CSIRO/Novatech Consulting have been developing air purging as a new way of reducing the moisture content of coarse coal products from vibrating basket centrifuges. The process involves injecting a turbulent stream of high velocity air, via an air knife manifold, through the coal bed as it traverses the centrifuge basket. This paper describes the results obtained when the process was trialled in a commercial scale centrifuge, following successful previous bench and pilot scale work reported previously. Five manifolds of different shapes and sizes were tested. The best results were achieved with units of square cross-section, located close to the outlet edge of the basket. Depending on air speed, product moisture was reduced by between 0.7 and 0.9 wt% at a confidence level exceeding 95%. The best results approached closely the 1.0 wt% moisture reduction target which had been adopted as the project objective. Air purging had no significant effect on the content or size distribution of the solids in the centrate. Increasing air speed led to larger moisture reductions. Higher air speeds were needed compared with previous pilot scale work probably due to the thicker beds encountered in the full scale centrifuge. Despite the higher air speed, the actual air usage (cfm/t of coal) was much more efficient at full scale, being less than half that at pilot scale. (C) 2002 Elsevier Science Ltd. All rights reserved.