To provide an ultrasonic flowmeter capable of determining whether a zero point shift (zero point abnormality) has occurred.
The ultrasonic flowmeter 1 transmits and receives ultrasonic waves between at least a pair of ultrasonic transmitter-receivers 3, 4 disposed on the upstream side and the downstream side of a flow path, and determines the flow rate based on the propagation time of an ultrasonic wave from the transmitter-receiver 3 on the upstream side to the transmitter-receiver 4 on the downstream side, and the propagation time of an ultrasonic wave from the transmitter-receiver 4 on the downstream side to the transmitter-receiver 3 on the upstream side. The ultrasonic flowmeter 1 compares the sizes of a waveform of a received signal of an ultrasonic wave transmitted and received in a forward direction and a waveform of a received signal of an ultrasonic wave transmitted and received in a forward direction, determines that abnormality is present when the difference is not less than a predetermined level and determines that abnormality is absent when the difference is less than the predetermined level.
COPYRIGHT: (C)2011,JPO&INPIT
Noriyuki Nabeshima
Hasebe Shinya
Yoshitomi Sameda
Hiroto Uyama
Takashi Michishita
Tokyo Gas Co., Ltd.
OSAKA GAS CO.,LTD.
Toho Gas Co., Ltd.
Toko Toshiba Meter Systems Co., Ltd.
| JP54143258A | ||||
| JP2008185441A |
Hiroyasu Sugiyama