DOE-HDBK-1016/1-93ENGINEERING FLUIDS DIAGRAMS AND PRINTSEngineering Fluid Diagrams and PrintsValveActuatorsSome valves are provided with actuators to allow remote operation, to increase mechanicaladvantage, or both. Figure 2 shows the symbols for the common valve actuators. Note thatalthough each is shown attached to a gate valve, an actuator can be attached to any type of valvebody. If no actuator is shown on a valve symbol, it may be assumed the valve is equipped onlywith a handwheel for manual operation.The combination of a valve and an actuator is commonly called a control valve. Control valvesFigure 2 Valve Actuator Symbolsare symbolized by combining the appropriate valve symbol and actuator symbol, as illustratedin Figure 2. Control valves can be configured in many different ways. The most commonlyfound configurations are to manually control the actuator from a remote operating station, toautomatically control the actuator from an instrument, or both.In many cases, remote control of a valve is accomplishedFigure 3 Remotely Controlled Valveby using an intermediate, small control valve to operatethe actuator of the process control valve. Theintermediate control valve is placed in the line supplyingmotive force to the process control valve, as shown inFigure 3. In this example, air to the process air-operatedcontrol valve is controlled by the solenoid-operated,3-way valve in the air supply line. The 3-way valve maysupply air to the control valve's diaphragm or vent thediaphragm to the atmosphere. PR-02Rev. 0Page 4
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