Particulate emissions from cement kilns have been reduced significantly over the last few decades due in part to ever-tightening regulatory controls including the lowering of emission limit values (ELVs) and the associated increase in installations of highly effective filtration systems which require higher quality monitoring.

During the unloading of limestone powder, silo vehicles are pressurised to the required level using compressed air units controlled by the driver and conveyed to the appropriate silo. Prompt detection of the empty state of the silo vehicle was not possible, therefore, product transfer was often finished too early or unnecessarily long, costing time and excessive use of compressed air.