| 摘要 |
PROBLEM TO BE SOLVED: To improve detection accuracy of a gas flow rate, using pulsed ultrasonic waves. SOLUTION: A pair of ultrasonic flowmeters is installed on a pipe of each gas apparatus, and set in a detection mode (S11). The pulsed ultrasonic wave of about 50 kHz is irradiated from the ultrasonic flowmeters, and the arrival time of the ultrasonic wave or its frequency is measured, to thereby detect a gas flow rate (S12). Thereafter, when for example, a sudden change in the gas flow rate or the like occurs (S13), collected output of the ultrasonic wave is compared with that in a steady state. When an abnormal change of the gas flow rate is detected, it can be determined that an abnormal gas flow rate is generated, and that an abnormal state is occurring (S14). Then, abnormality information of that time, a gas apparatus or the like is transmitted to an information apparatus (S15). When the abnormality information is received by the information apparatus (S16), the abnormality information is displayed on a screen as an information screen (S17). Furthermore, the abnormality information is notified in a call placed to a cellular phone to inform of these abnormal state (S18). COPYRIGHT: (C)2008,JPO&INPIT
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