Complex sentence: The coil of the valve solenoid must be connected in series with all of there elements and for this fuel, air and steam pressure can be converted to an electrical signal by means of a bellows, bourdon tube, or diaphragm operated mercury switch.
Split into simpler sentences: The coil of the valve solenoid must be connected in series with all of the elements. For this to operate, fuel, air and steam pressure can be converted to electrical signals by means of bellows, bourdon tube, or diaphragm operated mercury switch.