| 摘要 |
PURPOSE:To permit whether pumping impossibility is due to air-lock phenomenon or not to be correctly judged by installing a pressure detecting means onto a pump and detecting the variation of the pump discharge pressure with lapse of time. CONSTITUTION:A pressure detector 10 detects the discharge pressure of a pump 2 and transmits a signal to a control circuit 12 which is provided with the automatic inspection function for pump and the operation control function for motor, through A/D conversion by means of a signal converter 11, and the output of the control circuit 12 is sent into a motor 3. When the pump 2 itself is in the trouble such as water leak and increase of resistance in water suction pipe, a constant pressure lower than the pressure shown by a normal discharge pressure line 13 is generated. When the pump 2 is put into shut-off operation and started at a time T1, the discharge pressure is varied as shown by a curve 15, if air-lock phenomenon is generated in the pump. Therefore, whether the pumping impossibility is due to air-lock or not can be correctly judged. |
