| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique for determining accurately leakage of a fluid and a using implement, in view point of a variation width in a flow rate value. SOLUTION: This flow measuring instrument measures the flow rate value of gas flowing in a flow channel 6 of a gas meter 16, by an ultrasonic flowmeter 7, and stores the measured flow rate value by a measured flow rate information storage part 8. A flow rate variation width calculating part 9 calculates the flow rate variation width corresponding to a variation amount of the measured flow rate value. A state determination part 11 determines whether the flow rate variation width is within the first prescribed variation width threshold value or not, and determines the leakage of the gas and the using implement, based on a determination reference of determining whether an integrated frequency exceeds a prescribed integrated frequency threshold value or not, using the integrated frequency added when the flow rate variation width is smaller than the first variation width threshold value, and subtracted when the flow rate variation width is the first variation width threshold value or more, in a prescribed period. The integrated frequency is reset and a determination operation is stopped, when the flow rate variation width comes to the second variation width threshold value or more. COPYRIGHT: (C)2009,JPO&INPIT
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