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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