Hydraulic and pneumatic accessories

Publisher Summary A hydraulic system is closed, and the oil used is stored in a tank or reservoir to which it is returned after use. Although, probably the most mundane part of the system, the design and maintenance of the reservoir are of paramount importance for reliable operation. The reliability of a hydraulic system is strongly influenced by the state of fluid. Contamination from dirt or the products of oxidation and deterioration of a fluid's lubrication ability will lead to rapid wear and failure. The various end devices in a pneumatic system are linked to the air receiver by pipes, tubes, or hoses. In many schemes the air supply is installed as a fixed service, similar in principle, to an electrical ring main allowing future devices to be added as required. Generally, distribution is arranged as a manifold or as a ring main. With strategically placed isolation valves, a ring main has the advantage that parts of the ring can be isolated for maintenance, modification, or repair without affecting the rest of the system. Pneumatic systems are vulnerable to moisture and, to provide drainage, the piping should be installed with a slope of about 1% (1 in 100) down from the reservoir. A water trap fitted at the lowest point of the system allows condensation to be run off, and all tap-offs are taken from the top of the pipe to prevent water collecting in branch lines.