Temperature monitoring and control by sensing soaking zone temperature and regulating the air and fuel control valves by means of a PID controller, which can be either pneumatically or electrically actuated. The air : fuel ratio is built into the controller software.  One of the noteworthy features of the temperature loop is the special facility provided for manual intervention – on occurrence of a mill breakdown, the furnace temperature can be turned down to pre-determined levels simply at the click of a button.