Automatic level control for film processing bath - has conductivity monitor and automatic replenisher, and compensates for evaporation losses from process tank

摘要

The electrodes (1) provide a passive monitor in the process tank with their output processed by an amplifier and compared with a programmed value in a control unit (3). Any deviation from the control value operates an infinitely adjustable supply pump (4) to pump more water into the process tank from a header tank (5). The system compensates for evaporation losses from the heated process tank. A failsafe control operates a time delay after the process tank is switched on to allow the recirculating pump (8) to mix the process fluids evenly. The system provides constant quality over long periods.