Definition - What does Temperature Regulator mean?
A Temperature Regulator is an instrument which is used to provide reliable temperature control without the need of an external power source (i.e., compressed air or electricity). Temperature regulators are self operating devices. They are also mechanically operated devices which are designed to regulate system temperature by modulating the flow of a heating or cooling fluid in response to temperature changes.
Petropedia explains Temperature Regulator
Regulation in a temperature regulator takes place when the sensing element (bulb) of the thermal system is exposed to changes in temperature. The thermal system is charged with a predetermined amount of vapor fill which when heated will cause a bellows within the unit’s actuator housing to expand. As the bellows expands, it compresses a return spring while simultaneously moving the valve stem downward to stroke the valve. When the process temperature decreases (or in the event of thermal system failure), the return spring will move the valve stem upward to the “out” position. The choice of valve action (stem In-To-Close or stem In-To-Open) will determine its system failure position.