Three units of pressure

Thread Content

①By the direct definition of pressure, it is the force per unit area; its unit should be N/m2, also known as Pascal (Pa). 10^5 times of this value is called a bar, meaning 1 bar = 10^5 Pa. ②It is indirectly expressed in terms of the height of the fluid column, such as in mH2O or mmHg. The relationship between the height of the liquid column h and the pressure is p = pgh. Note that when pressure is expressed in terms of the liquid column height h, it is necessary to specify simultaneously what kind of fluid or its density. ③Atmospheric pressure is used as the unit of measurement. 1 atm (standard atmospheric pressure) = 1.013×10^5 Pa, which is equivalent to 760 mmHg or 10.33 mH2O. Previously, in engineering, 1 kgf/cm2 was also commonly used as a unit of pressure, known as engineering atmosphere (at). 1 at = 1 kgf/cm2 = 9.81×104 N/m2, which is equivalent to 735.6 mmHg or 10 mH2O.