Reading analog scales

Instrumentation and Process Control

  • Question 1

    Interpret the pressure measurement displayed by this gauge mechanism, assuming a gauge accuracy of $\pm$ 1

    How low and how high could this pressure actually be, given the stated accuracy of this gauge?

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  • Question 2

    Interpret the pressure measurement displayed by this gauge mechanism, assuming a gauge accuracy of $\pm$ 2

    How low and how high could this pressure actually be, given the stated accuracy of this gauge?

    Reveal answer
  • Question 3

    Interpret the pressure measurement displayed by this gauge mechanism, assuming a gauge accuracy of $\pm$ 0.5

    How low and how high could this pressure actually be, given the stated accuracy of this gauge?

    Reveal answer
  • Question 4

    Interpret the pressure measurement displayed by this gauge mechanism, assuming a gauge accuracy of $\pm$ 2

    How low and how high could this pressure actually be, given the stated accuracy of this gauge?

    Reveal answer
  • Question 5

    Interpret the pressure measurement displayed by this gauge mechanism, assuming a gauge accuracy of $\pm$ 2

    How low and how high could this pressure actually be, given the stated accuracy of this gauge?

    Reveal answer
  • Question 6

    Interpret the pressure measurement displayed by this U-tube manometer, recalling that the pressure will be equal to the {\it difference} in heights between the two liquid columns:

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  • Question 7

    Interpret the temperature measurement displayed by this gauge mechanism, and also identify the meaning of the {\it other} pointer:

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  • Question 8

    Interpret the measurement displayed by this pneumatic controller:

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  • Question 9

    Interpret the air flow measurement displayed by this rotameter:

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  • Question 10

    Machinists use a tool called {\it calipers} to measure short distances such as the outside diameter of a shaft. One particular type of caliper has a special scale that slides along with the movable jaw called a {\it vernier} scale. The spacing between divisions on the vernier scale is slightly less than the spacing between divisions on the main scale, which means only one division on the vernier scale will ever line up with a division on the main scale at any given time:

    In order to obtain a coarse measurement of the caliper’s jow position, read the main scale using the ``0’’ mark on the vernier scale as a pointer:

    Now, use the vernier scale to read the distance between the caliper’s jaws, when the ``0’’ division on the vernier scale does {\it not} line up perfectly with one of the divisions on the main scale:

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  • Question 11

    Interpret the distance between the jaws of this {\it vernier} caliper:

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  • Question 12

    Some precision manometers are equipped with a {\it vernier} scale in order to make very precise measurements of liquid column height.

    Interpret the reading shown on this mercury manometer. Note: the ``hairline’’ on the moving vernier scale is adjusted to the meniscus height by a screw prior to taking the reading:

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