An experimental facility to investigate co-firing requires handling pulverised coal and biomass fuels, to deliver them to a well-instrumented experimental burner in a precise and flexible manner. A system based on loss-in-weight mass flow metering has been successfully used to deliver continuously a wide range of flows of diverse fuels with great accuracy, even in the presence of refill cycles. To achieve the required performance the system must be well-engineered, and in particular the implementation of an appropriate control strategy is essential.