A vibrating-rod level switch specially designed for providing high or low level switching signals in silos or bins containing free-flowing powders and granular materials such as carbon black, sugar, grain, cement, lime, and sand with a material bulk density of 50 kg/m3 or more. These are integral units providing a low cost and reliable level detection of bulk solids in tanks or silos. This is ideally suited for level control on powders, granular or lump materials up to a minimum density of 0,05 kg/dm3.