In temperature control, which components typically act as actuators?

• A. Heating element and steam control valve
• B. Thermocouple and RTD
• C. Orifice plate and magnetic flow meter
• D. Pressure transducer

Answer: (A)

In temperature control, actuators are devices that take the controller’s signal and convert it into a physical change in the process, specifically by adjusting heat input. The heating element and steam control valve do exactly this: the heating element adds heat when powered, and the steam control valve modulates steam flow to change how much heat is delivered. That direct ability to influence the process temperature makes them actuators.

The other devices are sensors or flow/pressure instruments. Thermocouples and RTDs measure temperature and feed that information to the controller; they don’t change the process. An orifice plate and a magnetic flow meter relate to flow, not heating. A pressure transducer measures pressure. None of these act to modulate heat input in a temperature control loop.