These metering devices are used to measure the flow rate of very fine particles like fly ash, cement etc. The material flows by gravity through an air slide and flows over a plate which measures the impact which is proportional to the density of the material and the flow rate. The impact on the plate is measured by two high precision loadcells that give a very linear output proportional to the flow rate. The output of the loadcells are fed into the micro controller based flow rate indicator which gives the rate and totalized quantity of material.