1024 Lecture 1: pressure measuring instruments
Document Summary
Four basic types of pressure measuring instruments: liquid column elements. It is made up of a column of liquid in a tube with different pressures exposed at each end. The column will rise or fall until its weight equals the pressure difference between the two ends of the tube: barometer. A barometer is a device used to measure local atmospheric pressure. Because atmospheric pressure changes with distance above or below sea level, it can also measure altitude. A mercury barometer is shown in the figure below, which is made up of a 1-meter- long glass tube closed at one end and filled with mercury and held inverted in a bowl of mercury. A small amount of mercury will drop into the bowl, creating a vacuum at the upper end of the tube. In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured.
