| 摘要 |
PURPOSE:To measure a liquid level independent of temperature change of liquid by calculating ultrasonic wave propagation speed on the basis of a signal from an ultrasonic wave measurer connected to an ultrasonic wave transciever mounted on the bottom wall face of a liquid housing part, finding temperature of the bottom wall, and calculating a liquid level from the temperature and a measured signal. CONSTITUTION:An ultrasonic wave transceiver 3 is mounted on the bottom wall face of piping 1, and an ultrasonic wave measurer 5 is connected thereto. An ultrasonic wave is propagated and transmitted in the bottom wall of the piping 1 and in liquid on the basis of a signal from the transceiver 3, the measurer 5 measured a time t1 up to receiving of an echo wave reflected on a liquid surface 2, and time t2 up to receiving of the cho wave in the bottom wall from transmission of the ultrasonic wave. A liquid level is found from a time interval of the echo wave and an ultrasonic wave propagation speed in the liquid found by the measurer 5, at that time, the propagation speed is calculated by a temperature operation device 8 on the basis of the time t2 and bottom wall thickness, and the bottom wall temperature, namely, temperature of the liquid is found. In response to the temperature signal a correction of the propagation speed in accordance with the time t1 is performed by an operation processor 6 and the liquid level is obtained. |
