| 摘要 |
PURPOSE:To obtain a constant zero judging flow rate regardless of the size number of a meter, by changing the zero judging time in correspondence with the size number of the gas meter. CONSTITUTION:A flow rate sensor 2 transmits flow rate pulses corresponding to the measurement of a gas meter. A size-number selecting switch 3 generates a size number signal corresponding to the size number of the gas meter. An operating device 8 computes the flow rate from the flow rate pulses of the sensor 2 and the size number signal of the switch 3, and has a zero judging part 9, which judges the zero flow rate based on the time interval of the flow rate pulses. The judging point 9 is constituted by the following parts: a time setting device 10, which receives the size number signal and outputs a zero judging signal; a timer 5, which measures the time interval of the flow rate pulses; and a comparator 11, which compares the time interval of the flow rate pulses with the zero judging time and outputs a zero flow rate signal when the interval is longer. Therefore, the zero judging flow rate can be made constant regardless of the size number of the meter used. |
