A single-sided centrifugal compressor is to deliver 14 kg/s of air when operating at a pressure ratio of 4:1 and a speed of 200 rev/s. The inlet stagnation conditions may be taken as 288 K and 1.0 bar. Assuming a slip factor of 0.9, a power input factor of 1.04 and an overall isentropic efficiency of 0.80, estimate the overall diameter of the impeller. If the Mach number is not to exceed unity at the impeller tip, and 50 per cent of the losses are assumed to occur in the impeller, find the minimum possible axial depth of the diffuser. [68.9 cm, 5.26 cm]