METHOD FOR DETECTING GAS MICRO-FLOW, METHOD FOR DETECTING GAS LEAK, GAS LEAK INSPECTION DEVICE, AND ULTRASONIC FLOWMETER

摘要

PROBLEM TO BE SOLVED: To provide a method for detecting a gas micro-flow capable of detecting the gas micro-flow while suppressing enlargement of the structure and an increase in product price; and to provide a method for detecting a gas leak, a gas leak inspection device and an ultrasonic flowmeter.;SOLUTION: In an ultrasonic flowmeter 10 according to the present invention, a flow cell 20 is connected to a midway part of a gas pipe 90, first gas is accumulated in a measuring duct 22, or an internal space thereof, second gas whose propagation velocity of ultrasonic waves is different from that of the first gas is injected and accumulated from the outside of the measuring duct 22 and in the state, the propagation velocity of the ultrasonic waves is measured over a prescribed monitoring period. Then, a transition in the propagation velocity (actual measurement transition data) with a time lapse from the time when the second gas is accumulated, is compared with a transition (reference transition data) in the propagation velocity when the second gas is naturally diffused with the flow rate of the first gas set to 0, to determine the presence/absence of the gas leak.;COPYRIGHT: (C)2012,JPO&INPIT