Page 315 - Introduction to Marine Engineering
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Instrumentation and control 289
Orifice
plate
Flow
Pressure
tapping
Head of liquid
I- "related to
Manometer -*> fluid flow velocity
Figure 15.13 Orifice plate
outlet side (Figure 15.13). Pressure tappings before and after the orifice
plate will give a difference in head on a manometer which can be related
to liquid flow velocity.
Other variables
Moving coil meter
Electrical measurements of current or voltage are usually made by a
moving coil meter. The meter construction is the same for each but its
arrangement in the circuit is different.
A moving coil meter consists of a coil wound on a soft iron cylinder
which is pivoted and free to rotate (Figure 15.14). Two hair springs are
used, one above and one below, to provide a restraining force and also to
Scale
Soft iron
Pivot
cylinder
Figure 15.14 Moving coil meter
