Which type of fire suppression system must be opened and tested manually?

The correct answer is the type of fire suppression system that requires manual opening and testing as part of its functionality. In the case of dry pipe systems, they are designed to hold water in a remote supply until a fire condition is detected. When a fire occurs, a heat-sensitive device must trigger the valves, allowing the compressed air to escape and water to flow through the pipes to the sprinklers. However, the testing of these systems often involves manual operation to ensure the valves and mechanisms function properly, verifying that the system will activate in a real emergency.

Additionally, dry pipe systems are specifically adaptable for environments where pipes might freeze, as they maintain air pressure within the pipes. This necessitates routine checks and manual testing protocols to guarantee their operational readiness, making manual intervention a key aspect of maintaining this type of system. Other fire suppression systems listed typically involve automatic processes for activation and testing, which makes the dry pipe system uniquely reliant on manual opening and testing procedures.