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#067 Pneumatic Circuits and Control Technique Basics : Basic Pneumatic Circuits

Category : Pneumatic Drives
February25, 2011

Pneumatic circuits and control technique basics are explained based on a scenario of a factory using LCA. In the #066, an outline of Clean Air Systems was discussed. Explained in this volume are the devices placed downstream to the Clean Air System such as air control devices including directional valves and velocity control valves, as well as JIS standard symbols signifying pneumatic actuators (air cylinders, etc.).

(1) Basic Pneumatic Circuit

A typical pneumatic device system is shown in [Fig.1].

[Fig.1] Typical Pneumatic Device System

The Clean Air System explained in #066 corresponds to the Air Quality Control Devices section in [Fig.1] above. The compressed air generation devices are located upstream to the Air Quality Control section, and the flow control devices and actuators are placed downstream of the Air Quality Control section.
The air pressure generally used is 7kgf/cm2 or less. The compressed air is cleaned of oil, water, and stored in the air tank, then further cleaned by the FRL unit, and supplied to the air cylinder through a regulator (pressure adjustment valve).
The system portion from the compressed air generator to the air quality control section is similar to water service supply system. The waterline pressure is equivalent to air pressure. The LCA are driven by pressured air derived from the air quality control section which is analogous to a water faucet.

(2) Symbol Description of Basic Air Circuits

The system in the [Fig.1] is described a compressed air circuit diagram using the symbols defined by "JIS0125 Graphic symbols and circuit diagrams". [Fig.2] below is a graphical symbol representation of the [Fig.1].

[Fig. 2] Symbol Representation of [Fig.1] Diagram

From the figures [Fig.1] and [Fig.2], it can be observed that easily and accurately describing compressed air device systems is possible by mastering the basics of compressed air symbols and air circuit diagram drawings. Please refer to JIS standards documentation, etc. to become familiar with the compressed air system symbols.