Which of the following devices is used to measure air pressure in dry pipe systems?

The air pressure gauge is specifically designed to measure air pressure in dry pipe sprinkler systems. These systems rely on pressurized air to keep the water in the pipes from flowing until the system is activated during a fire. The air pressure must be maintained at a specific level to ensure that the dry pipe valve functions correctly and allows for water to flow into the system when needed.

Using an air pressure gauge ensures that the pressure remains within the operational limits, which is critical for the reliable performance of the fire protection system. If the air pressure drops too low, it may result in a failure to activate the system when required. Conversely, excessive pressure can also be a concern as it can stress the pipe infrastructure.

The other devices mentioned do not serve the purpose of measuring air pressure in dry pipe systems. A temperature gauge measures temperature, which is not relevant to the pressure component of dry pipe systems. A water flow indicator tracks the flow of water but does not measure air pressure. An electrical meter is used for measuring electrical parameters and has no relation to air pressure in fire protection systems. This distinction highlights the importance of the air pressure gauge in ensuring the proper function and safety of dry pipe sprinkler systems.