| 摘要 |
An actual-value sensor (20) is situated in a container which contains the liquid and into which an additive which increases or reduces the physical variable is introduced as a function of the variable. The actual-value sensor (20) and a set-point generator (21) are connected to a comparator circuit (34) having two outputs which are each connected to two timing circuits (36, 39; 41, 44). Depending on the actual value, the timing circuits and actuators connected to their outputs open a solenoid valve in each case in the feed line of one additive or switch on a metering unit for the pump, or open a solenoid valve in the feed line of the other additive or switch on a metering unit for the other pump. Simultaneously, an alarm function can be triggered if specified limit values are exceeded. <IMAGE> |
