Some valves are provided with actuators to allow remote operation, to increase mechanical advantage, or both.įigure 2 shows the symbols for the common valve actuators. In such cases, information concerning the valve type may be conveyed by the component identification number or by the notes and legend section of the drawing however, in many instances even that may not hold true.
It should be noted that globe and gate valves will often be depicted by the same valve symbol. Figure 1 shows the symbols that depict the major valve types. Valves are used to control the direction, flow rate, and pressure of fluids. To read and understand engineering fluid diagrams and prints, usually referred to as P&IDs, an individual must be familiar with the basic symbols.
