Traditionally pneumatics and hydraulics are thought to be a mechanical engineer’s subject. In practice the techniques tend to be more akin to the ideas used in electronics and process control. This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatic systems. It is intended for engineers and technicians who wish to have an insight into the components and operation of a pneumatics or hydraulic system. The mathematical content has been deliberately kept simple with the aim of making the book readable rather than rigorous.