In the present study, a new close coupled annular slit type nozzle was designed and constructed to produce metal powders in order to investigate the improvement of efficiency of fine powder production. The atomisation runs for the present study were performed with a small scale close coupled gas atomisation system designed and constructed at the Mechanical Engineering Department of Dumlupinar University. Pure tin powders were produced using nitrogen gas. The effects of the atomisation gas pressure on the backpressure and powder size have been discussed. The present atomisation runs showed that particle size decreased as atomising gas pressure increased. The particle size was reduced from 55.4 to 12.9 mu m with increasing pressure from 0.9 to 3.1 MPa. The mass median particle sizes decreased continuously from 55 mu m at a G/M of 0.22 to 12.9 mu m at a G/M of 1.36 with increasing G/M ratio. Above a certain G/M, the resultant particle sizes cannot be considerably reduced by further increasing atomising pressure.