Overall advantages of compressed airThe use of compressed air in low cost automation using simple pneumatic cylinders and valves is widespread. It is possible to introduce quite sophisticated logic using air as both the control medium and the power medium. The connections are simply made with nylon tube, so it is easy to experiment on different circuits with a minimum of fuss, in a way that would not be possible with another medium. Pneumatic logic circuits today make widespread use of manifolds and sub-bases, which make for compact connections and reliability. This is discussed elsewhere in the text. Compressed air easily lends itself to central generation; the transmission pipes are simple to install, being made of steel, copper, aluminium or ABS. There are other uses for air, for which no other medium would be acceptable – for pneumatic conveying, for aeration, for paint spraying, for blast-cleaning and many other commercial processes. As well as forming an indispensable part of a factory layout, it is also widely used on contractors sites and in mines and quarries. For operating a range of equipment from small tools like road breakers, rock and concrete drills and sump pumps up to large track mounted quarry drills it has unparalleled advantages. Although for powering high performance rock drills it has to some extent been superseded by hydraulic power, it will still form a major energy source for the future. There is a natural tendency, when first making a choice of a compressor to run an installation, to go to some trouble to obtain the most efficient one on the market. Compressor manufacturers spend much of their development effort in seeking a few extra percent improvement in efficiency, which is an obviously desirable aim. But very often the extra efficiency in the generation of the air is not matched by a similar effort put in to economising its transmission and use. It will be found that good housekeeping of the transmission system and proper use and maintenance of equipment will be amply repaid in fuel savings. The remaining chapters of this section will deal in some detail with the matters touched on above.