Measurement performance of high-accuracy low-pressure transducers

A systematic study of measurement performance is described for several diff erent types of transducer including capacitance diaphragm gauges (CDGs), qu artz Bourdon gauges (QBGs), quartz resonant gauges (QRGs), and two types of MEMS (MicroElectroMechanical Systems) sensors - piezoresistive silicon gau ges (PSGs) and resonant silicon gauges (RSGs). Key factors limiting their p erformance were identified as random noise, short-term instabilities in zer o-pressure readings, long-term shifts in a transducer's calibration with ti me and, in the case of heated gauges, the effect of thermal transpiration. The study determined that CDGs, QBGs, and QRGs have superior noise-limited pressure resolution (about 1 part in 10(6) of full scale), though CDGs, bec ause of their availability with lower full-scale ranges, have the best abso lute pressure resolution. Analyses of calibration data indicated that QBGs, QRGs and RSGs have the best long-term stability, with average calibration shifts of the order of 1 part in 10(4) per year, one to two orders of magni tude smaller than those observed for CDGs.