Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

• the most efficient way to navigate the Engineering ToolBox!

# Belt driven Fans - Fan vs. Motor Speed

Belt driven fans are used in heating, ventilation, air-conditioning and cooling (HVAC) systems.

The speed of a fan wheel versus the speed of the motor with a belt drive can be calculated as

df nf = dm nm                          (1)

where

df = pulley diameter fan (inch, mm)

nf = speed of fan (rpm - rounds per minute)

dm = pulley diameter motor (inch, mm)

nm = speed of motor (rpm - rounds per minute)

### Example - Speed of Fan

A synchronous electrical motor rotates with speed 1000 rpm. The motor pulley diameter is 76.5 mm and the fan pulley diameter is 205.5 mm. The speed of the fan can be calculated by modifying (1) to

nf = dm nm / df

- or with values:

nf = (76.5 mm) (1000 rpm) / (205.5 mm)

= 372 rpm

## Related Topics

### • Ventilation

Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

## Related Documents

### Belt Transmissions - Speed and Length of Belts

Calculate length and speed of belt and belt gearing.

### Efficiency of Small Machine Elements

Friction and efficiency in bearings and roller chains.

### Fan Motors - Starting Torques

The motor must be capable of accelerating the fan wheel to it's operating speed.

### Fans - Troubleshooting

Guide to troubleshooting fan problems.

### Motors - Speed vs. Pulley Diameter

Pulley (Sheave) selection charts for motors ranging 850 - 3450 rpm.

### Pulleys

Pulleys, blocks and tackles.

## Search Engineering ToolBox

• the most efficient way to navigate the Engineering ToolBox!

## SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!