The Pneumatic World

One of the most common engineering components you will find at work today is the pneumatic actuator. A pneumatic actuator is simply an object that converts energy into motion. The most common type of pneumatic actuator is compressed air. Pneumatic actuators are found in almost every industrial environment, from waste management and reclamation centers to oil refineries and multiple types of plants that deal in chemical or industrial manufacturing. Pneumatic actuators are composed of a variety of materials from steel to plastic, and are primarily composed of a piston with a diaphragm, cylinder, and pneumatic valves. The diaphragm covers the piston holding the air in the upper half of the cylinder, once compressed the diaphragm forces the air downward turning the piston and forcing which in turn moves the valve stem. Because of the design it is very easy to generate a great deal of torque or pressure with a very low level of initial force, making pneumatic actuators ideal valve devices in a number of applications.

The idea of forcing air flow to operated machinery is not a new idea. Because of its abundance, harmlessness, and lack of cost (air is free – unless we’re speaking of a hypothetical planet in a galaxy far away named Spaceball, in which case air comes canned and at a high price) air is the perfect material for generating energy. Wind has been captured and converted into a clean renewable energy source for thousands of years through the use of windmills and wind turbines.

The first known pneumatic devices created by man are most likely bellows. A bellow is a device similar to a giant enclosed fan that was used by blacksmiths to add air into their ovens in order to heat the fire to tremendous levels capable of melting metals such as iron or steel. A bellow was composed of a two wooden oars connected together at one end by a hinge to form a v shape. Holes were cut into one of the boards to allow air flow, after which a flap was attached limiting the direction of the air flow to one direction. The wooden frame was then draped with a cloth or leather material to form a bag to capture air, and a nozzle was often affixed to the end. The result was a device which could force air through a hole in the blacksmiths oven to generate the heat required for working with metals. Bellows allowed blacksmiths to raise oven temperatures to over 2,800 degrees.

Modern pneumatic devices are far superior to ancient bellows. However, there are a few potential drawbacks to the use of pneumatic devices. As air is compressed it’s dew point rises creating excess moisture within the lines and pipes it travels, potentially resulting in corrosion or even freezing and bursting. Therefore, to limit the potential for damage a compressed air dryer is often incorporated into the system. Compressed air dyers work exactly as they sound, eliminating water vapors from the compressed air and essentially drying out the system. This action helps avoid major catastrophe from excess moisture and water vapor.

For as long as man has been attempting to harness the power of air, so have we focused on controlling the power of water. The concept of hydraulics has been around for ages. The first known masters of hydraulics were the ancient Greeks who used water the generate power for a variety of machines and devices. Later the Romans became possibly the most widely known hydraulic engineers with their complex system of aqueducts which still stand today.