ABSTRACT
A Geiger-type detector is typically used for simple on-off level switches. For continuous level measurements, more stable scintillation counters are preferable. Air must be injected continuously, even if the level measurements are not required, as the nozzles can become blocked by particle intrusion. If the aim of the level measurements is to determine the powder content of a storage vessel, a weighing method is preferable. A high-powered laser is used to obtain the surface profile of a powder bed in a storage vessel. The laser beam scans the surface of the powder bed, and the trajectory of the light on the surface is recorded by a highly sensitive camera. When a microwave is transmitted toward a powder bed, part of the wave is reflected by the surface of the powder bed and detected by a sensor on the level meter.
