| 摘要 |
PURPOSE:To accurately measure a wide range of liquid levels by placing an ultrasonic transmitter/receiver which transmits ultrasonic pulses into the liquid in a liquid tank or a liquid level indicator tube and receives reflected waves from a liquid surface inside or at a lower part outside the liquid tank or the liquid level indicator tube. CONSTITUTION:An ultrasonic transmitter/receiver 15 is placed oppositely to a liquid surface 3a on a lower face of a lower fixing metal 4 of a liquid level indicator tube 2, while the transmitter/receiver 15 is attached to the lower fixing metal 4 by a cover-like fixing jig 16. The transmitter/receiver 15 generates for example ultrasonic pulses of 2.25 MHz. The ultrasonic waves generated from the transmitter/receiver 15 pass through the lower fixing metal 4 and the liquid 3 and are reflected on the liquid surface 3a to be received by the transmitter/receiver 15 via the same route. By thus measuring a liquid level with the ultrasonic waves propagated in the liquid, linearity in a relation between measurement time and a measured distance is better than a case where the ultrasonic waves are propagated in the air, thereby improving measurement accuracy. |
