| 摘要 |
PURPOSE:To improve the simplicity and reliability of maintenance by measuring the density and level of liquid by using a differential pressure gauge. CONSTITUTION:A liquid level signal H is led out of the differential pressure gauge 13 by introducing atmosphereic pressure in the low pressure side of the differential pressure gauge 13 by powering on a three-way solenoid valve 15 and supplied to a holding circuit through a selection switch 20. The holding circuit 21 holds the liquid level signal H before the three-way solenoid valve 15 is powered off. Once the three-way solenoid valve 15 is powered off, the low pressure side of the differential pressure side receives the hydraulic pressure of a high position corresponding to the passing of piping 16, so pressure H0rho is applied to the high pressure side of the differential pressure gauge 13 and pressure (H0-h)rho is applied to the low pressure side respectively, outputting a differential pressure signal hrho. In this case, (h) is constant, so this signal is used as a concentration signal as it is, and supplied to a holding circuit 22 through the selection switch 20 to hold the density signal rho before the power-on operation starts. Consequently, an actual liquid level signal H0 is outputted from an arithmetic circuit 23. |
