on large applications where water or gas cannot be used. These tend to be external such as transformers, oil tanks and oil storage silos.
A simple sprinkler open deluge type system with heads spread around the risk. A foam concentrate is mixed with the water to provide the typical expanding agent (the same as with extinguishers).
Will need a large amount of fabrication work to support the pipework, valves and heads.
- Good for external areas.
- Covers large areas.
- Protects flammables liquids – suitable for airports, aircraft hangers, oil storage.
- Foam deluge is a wet agent, so electrical risk needs to be considered.
- Messy – clean up required.
- Same disadvantages as sprinklers for water and pump supplies, although because of the expanding effects of foam sometimes not as much water is required.
- Machine spaces
- Switch rooms
- Generators (local application)
- Fuel stores
- Aircraft hangars
- Storage silos
- Machines/processes that are outdoors