Bar
The bar is a pressure unit in the metric system, equivalent to 100,000 pascals. It was created in the early 1900s to serve the needs of engineers and industry professionals, especially for measuring pressures in the atmosphere and fluids. While it is not officially a part of the SI system, the bar remains popular in fields such as meteorology, diving, and mechanical engineering because of its convenient scale. For example, normal atmospheric pressure at sea level is close to 1.013 bar. The bar provides an easy-to-use alternative to SI units for everyday applications while still maintaining compatibility with metric measurements.
Torr (mmHg)
The torr, symbolized as Torr, is a pressure unit equal to 1/760 of a standard atmosphere, approximately 133.322 pascals. Named for Evangelista Torricelli, inventor of the mercury barometer, the torr was historically central in vacuum measurement and laboratory work. This unit offers a practical scale for low pressures, particularly in physics and chemistry. While mostly replaced by SI units, such as the pascal, the torr remains essential in high-precision scientific instruments and measurements worldwide.