mm of mercury
The millimeter of mercury (mmHg) is pressure unit traditionally used in meteorology. It is the pressure from a 1 mm column of mercury at 0°C under normal gravity.
pound force per square inch
Pound force per square inch (psi) is a unit from the Imperial system defined as the pressure resulting from a force of one pound-force applied to an area of one square inch. It is used in various applications such as tire pressure and hydraulic systems.