[Study of the pneumotachograph with the Pito tube]

The pneumotachograph with a velocity head flowmeter and a linearization system has been studied. Theoretical and experimental results have revealed a possibility to design a multilevel pneumotachograph with the Pito tube providing gas output measurements at a wide respiration range while the slight flow resistance and the small dead space being maintained. It also allows for undisturbed data recording. Characteristic properties of a piecewise-linear correction may be used to gain the required accuracy in the presence of a variability of the following parameters: ambient temperature, gas temperature, humidity and density, electromanometer's conversion ratio, baseline drift, spreads in dimensions of breathing tubes, etc. Delta-unit designed for in-line recording the pneumotachograph errors increases markedly an experimental capacity and may be used for calibration testing at plants.