(under subclass 504) Subject matter which operate an alarm or indicator should dangerous conditions arise in the boiler, usually by a thermally-operated means which is exposed to the steam when the water-level falls below a certain limit.
SEE OR SEARCH THIS CLASS, SUBCLASS:
504.1, for fusible controls.
SEE OR SEARCH CLASS
340, Communications: Electrical,
500+, for electrical automatic condition responsive indicating systems.
