Effects of gas density on the frequency response of gas-filled pressure transducers.
The effects of gas density on the frequency responses of four pressure transducers were determined at gas densities from 1.2 to 25.0 g/l. Transducers tested included three sensitive differential types used with pneumotachographs to measure respiratory flow (Validyne DP-45 and DP-103; Medistor P-11) and a transducer commonly used to measure esophageal pressure (Statham P23Dd). Three different responses were obtained. The Validyne DP-103 was overdamped and its response was essentially independent of gas density. The frequency response of this transducer is adequate for use with quiet breathing only. The Validyne DP-45 and Medistor P-11 responses were underdamped. The resonant peaks of these transducers decreased markedly in frequency as the gas density increased. The Statham P23Dd was also underdamped; however, its resonant frequency increased as gas density increased. An esophageal balloon did not alter the frequency response characteristics of this tubing-transducer system. Both increases in length and decreases in diameter of connecting tubing reduced the frequency of resonant peaks of underdamped pressure transducers.
D001274:Atmospheric Pressure; D006371:Helium; D006801:Humans; D008176:Lung Volume Measurements / Q000295:instrumentation; D009584:Nitrogen; D010100:Oxygen; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests / Q000295:instrumentation*; D014159:Transducers; D014160:Transducers, Pressure
D006371:Helium; D009584:Nitrogen; D010100:Oxygen