Popular media tells us that most encounters with vacuum environments (hello, outer space) end in explosive deaths or an eternal drifting about in the cold embrace of the great unknown. In real life, very few of us — in this lifetime, at least — will ever get the chance to put ourselves in the middle of perilous space adventures. In fact, NASA has to construct massive vacuum chambers in order to replicate deep space environment and test hardware that will be sent to where no living human being has ever gone before. However, the practical uses of vacuum chambers are far from confined in the realm of movies or space travel.
A vacuum is typically defined as a space void of matter, but the term also encompasses regions where the gaseous pressure is lower than the atmospheric pressure. The lower the gas pressure is inside a vacuum chamber, the closer it approaches a perfect vacuum. The closest thing that we have to a perfect vacuum is outer space, which has an average of a few hydrogen atoms per cubic meter. Those available on Earth are as follows:
- Extremely high vacuum – requires the removal of trace gases
- Ultra-high vacuum – common in engineering, physics, and chemistry
- High vacuum – requires ion gauge measurements and multiple pumping
- Medium vacuum – can be achieved with a single pump
- Low vacuum – examples include the common vacuum cleaner
- Atmospheric pressure
Uses and Applications
Aside from vacuum cleaners, many everyday conveniences are made possible by understanding how vacuum works and how it can be used to our advantage. Some of the everyday practical applications of vacuums are as follows:
Vacuums are often used as part of machineries’ controlling systems. Vacuum actuators, for instance are typically employed to drive secondary devices, such as those found in automobiles. These vacuum actuators typically use vacuum pressure to create energy that is then converted to linear or rotary motion. Vehicle accessories that are driven by actuators include headlights, ventilation systems, windshield wipers, transmission shift control systems, and many others.
There are, of course, challenges that come with designing devices such as vacuum actuators. There is a possibility that the positioning stage will outgas and corrupt the vacuum level. The opposite may also happen wherein the stage is damaged by the operation taking place inside the vacuum. Overheating is among the common causes of stage damage. This is because a vacuum chamber lacks air and can no longer be cooled by convection.
To lessen the possibility of damaging the equipment, a careful management of heat sources is needed. One major heat source in the vacuum positioning system is the motor. To reduce and monitor the heat produced by this component, many models now use strategies such as limiting the acceleration or duty cycle and lowering stepping motor drive currents.
Outgassing refers to the release of gasses trapped in certain materials. This is important as the presence of air bubbles can compromise the structural integrity of materials used in industries like construction and aerospace engineering. Gas pockets can also affect air quality in closed environments where the air is stagnant. Outgassing is carried out by baking the material in question under vacuum. This process raises the vapor pressure and boils off the outgassing substance. The process is used to de-air rubbers used for molds, and to create and maintain ultra-high vacuum environments.
A vacuum pump is typically employed in deep wells. It works by expanding the volume of a container and reducing the pressure. This leads to the creation of an artificial vacuum that is then filled by the air pushed in by the atmospheric pressure. This process of exhaustion and expansion is repeatedly done until the water fills the pump’s cavity and reaches ground level.