Well-Type Manometer (Cistern Manometer)
About the well-type manometer or cistern
manometer
The well-type manometer is effectively a U-tube manometer in which one-half of the tube
is made very large and takes the form of a well. The change in the
level of the well as the measured pressure varies is negligible.
Therefore, the liquid level in only one tube has to be measured, which
makes the instrument much easier to use than the U-tube manometer. The
gauge pressure is given by:
P1 = hp
It might appear that the instrument would give a better measurement
accuracy than the U-tube manometer because the need to subtract two
liquid-level measurements in order to arrive at the pressure value is
avoided. However, this benefit is swamped by errors which arise due to
the typical variations in cross-sectional area in the glass used to
make the tube. Such variations do not affect the accuracy of the
U-tube manometer.
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Pressure Measurements
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