# What is pitch of a fan blade?

## What is pitch of a fan blade?

Blade pitch is the angle, measured in degrees, between a 180-degree horizontal plane and a ceiling fan’s blade tilt. The angle of the blade makes a difference in how much air a fan can circulate throughout a room. The optimal blade pitch for a ceiling fan is 12-15 degrees.

### How is fan blade pitch calculated?

Position one blade so that it is in a horizontal position. Place protractor head across concave face of blade at tip and measure pitch angle from 90°. Position successive blades at this same spot and check each pitch angle. See figures on reverse side.

What is the best angle for a fan blade?

The angles of your ceiling fan blades should be set to a minimum of 12 degrees for maximum cooling. You can adjust them to a larger degree, but any angle above 16 degrees may blow around loose objects.

Does the number of blades on a fan matter?

Fans with more blades are known to be quieter than those with fewer blades. Further, fans with more blades tend to be better balanced and less ambient noise. Consider the size of your space and your needs when you choose your fan.

## What RPM should a ceiling fan be?

Customers looking at fan speed should check the fans RPM (Rotations per minute of the blades). The standard 1200 mm (48) fan, runs at 300/350 RPM while the Hi-Speed fan runs at 380/390 RPM or so. Ideally, a ceiling fan should be about 7-9 feet off the ground.

### What are variable-pitch axial flow fans?

Variable-pitch axial flow fans are used for VAV air conditioning systems. The pitch angle of the blades are varied through a controller, e.g., a pneumatic actuator, with increasing blade angle for increasing flow rates and vice versa for reducing flow rates. The characteristics for a typical fan are given in Fig. 15.6. Fig. 15.6.

What is axial flow fan?

4.12. Axial flow fan. In a typical axial fan, the effective progress of the air is straight through the impeller at a constant distance from the axis. The primary component of blade force on the air is directed axially from inlet to outlet and thus provides the pressure rise by a process that may be called direct blade action.

Directly driven axial flow fans have their motors in the airstream, which can be both an advantage and disadvantage. Whilst the moving air cools the motor, if there is high temperature or corrosive elements present, then it is desirable for the motor to be outside.

## How does an aerodynamic fan work?

As the blade moves the air, the aerodynamicmoment acts to turn the blade to a lower pitch. The hub spring creates an opposing momentto hold the blade in position. This is afail-safe mechanism. If air pressure on thediaphragm fails, the fan operates as a fixed-pitch fan providing the maximum designairflow.