• level detectors. There are two different types of level detection: point level detection and continuous level detection. Point level detectors are typically attached to the side wall or roof of a bin, and measure solids by direct contact using capacitance sensors, pressure diaphragms, or other means of proximity sensing. Common point level detectors include rotary paddles, tilt switches, and vibrating rods. Continuous level detectors usually consist of a roof-mounted device that emits radar or ultrasonic signals. The signals project down to the surface of the bulk material, and then rebound to a receiver for processing. Ultrasonic, guided-wave radar, or plumb-bob (i.e., yo-yo) detectors are commonly used to provide continuous detection of the top surface of the bulk material.