Foam deluge systems, sprinkler heads are open and the pipe is not pressurized with air. Foam Deluge systems are connected to a water supply through a deluge valve that is opened by the operation of a smoke or heat detection system. Foam is mixed in with the water supply from a foam bladder tank. The detection system is installed in the same area as the sprinklers. When the detection system is activated foam water discharges through all of the sprinkler heads in the system. Foam Deluge systems are used in places that are considered high hazard areas such as power plants, off shore oil rigs, aircraft hangars and chemical storage or processing facilities.

A sample of foam deluge system installation is shown as below.