| 摘要 |
PURPOSE:To detect precisely a temperature difference at each part in a tank and to prevent a tank rollover by leading out and measuring temperature differences between plural sensors fitted in the tank in the height direction and reference sensors fitted to a float. CONSTITUTION:The sensors 4A-4N are fitted at equal intervals from the bottom surface to the ceiling in the tank. The sensors 6 and 7 fitted to the float 5, on the other hand, are the reference sensors for measuring the temperature of a boundary surface which is not influenced by external temperature. Each sensor is a resistance temperature detector and varies in resistance value with temperature to generate a voltage; the sensor 6 and sensors 4A-4N form a current loop from a constant current source. A processor 8 scans on the sensors successively and synchronously with the reference sensor 6 to amplify and read their temperature difference voltages. Therefore, the measurement has high resolution and high precision and the tank rollover is prevented automatically to control the tank in safety. |
