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TM42 Fan application guide (2006)
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TM42 Fan application guide (2006)

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A person's health can be seriously impaired by inadequate ventilation - the quality, temperature and movement of the air. Condensation and the growth of mould is a risk to buildings. Air freshness should be controlled with the removal of odours, pollutants and excessive moisture. The essence of the correct air motion is a matter of identifying the correct system, selecting the correct terminations, controls and duct routing and, perhaps most importantly, selecting the correct fan.

It is a common perception that the fan is simply an air extraction device; a tool to move air between given points, e.g between the bathroom and outdoors. Fans are not only used to enhance personal comfort and well-being. Many uses of fans go unnoticed such as cooling a personal computer or the special fans used to extract hazardous fumes from industrial processes.

This Fan application guide considers the principles of air movement and the various fan types available in order to achieve the best results. The authors are all engineers with considerable experience in the fan industry. They discuss the principles and practice of air extract/supply system design, and offer guidance on fan selection to ensure that such systems perform their intended function efficiently.

This publication has been produced not for the fan engineer but for the engineer who uses fans. It is aimed not only at specifiers, mechanical services designers and architects but also at those responsible for building services and plant maintenance.


1. How a fan works
1.1 Axial fans
1.2 Mixed flow fans
1.3 Centrifugal fans
1.4 Tangential flow fans
1.5 High pressure fans
1.6 Summary of fan types

2. Fan laws and system resistance
2.1 Fan laws
2.2 System resistance laws
2.3 Practical facts of the combined fan and system laws

3. Fan selection
3.1 Fan characteristic curves
3.2 Electrical supply
3.3 Efficiency
3.4 Noise level considerations
3.5 Air performance of different fan types

4. Installation and system effects

5. Fan control
5.1 The need for control
5.2 Savings in fan power
5.3 Sensors and controllers
6. Parallel and series operation
6.1 Parallel operation
6.2 Series operation

7. Acoustics
7.1 Acoustic terms
7.2 Noise level
7.3 Human perception of sound
7.4 Fan manufacturers’ data
7.5 Application and installation effects
7.6 Control of noise

8. Safety and maintenance
8.1 Installation
8.2 Commissioning
8.3 Operation
8.4 Maintenance


Appendix 1: Definitions and explanations
Appendix 2: Airflow and pressure measurement
Appendix 3: Information required for fan selection
Appendix 4: Electric motors



Authors and contributors: Paul Cowell (ebm-papst UK Ltd.); Geoff Lockwood (ebm-papst UK Ltd.); Ron Mulholland (Howden Group Ltd.); Ian Davis (Vortice Ltd.); Colin Biggs (Nuaire Ltd.); Ian Andrews (Nuaire Ltd.); Dan Hopkins (ebm-papst UK Ltd.)

Task Group
Chair: Geoff Lockwood (ebm-papst UK Ltd.)
Members: Ian Andrews (Nuaire Ltd.); Colin Biggs (Nuaire Ltd.); Ken Butcher (CIBSE); Paul Cowell (ebm-papst UK Ltd.); Ian Davis (Vortice Ltd.); Mike Duggan (Federation of Environmental Trade Associations); Neil Jones (Fläkt Woods Ltd.); Ron Mulholland (Howden Group Ltd.)

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