Intelligent Pressure Transducers
About the intelligent pressure transducers
Adding microprocessor power to pressure
transducers brings about substantial improvements in their
characteristics. Improved measurement sensitivity, extended
measurement range, compensation for hysteresis and other non-linearities,
and correction for ambient temperature and pressure changes are just
some of the facilities offered by intelligent pressure transducers.
Accuracies of ±0.1% can be achieved with piezoresistive-bridge silicon
devices, for instance. In view of their much superior characteristics,
it is perhaps surprising that intelligent pressure instruments
represent only about 1% of the total number of pressure measuring
devices sold at the present time. The significantly higher cost
compared with non-intelligent devices has been cited as the reason for
this, but this hardly seems adequate to explain such a very low level
of market penetration.
Some recent microprocessor-based pressure transducers make use of
novel techniques of displacement measurement. For example, both
diaphragm and helical Bourdon-tube devices are now available which use
an optical method of displacement measurement of the form. In this,
the motion is transmitted to a vane which progressively shades one of
two monolithic photodiodes that are exposed to infrared radiation. The
second photodiode acts as a reference, enabling the microprocessor to
compute a ratio signal which is linearized and is available as either
an analog or digital measurement of pressure. The measurement accuracy
is typically ±0.1%.
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Pressure Measurements
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