Experimental validation of an improved mathematical model for pneumatic pressure measurement systems with connecting tubes

Abstract

In many industrial applications pressure sensors often have to be placed at a certain distance from the measured object and a tube that connects the measured object and the pressure sensor is then a component part of the pressure measurement system. The dynamic response of such a measurement system depends on the properties of the transmission fluid, and on the characteristics of the connecting tube and the sensor volume. This paper experimentally validates an improved mathematical model that supplements the Bergh and Tijdeman model with the frequency-dependent thermodynamic effects on the gas density changes in the sensor volume. The quality of the mathematical model was evaluated in terms of the limit frequencies of the pneumatic pressure measurement system with connecting tubes of different dimensions, which define the useful frequency ranges from the viewpoint of the magnitudes of the amplitude dynamic errors. The results show that the improved mathematical model enables a better estimation of the limit frequency, with relative deviations between the theoretically and experimentally obtained limit frequencies not exceeding 14%. The uncertainty analysis of the deviations, which considers the contributions of the uncertainties of the modelling input data and the uncertainties related to the measurements, confirms the validity of the considered frequency-dependent thermodynamic effects in the sensor volume.