Description of compressed air and pneumatic control systems

Compressed air is used in many operations and processes and as a source of energy for heating, ventilating and air conditioning (HVAC) and process actuators and motors. It is also use as low-pressure systems and for pneumatic control. Air can be compressed in several different ways and supplied at varying pressures and degrees of filtration depending on its use. Paragraph 6-3, General compressed air equipment description and operation, explains the operation of various types of compressors and dryers.

1. Compressed air system. A typical compressed air system is shown in figure 6- 1, Schematic of a typical compressed air system. The system is capable of producing instrument quality air for pneumatic HVAC controls, tools, conveying systems and general plant air. The system consists of a single motor driven single stage rotary screw compressor with inlet air filter, a safety relief valve, aftercooler, air/oil separator, air receiver with safety relief valve, prefilter, air dryer, afterfilter, oil/water traps and oil/water separator.
2. Pneumatic control system. For a description of a pneumatic control system refer to chapter 4, Heating, ventilating, and air-conditioning (HVAC) equipment and controls, paragraph 4-1, Description of HVAC systems.
3. Compressed air and pneumatic control systems. More information on design, maintenance, and testing of compressed air systems is found in the American Society of Mechanical Engineers (ASME): B19.1 Safety standard for air compressor systems, B31.1 Power piping, and Chapter 8. Boiler and pressure vessels.