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.
Pounds per Square Inch (psi)
The pound per square inch, symbolized as psi, is an imperial pressure unit defined as one pound-force per square inch. It originated in the United States and the UK for industrial, automotive, and engineering uses. Psi remains the standard for tire pressure, hydraulic systems, and pipelines in countries that use the imperial system. Its frequent application in daily contexts and need for conversion with metric units underscore the importance of precise metric-imperial conversions in trade, safety, and engineering.