In 1808, a baby boy named Eugene Bourdon was born in Paris, France and grew up to make it on the prestigious list of notable inventors. Beginning his career as a watchmaker, he eventually moved on up the ladder as an engineer, ultimately hitting the nail on the head with his invention of what is appropriately referred to as the Bourdon gauge. You might be wondering, as was I, why this particular kind of gauge has everyone excited; the answer to this lies in its unique mechanism based on the understanding that a flattened tube will fill out and straighten when pressurized. Such a transformation is small, but, in this case, magnified by arranging the tube into a C shape, thus allowing the tube to properly alter itself as it is being pressured. This model, as it was quickly understood, exhibits a superior and precise accuracy.
This type of gauge remains one of the most commonly used tools for measuring the pressure of liquids and gases, more specifically ambient atmospheric pressures— in other words, vacuum pressures. “Vacuum” is defined as space that is empty of matter, but in this case it merely and more realistically refers to a gaseous pressure that is significantly less than the atmospheric pressure. An example of such a space would be a typical vacuum cleaner, which, like its name implies, creates a high enough suction in order to reduce air pressure by roughly 20%. More extreme examples of low-pressurized enclosed areas are basically only found in contexts of chemistry, physics and engineering.
So to summarize, a vacuum pressure gauge is used to measure the extent in which a particular area has been expelled of matter; outside of a scientist’s theoretical ponderings, this cannot happen entirely, ergo vacuum pressure gauges are used to measure low pressure, not negative pressure— the lower the gas pressure, the higher-quality the vacuum. Such gauges are generally made from stainless steel or aluminum and are offered with either analog or digital meters.