The flow system of Figure 1.3(c) has an orifice plate sensing element; this gives
a differential pressure output. The differential pressure transmitter converts this into
a current signal and therefore combines both sensing and signal conditioning stages.
The ADC converts the current into digital form and the computer calculates the flow
rate, which is obtained as a permanent record on a chart recorder.
The weight system of Figure 1.3(d) has two sensing elements: the primary element
is a cantilever which converts weight into strain; the strain gauge converts this
into a change in electrical resistance and acts as a secondary sensor. There are two
signal conditioning elements: the deflection bridge converts the resistance change into millivolts and the amplifier converts millivolts into volts. The computer corrects for
non-linearity in the cantilever and the weight is presented on a digital display.
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