Air Compressors and Civilization
An air compressor is a mechanical device that takes in air at atmospheric pressure, compresses it, and delivers it at a higher pressure. Given this definition, it can be said that the first air compressors are bellows. Bellows are basically a collapsible container with an air inlet port which opens when the container is expanded, and closes when it is collapsed, using a system of valves and flaps. The air is compressed as the container is collapsed, and is forced out through another opening, often a nozzle. Of course, the pressure of the compressed air is far below those produced by modern compressors but the principle is the same.
Bellows have been used by the Ancient Egyptians and Chinese as well as later Asians, particularly the Japanese, and Europeans. Among these peoples, bellows were used primarily in furnaces. Compressed air injected into the furnace increases the rate of combustion, thus producing more heat. It was this level of heat that enabled ancient craftsmen to smelt and weld metallurgical iron.
With this capability, blacksmiths were able to produce plows, spades, pickaxes, and machetes to better farm the fields; jewelry and ornaments made of gold, silver, or bronze for beautification; as well as swords, spears, and shields of the soldiers who then conquered other lands, imposing their own culture and civilization on the subdued, or at least, influencing them.
It was this same capability that eventually led to the production of modern air compressors. It took a few hundred years to move from the muscle-powered bellows to the electric or gas compressors. During the Industrial Revolution, steam-powered engines were used to power air compressors. These were used to provide air to underwater diving gear, which allowed marine scientists to study the ocean floor and engineers to construct underwater posts for bridges. By this time, pneumatic rock drills have been invented and it was the steam compressors that powered them, greatly increasing the production of useful and precious metals and stones.
The invention of the internal combustion engine further improved the design of the air compressor. Apart from providing power to the compressor, its design has also been adopted for compressing air. When a piston of the engine travels downward, it draws in air from outside. In the combustion engine, the purpose is to mix the air with fuel for better combustion, but in an air compressor, the fuel and spark plug are removed. At the upstroke of the piston, air is compressed and channeled to a tank for storage. This uses the same valves and flaps that bellows use.
In addition to piston-type compressors, there are now rotary, vane, and centrifugal types. All of them, however, started with the ancient bellows.