key term - Manometer

Definition

A manometer is a device used to measure pressure, particularly the pressure of fluids or gases. It is a crucial instrument in the study of fluid mechanics and is closely related to the concepts of pressure, variation of pressure with depth in a fluid, and the measurement of both gauge and absolute pressure.

5 Must Know Facts For Your Next Test

1. Manometers are commonly used to measure the pressure of fluids, such as water, oil, or gases, in various industrial and scientific applications.
2. The basic principle of a manometer is to measure the difference in height between two columns of fluid, which is directly proportional to the pressure difference.
3. Manometers can be classified as either open-ended or closed-ended, depending on the configuration of the fluid columns.
4. The type of fluid used in a manometer, such as water or mercury, can affect the sensitivity and range of pressure measurements.
5. Manometers are essential for measuring the pressure drop across components in fluid systems, such as pipes, valves, and filters, which is important for understanding system performance.

Review Questions

• Explain how a manometer is used to measure the pressure of a fluid.
  • A manometer measures the pressure of a fluid by comparing the height difference between two columns of fluid, one connected to the fluid whose pressure is being measured and the other open to the atmosphere. The difference in the heights of the two fluid columns is directly proportional to the pressure difference between the fluid and the atmosphere, according to the principle of hydrostatic pressure. By measuring this height difference, the manometer can provide a quantitative measurement of the fluid's pressure.
• Describe the role of a manometer in understanding the variation of pressure with depth in a fluid.
  • Manometers are crucial for studying the variation of pressure with depth in a fluid, as they can directly measure the pressure at different depths within the fluid. By connecting one end of a manometer to a specific depth in a fluid, the height difference between the two fluid columns will indicate the pressure at that depth. This allows for the experimental verification of the relationship between pressure and depth, as described by the hydrostatic pressure equation: $P = \rho gh$, where $P$ is the pressure, $\rho$ is the fluid density, $g$ is the acceleration due to gravity, and $h$ is the depth. Manometers enable the direct measurement of this pressure-depth relationship in various fluid systems.
• Analyze the differences between gauge pressure and absolute pressure, and explain how a manometer can be used to measure both.
  • Gauge pressure is the pressure measured relative to the surrounding atmospheric pressure, while absolute pressure is the total pressure acting on a surface, including both the gauge pressure and the atmospheric pressure. A manometer can be used to measure both gauge pressure and absolute pressure. When one end of the manometer is open to the atmosphere, the height difference between the two fluid columns indicates the gauge pressure. However, if the manometer is connected to a sealed system, the height difference will represent the absolute pressure, as the atmospheric pressure is also acting on the fluid columns. By understanding the relationship between gauge pressure, absolute pressure, and the measurements provided by a manometer, one can accurately determine the pressure conditions in various fluid systems.

Related terms

Pressure:

The force exerted per unit area on a surface, measured in units such as pascals (Pa) or pounds per square inch (psi).

Gauge Pressure:

The pressure measured relative to the surrounding atmospheric pressure, often displayed on pressure gauges.

Absolute Pressure:

The total pressure acting on a surface, including both the gauge pressure and the atmospheric pressure.