Closed-Tube Manometer

Definition

A closed-tube manometer is a device used to measure pressure in a system by comparing the pressure of the system to a known reference pressure. It consists of a U-shaped tube filled with a liquid, typically mercury or water, and is used to determine the absolute or gauge pressure of a fluid or gas.

5 Must Know Facts For Your Next Test

1. The closed-tube manometer is used to measure both gauge pressure and absolute pressure by comparing the pressure in the system to the reference pressure of the liquid column.
2. The difference in the height of the liquid column in the two arms of the U-shaped tube is directly proportional to the pressure difference between the system and the reference pressure.
3. Closed-tube manometers can be used to measure both positive and negative pressures, as the liquid column can rise or fall depending on the pressure difference.
4. The accuracy of the closed-tube manometer depends on the density of the liquid used, the precision of the measurements, and the stability of the reference pressure.
5. Closed-tube manometers are commonly used in various applications, such as in the measurement of fluid pressures in hydraulic and pneumatic systems, as well as in the monitoring of atmospheric pressure changes.

Review Questions

• Explain how a closed-tube manometer is used to measure gauge pressure.
  • A closed-tube manometer is used to measure gauge pressure by comparing the pressure in the system to the surrounding atmospheric pressure. The difference in the height of the liquid column in the two arms of the U-shaped tube is directly proportional to the pressure difference between the system and the atmospheric pressure. By measuring this height difference, the gauge pressure of the system can be determined.
• Describe the relationship between gauge pressure and absolute pressure as measured by a closed-tube manometer.
  • A closed-tube manometer can be used to measure both gauge pressure and absolute pressure. Gauge pressure is the pressure above or below the surrounding atmospheric pressure, while absolute pressure is the total pressure acting on the system, including the atmospheric pressure. The closed-tube manometer measures the difference in pressure between the system and the reference pressure (typically the atmospheric pressure). By adding the atmospheric pressure to the measured gauge pressure, the absolute pressure of the system can be determined.
• Evaluate the factors that influence the accuracy of a closed-tube manometer in pressure measurement.
  • The accuracy of a closed-tube manometer in pressure measurement depends on several factors. The density of the liquid used in the U-shaped tube is crucial, as it determines the sensitivity of the device. The precision of the height measurements in the two arms of the tube is also important, as small variations can lead to significant errors in the pressure reading. Additionally, the stability and consistency of the reference pressure, typically the atmospheric pressure, can impact the accuracy of the measurements. Other factors, such as the cleanliness of the tube, the angle of observation, and the temperature of the system, can also affect the overall accuracy of the closed-tube manometer.

Related terms

Gauge Pressure: Gauge pressure is the pressure measured relative to the surrounding atmospheric pressure. It represents the pressure above or below the ambient pressure.

Absolute Pressure: Absolute pressure is the total pressure acting on a surface, including the atmospheric pressure. It is the sum of the gauge pressure and the atmospheric pressure.

Pressure Measurement: Pressure measurement is the process of quantifying the force exerted by a fluid, gas, or solid on a surface, typically using specialized instruments like manometers, barometers, or pressure transducers.