Patent ID: 8746037
Filing Date: 2014-06-10
Classification: G01N

Abstract:
1. An ultrasonic method for measuring the concentration of a specific component gas in a sample gas based on a propagation time till an ultrasonic wave transmitted from two ultrasonic transducers transmitting/receiving the ultrasonic wave, arranged opposite to each other in piping through which the sample gas flows, is received by the ultrasonic transducer arranged on the opposite side, the method comprising steps of: measuring a propagation time till the ultrasonic wave transmitted from each of the two ultrasonic transducers is received by the other ultrasonic transducer; measuring a sample gas temperature measuring a sample gas pressure; and correcting the propagation time till the ultrasonic transducer receives the ultrasonic wave based on a propagation speed correction coefficient according to the temperature and pressure of the sample gas, wherein the step for correcting the propagation time till the ultrasonic transducer receives the ultrasonic wave is a step for correcting a propagation speed (C) of the ultrasonic wave by the following expression: the propagation speed correction coefficient B(T) is acquired as an approximate function of the measured temperature T calculated from an ultrasonic propagation speed C at a given temperature T under different pressure conditions, measured from an ultrasonic propagation time till the ultrasonic wave transmitted from the two ultrasonic transducers transmitting/receiving the ultrasonic wave and wherein B(T)=αT