Valve Actuators

DOE-HDBK-1016/1-93 ENGINEERING FLUIDS DIAGRAMS AND PRINTS Engineering Fluid Diagrams and Prints Valve Actuators Some valves are provided with actuators to allow remote operation, to increase mechanical advantage, or both. Figure 2 shows the symbols for the common valve actuators. Note that although each is shown attached to a gate valve, an actuator can be attached to any type of valve body. If no actuator is shown on a valve symbol, it may be assumed the valve is equipped only with a handwheel for manual operation. The combination of a valve and an actuator is commonly called a control valve. Control valves Figure 2 Valve Actuator Symbols are symbolized by combining the appropriate valve symbol and actuator symbol, as illustrated in Figure 2. Control valves can be configured in many different ways. The most commonly found configurations are to manually control the actuator from a remote operating station, to automatically control the actuator from an instrument, or both. In many cases, remote control of a valve is accomplished Figure 3 Remotely Controlled Valve by using an intermediate, small control valve to operate the actuator of the process control valve. The intermediate control valve is placed in the line supplying motive force to the process control valve, as shown in Figure 3. In this example, air to the process air-operated control valve is controlled by the solenoid-operated, 3-way valve in the air supply line. The 3-way valve may supply air to the control valve's diaphragm or vent the diaphragm to the atmosphere. PR-02 Rev. 0 Page 4