Vacuum trivia

What is vacuum?

According to the dictionary, vacuum is "a space entirely devoid gas or matter", or "a state of nothingness". In scientific terms, a space literally void of matter is known as a "perfect vacuum". However, this state is currently unexplored, and a "perfect vacuum" is more of a theoretical concept. On this point, in the minds of our predecessors, vacuum was simply a pressure lower than atmospheric pressure (i.e. not 1 atm)". Currently, under the JIS definition, vacuum is defined to be "a specific state of a space filled with a gas that is at a pressure below atmospheric pressure". Accordingly, when we breath, the pressure inside our our lungs when they are expanded is below atmospheric pressure, and therefore there is a vacuum inside our lungs. Come to think of it, a kiss also makes use of vacuum. (^_^;)

What is vacuum?

What kind of state is vacuum?

Vacuum is not a thing; it is a state. A state of vacuum represents pressure. The unit of pressure is the Pascal (Pa). In order to make the condition of a vacuum easy to understand, let's consider the relationships between elevation/altitude and a state of vacuum.

Elevation/Altitude Degree of Vacuum Equiv. Vapor
0m 0kPa Atmosphere at Sea Level
333m 4kPa Atmospheric pressure at ORION Machinery (Suzaka City, Nagano Pref.)
3776m 38kPa Atmospheric pressure at the peak of Mt. Fuji
6000m 54kPa Continuous degree of vacuum of a KRF04A Dry Pump
7000m 60kPa Continuous degree of vacuum of a KRF70 Dry Pump
10000m 75kPa Continuous degree of vacuum of a KRF15 Dry
Pump Airspace around a commercial jetliner
20km 94kPa Ultimate pressure of a KHA Series Dry Pump
Ultimate pressure of a KCP Oil-Free Pump
25km 100kPa Continuous degree of vacuum of a KHH Dry Pump
Ultimate vacuum of a KCM Oil-Free Pump
Airspace around a man-made satellite
1000km 1.33×10-11kPa(abs) Outer space

※ Note that the written degrees of vacuum show both the atmospheric pressure standard and the absolute pressure standard, using the same units.

About the Displayed Degree of Vacuum
About the Displayed Degree of Vacuum

For example, the flying altitude of a jetliner is approx. 10,000 m. The vacuum conditions in this airspace is 75 kPa, so if someone uses a KRF15 dry pump, he is producing the same amount of vacuum that occurs in the airspace of a jetliner.

What is vacuum?