Which unit houses the pinwheel rotor in the airflow system?

• A. Indicating and control panel
• B. Pinwheel sensor unit
• C. Airflow remote alarm unit
• D. Filter module

Answer: (B)

The pinwheel rotor is housed in the pinwheel sensor unit. The rotor is the spinning element that responds to airflow, and it needs to be in a housing with the sensor electronics so its rotational speed can be read and converted into an electrical signal. That signal is then sent to the indicating and control panel for display and monitoring. The other units serve different roles—display/control, alarm monitoring, or filtration—so they don’t contain the rotor itself.