Abstract: Method and apparatus for monitoring the flow of coal from a bunker through a conduit to a coal feeder. A radiation sensitive detector detects the amount of coal present at a zone of the conduit and generates a stream of pulses which is sampled at discrete sample intervals of time to determine whether the conduit zone is empty, partially filled or filled. If the conduit zone is partially filled, a partial alarm is generated, and a determination is made as to whether the conduit zone is empty. If the conduit zone is empty, an empty alarm is generated and the feeder is stopped after a predetermined amount of coal has been deposited on the feeder. If the conduit zone is partially filled and a shut-off valve between the bunker and conduit is closed, a coal build-up alarm is generated. If the conduit zone is filled and the profile of coal at the feeder is not at full profile, a coal hang-up alarm is generated.