15.4 : Measurement of Fluid Pressure

Fluid pressure is commonly measured using devices called manometers, which rely on liquid columns to indicate pressure differences. The height of a liquid column in a manometer reflects the pressure exerted by the fluid, providing a simple yet effective means of measurement. Different types of manometers serve specific purposes based on their configurations and the type of fluids involved.

A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same fluid whose pressure is measured. When connected to a fluid container, the height of the fluid in the tube correlates directly with the pressure inside the container. For more complex applications, the U-tube manometer uses a U-shaped tube filled with a gauge fluid that does not mix with the fluid being measured. This setup allows for differential pressure measurements between two points.

Another variant is the inclined-tube manometer, which has one leg tilted. This inclined leg enhances sensitivity by stretching the measurement scale along the incline, allowing for precise readings of small pressure differences.

Beyond manometers, there are other tools for measuring fluid and atmospheric pressure. The Bourdon gauge, for instance, is widely used to measure gas or liquid pressures in various industrial applications, while the aneroid barometer measures atmospheric pressure and is commonly used in weather forecasting and altitude measurements.