A micromanometer is used for the accurate measurement of extremely small pressure differences. The micromanometer is another variation of liquid column manometers based on the principle of an inclined tube manometer. The meniscus of the inclined tube is at a reference level as shown in Fig.1, viewing through a magnifier provided with a cross hairline. This is done for the condition, P1 = P2. The adjustment is done by moving the well up and down a micrometer. For the condition when P1 ≠ P2, the shift in the meniscus position is restored to zero by raising or lowering the well as before and the difference between these two readings gives the pressure difference in terms of height.

Fig.1: Micromanometer

Micromanometer is a static fluid pressure difference measuring device. Its dynamics can rarely be ignored. Considering manometric fluid as a free body, the forces acting on it are

  1. The weight is distributed over the entire fluid.
  2. The drag force is due to its motion and the corresponding tube wall shearing stress.
  3. The force is due to differential pressure.
  4. Surface tension force at the two ends.
Make sure you also check our other amazing Article on : Differential U-tube Manometer
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