The Trerice “Self-Op” Temperature Regulator is a fully self-contained unit, requiring no external power source (i.e., compressed air or electricity). Regulation 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.
The actuator consists of the following assemblies: housing, bellows and spring return, and thermal system. Three actuator models are available:
• Model 91000 is non-indicating and direct acting.
• Model 91400 is equipped with an integral dial thermometer to indicate sensing bulb temperature and is direct acting.
• Model 91600 (Fail-Safe) is non-indicating and direct acting. It is specifically designed to cause the valve to move to the cooler position in case of thermal system failure.

Sterlco's R-150-F (cooling) and 150-F (heating) valves have high engineering standards and energy saving features. Simple yet efficient design requires minimum maintenance; heavy-duty construction assures long valve life. Valves are temperature actuated, self powered, fully balanced and applicable to heating or cooling processes using water, oil, steam or other fluids.