CompTIA Security+ Exam Prep

Answer: C - The preaction system is a sprinkler system that has a thermal-fusible link that must melt before water is released. This system is similar to dry pipe systems in that water is not kept in the pipes, but is released when the pressurized air within the pipes is reduced. Water fills the pipes, but is not released until a thermal-fusible link on the sprinkler head has melted. The goal of combining these two techniques is to give people more time to respond to false alarms or to small fires that can be handled by other means. These systems are usually used only in data-processing environments rather than the whole building due to their costs.