• Pipes are not filled with water
• All sprinkler heads are of the standard type (they are closed),
• A detection device opens a water valve
• Water fills the pipes
• Water only flows from a sprinkler head if it is opened by heat from a fire,
• Water flows until shut off and system is reset
• Used primarily to protect property where water could severely damage facilities or equipment, (historical items)

Pipes in protected area are empty; a detector signal triggers the system, allowing water to enter pipes and flow into piping network; heat from a fire may then open a sprinkler head; accidental damage to a head will not result in water flow