9 AUTOMATED ELECTRONIC MONITORING INSTRUMENTS USED IN POWER PLANTS AND FOUNDRIES-NAMELY, BOILER CONTROLS AND REGULATORS; BURNER IGNITION CONTROLS AND REGULATORS; SMOKE DENSITY INDICATOR LEVELS; PHOTOELECTRIC SMOKE OPACITY METERS; TEMPERATURE REGULATORS AND METERS; AND SAFEGUARD INSTRUMENTS-NAMELY, TRIPS, INTERLOCKS, AND ALARMS