What type of switch uses a paddle or flipper to detect airflow?

The sail switch, which is correctly identified as the answer, is specifically designed to detect the presence and direction of airflow. It features a paddle or flipper that moves when air passes over it. This movement then activates or deactivates an electrical circuit, signaling whether there is adequate airflow for proper operation of HVACR systems. Sail switches are commonly used for safety purposes, ensuring that the system only operates when there is sufficient airflow to prevent conditions that may lead to overheating or other system failures.

In contrast, an airflow sensor measures the velocity or volume of air, but it does not utilize a paddle mechanism like the sail switch. Pressure switches, on the other hand, monitor changes in air pressure rather than direct airflow. Flow meters measure the quantity of fluid passing through a system but do not operate on the principle of a paddle movement. Thus, the sail switch is the most accurate response because of its specific design and function that directly involves detecting airflow through physical movement of a paddle.