What type of system uses pressurized air to move water in fire sprinkler systems?

The dry pipe sprinkler system is designed to use pressurized air to control the flow of water within the pipes. In this system, the pipes are filled with compressed air rather than water. Upon the activation of a sprinkler head due to heat from a fire, the air pressure in the pipes drops, allowing the dry pipe valve to open. This then releases water from a storage tank or other source into the system and ultimately to the individual sprinkler heads.

This design is particularly advantageous in environments where the risk of freezing exists, as it prevents water from being in the pipes during colder temperatures. By only releasing water when there is an emergency, the dry pipe system helps to manage the risk associated with frozen pipes, making it suitable for unheated or outdoor areas.

The other types of systems mentioned operate differently. For instance, wet pipe systems contain water within the pipes at all times, pre-action systems incorporate both dry and wet pipe principles, and deluge systems release water through multiple open heads simultaneously without the use of a pressurized air mechanism. Thus, the distinctive feature of using pressurized air to control water flow firmly identifies the dry pipe sprinkler system as the correct answer.