As the complexity of pneumatic control systems grows, so it becomes more important to ensure high levels of reliability and integrity. However, not every system requires a huge valve island or bus communication to achieve the required level of automation. Neil Saunders looks at the common components and processes involved, from the most basic design to a complete production line. Pneumatic control has been in use for many years, especially in the pharmaceutical and food and beverage industries where hygienic conditions must be maintained to a very high standard. Pneumatics have many advantages, including a simplicity of design, low maintenance requirements and excellent reliability due in part to the use of compressed air as the power source, which is effectively inert and readily available. In addition, these systems are intrinsically safe and so can also be used in hazardous atmospheres, such as those in the petro-chemical industries. Modern control systems can be divided into two groups, centralised and decentralised. As the names suggest the main control functions will either be grouped at a central point or located at the point of control, such as a process control valve. A centralised control solution is the more traditional solution and will usually involve a control panel containing a bank of control solenoids which are connected to the process control valves using air lines alone.
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