What is a characteristic of spring-loaded diaphragm actuators?

A spring-loaded diaphragm actuator is designed to convert pressure signals into mechanical movement. This type of actuator incorporates a diaphragm, which is a flexible membrane, along with a diaphragm plate and an actuator stem. The diaphragm is vital for controlling the movement and ultimately drives the actuator's response to changes in pressure.

In this configuration, when pressure is applied, it causes the diaphragm to flex. This movement is transmitted through the diaphragm plate to the actuator stem, which then activates the controlled device, such as a valve. The integration of both the diaphragm and the diaphragm plate is crucial because it allows for the appropriate mechanical advantage and precise control of positioning in various applications.

The other possible options do not accurately describe the structure or functioning of spring-loaded diaphragm actuators. They often require a diaphragm and diaphragm plate for proper operation, they are not limited to non-return applications, and while they operate without the need for an external power source, this characteristic alone does not define their structure and functionality. Therefore, the answer that includes the diaphragm and diaphragm plate connected to an actuator stem provides the correct understanding of the actuator's components.