On this page we have attempted to demonstrate how the direction of air flow created by a fan may be changed by the manner in which it is fitted to a motor shaft.
Remember, fans are normally described as being Clockwise or Anti-clockwise. The easy way to tell which rotation fan you have is to lay it on a flat surface with one blade approximately at 12 o’clock. If the right hand edge of that blade is touching the table, then it is a Clockwise fan. If the left hand edge of the fan touches the table, then it is an Anti-clockwise fan. Turning the fan over makes no difference to which edge touches the table.
For one piece fans we show below four illustrations showing the air flow direction for both clockwise and anti-clockwise fans fitted to motors both with clockwise and anti-clockwise rotation, looking on the shaft end.
Remember also that a fan runs correctly when the concave sides of the fan blades are facing the direction of rotation. |
Below we show the same relationships demonstrated above, but for fans with hubs. Here, when describing a fan requirement, it is useful also to add whether the fan is fixed to the motor shaft with the fan hub to the front, ie. on the opposite side of the fan to the motor, or with the fan hub to the rear, ie. on the same side of the fan as the motor.
The same rules for clockwise and anti-clockwise fans apply as on the previous page. |
