involving a closed chamber above the liquid level, the chamber being exhausted or housing low-pressure gas; Liquid barometers

Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements > using liquid as the pressure-sensitive medium, e.g. liquid-column gauges > involving a closed chamber above the liquid level, the chamber being exhausted or housing low-pressure gas; Liquid barometers

Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements ( transmitting or indicating the displacement of mechanical pressure-sensitive elements by electric or magnetic means G01L9/00; measuring differences of two or more pressure values G01L13/00; measuring two or more pressure values simultaneously G01L15/00) > using liquid as the pressure-sensitive medium, e.g. liquid-column gauges > involving a closed chamber above the liquid level, the chamber being exhausted or housing low-pressure gas; Liquid barometers