GRANULAR BODY GAUGE

PURPOSE:To detect whether or not granular bodies are present thereon by providing a thin plate which contacts granular bodies and can be vibrated on a part of a storage tank wall. CONSTITUTION:When an exciting signal (a) of low frequency is applied from a driving circuit 6 to an exciting element 4 and the level of granular body is A, only a small-amplitude output (b) is obtained by a reception element 5. When the level is C, the vibration of the element 4 is not attenuated and the output of the element 5 has a large amplitude as shown by (c). A comparator 9 compares the mean value from an averaging circuit 8 with a reference value adjusted previously by a variable resistance 10 and the output signal level of the comparator 9 varies from L to H when the surface level is nearly at a position B. The amplitude of a low frequency voltage to the element 4 is freely set and the reference value of the resistance is varied and set to detect the levels of various granular bodies.