Input I1 is the thermostat that monitors the temperature of the container. In the case of critical temperature is reached the pump switches for adding coolant. I2 represents the input switch Auto / Manual. In manual control the pump operation guarding. Time-shifting circuit monitors the delayed start, both in operations (B03) and turn off the circuit (B06). The actual switch represents samotržné relay (B02), the output state is controlled by the input signal Reset.
Circuit schema in FBD: