| 摘要 |
PROBLEM TO BE SOLVED: To allow inexpensive constitution using a piezoelectric ceramic element (PZT) even in high-temperature fluid, and to control a temperature gradient of a flow measuring part at a constant value to allow highly precise measurement. SOLUTION: An ultrasonic echo-sounder transceiver is brought over outwards from a measuring tube by a prescribed distance to be attached to both end parts of an attching tube, so as to form a cooling space. The temperature gradient inside the cooling space is controlled at the constant value by a temperature control means comprising a temperature detecting means, a temperature controller and the like. The temperature controller supplys temperature-controlled air controlled at a set temperature into the cooling space. A temperature exceeding the Curie temperature of an ultrasonic oscillator is precluded even in the high-temperature fluid, and a measuring error based on the dispersion of the temperatures in the cooling space which is the flow measuring part is prevented to allow the highly precise measurement.
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