LEDs for line (pressure alarms min/max, OK), triple color bargraph for left and right sources, showing as percentage bars the filling of cylinder, alarm and pre-alarm (green if OK, yellow if in pre-alarm, red if in alarm), LEDs to indicate the working source, acoustical alarm.
The unit can perform the automatic switching over of source and also allows the operator to switch by himself.
Needs transducers and electrovalves (if the switching has to be operated by the unit).