What Is a Thermal Actuator?

Actuators are merely devices used to convert energy into motion. A thermal actuator is a type of non-electric motor containing components such as a piston and a thermal sensitive material capable of producing linear motion in response to temperature changes. These devices can be used for many applications; the aerospace, automotive, agricultural industries all widely employ thermal actuator devices.

A thermal actuator is one of the few devices that require no outside power source to produce motion. In a thermal actuator system, temperature changes can be used to perform certain tasks such as release latches, operate switches and open or close valves. These devices are very sensitive and can be used for applications that require actuation even at very slight temperature changes.

The thermal-sensitive materials used in a thermal actuator react to fluctuations in temperature, causing the actuator's piston component to move. These materials are engineered to expand as temperatures rise, driving a piston out of the actuator. When a thermal actuator is exposed to decreases in temperature, the thermal-sensitive materials inside contract, allowing the device's piston to retract.

Stroke refers to the distance a piston travels outward from an actuator. Many of the more common thermal actuators feature pistons that can extend between 0.015 inches (0.381 millimeters) and 0.500 inches (12.7 millimeters). Most thermal actuators are made to react to temperatures anywhere between 86 degrees Fahrenheit (30 degrees Celsius) and 572 degrees Fahrenheit (300 degrees Celsius).

Manufacturers produce thermal actuators in a wide range of sizes and configurations, making them ideal for many different applications. Many thermal actuators are designed for use in pressurized or vacuum, gas, or liquid environments. They can be constructed out of durable, rugged materials such as brass, aluminum or stainless steel and feature custom mounting configurations. Thermal actuators are easily machined and can be designed to feature any thread type or valve end. A well-constructed thermal actuator is resistant to shock and vibration.

In the aerospace industry, thermal actuators are used in safety shut-off devices, fuel temperature control and engine lubrication systems. This type of actuator is often used in the agricultural industry in livestock watering systems for freeze protection and in automatic greenhouse ventilation systems. The automotive industry utilizes thermal actuators in transmission cooler, thermostat and oil temperature regulation applications.