Manometer

Description

Here were are looking at three manometers. On the left hand side, the round flasked is called a bulb which is filled with gas. The gas pressure in a bulb can be measured using a manometer. The difference in the mercury liquid heights tells us the difference in pressure between the bulb and the atmospheric pressure. If the liquid is mercury, the pressure units are millimeter mercury or centimeter mercury. If the liquid is something else such as water or oil, the density has to be used to calculate the pressure in millimeter mercury.