Radial tipped blades

The radial tipped blade design is represented diagrammatically in Figure 1.69.

Radial tipped blades

Figure 1.68 Backplated paddle impellers

This blade form is used as an alternative to the shrouded radial. Generally there is an increased number of blades and the heel of these is forward curved to reduce shock losses. The effi­ciency and flowrate are therefore improved for a given size, but the characteristics are otherwise similar. Fan static efficiencies up to 73% are possible.

Radial tipped blades

The units are widely used for induced draught on water tube boilers where low efficiency dust collectors are incorporated. Dust burdens similar to those of the shrouded radial, in Section

1.5.4 are acceptable.

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