Pneumatic Circuits Chapter 5

Introduction Pneumatic circuit design is the process of selecting the appropriate components and connecting them to perform a certain function. Circuit design is an important aspect in the application of pneumatic equipment. A well designed system will produce a trouble free performance with minimal down time, while a poorly designed system will result in excessive down time and material waste.

Symbology Designing a pneumatic system is not done by one person, but rather done by a several people. For 2 people to communicate it is necessary for them have a common language. This language is a series of symbols which have the same meaning for both people. The NFPA, ANSI, and the ISO have jointly adopted communication standards.

Symbology The symbol used in pneumatic circuit drawings show only the components to be used and how they are inter connected. They do not represent the relative size and position of the components. This means that the symbol for a 2 in. stroke cylinder and a 10 in. stroke cylinder would appear the same.

Basic Symbols Fluid power symbols are generally composed of certain basic symbols. These symbols are combined to represent specific components. The basic symbols are lines, circles, squares, rectangles, diamonds, and several miscellaneous symbols.

Basic Symbols Lines Circles Lines are used to represent flow paths, such as pipe and tubing, mechanical connections, such as shafts and piston rods, and enclosures for multiple components. Circles Circles are used to show energy conversion devices, such as compressors and vacuum pumps, measuring instruments, such as gauges.

Basic Symbols Squares and Rectangles Squares are generally used to represent valves. The number of squares connected together represent the number of valve positions. A single square represents a valve used to control flow or pressure having a number of positions between its extremes. Multiple squares connected together indicates directional control valves having a specific number of distinct operating positions. Rectangles are used to represent linear actuators, such as cylinders.

Basic Symbols Diamonds Functional Symbols Cylinder Symbols Are used to represent conditioning devices, such as filters, water traps, and lubricators. Functional Symbols Are used with basic symbols to describe the action that takes place with in or between the components. Cylinder Symbols Within the rectangle the piston, piston rod, and cushions are shown. Ports are indicated by adding short lines to the outside of the rectangle.

Basic Symbols Single Acting Cylinders