To improve combustion efficiency in coal-fired power stations, three critical combustion parameters, relating to the flow of pulverised fuel, need to be known. These a re the solids velocity, the solids distribution and the particle size. Three prototype industrial instruments manufactured by ABB Instrumentation, each of which measure these parameters, are operating at the Scottish Power plant, Methil Power Station. These have been fitted to 14 inch (350 mm) diameter pneumatic conveyors leading to the burners and are successfully completing an extensive series of trials. The instruments are relatively unaffected by the solids distribution within the pipeline.