Fans Ventilation A Practical Guide

Normal quantities and units used in fan technology

The fan and air movement industries within the English speak­ing world have for many years used a number of specialised units. These have been based on the imperial system, adapted as necessary. Often an arbitrary choice was made, for example pressure measured in inches water gauge. Table 22.11 gives a number of conversion factors designed […]

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Preferred numbers

22.4.1 General Standardisation is necessary if products are to be sold across national frontiers without problems of installation and opera­tion. This applies in particular to dimensions to ensure that products can be purchased to a standard with the knowledge that it will fit in place of the same basic product manufactured by a different company […]

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Other conversion factors

Hardness is not defined within the SI system. The following ta­ble can be used for conversion between the popular systems used. Tensile Strength Vickers hardness (F > 98 N) Brinell Hardness Rockwell hardness N/mm2 HV BHN HRB HRc 200 63 60 210 65 62 220 69 66 225 70 67 230 72 68 Tensile Strength […]

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Conversion factors for SI units

A number of electrical terms evolved from the CGS system may still be encountered as well as units in the FPS system and other special units. In general it is best to convert units to the SI system before inserting quantities into equations as this will avoid problems involving conversion factors in the equations themselves. […]

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SI, The International System of Units

SI, Systиme Internationale d’Unitйs, the international measure­ment unit system, is not a completely new system. It is based on an earlier metric system and is coming more and more into world-wide use. The SI system is now systematically con­structed to cover in practice all scientific, technical and daily re­quirements and is subject to international agreement. […]

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Units, conversions, standards and Preferred numbers

The modern SI system has been adopted in legislation by practically every country in the world. There are, however, extensive changeover problems and many different kinds of data are still only available in units which do not conform to the SI system. Chapter 22 attempts to bridge the difficulties experienced when dealing with quantities expressed […]

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Pneumatic conveying

A conveying system of any kind is used to transport a material from one particular place to another. For the chosen method of pneumatic conveying, air is used as the transport medium. It is Or: VH = where: VH Equ 21.23 Applicable to most granular materials, be they in that form natu­rally or have to […]

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Explosive atmospheres

On the 1st July 2003 the ATEX Directive of the European Union became a part of UK law. Whilst its provisions can, and do, af­fect all equipment used in hazardous areas, this Section con­centrates on its requirements for fans. They are, after all, the prime mover in ventilation and air conditioning systems. Unfortunately there is […]

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Dust and fume extraction

The intention of any local extract system is to reduce what could be a danger due to the pollution of the atmosphere by some me­chanical or chemical process. It is imperative that the contami­nant be captured as close as possible to its source by moving a mass of air across possible escape routes. An alternative […]

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Mechanical draught

Gas, oil and coal fired boilers are used extensively to provide heating, hot water and steam for process applications, and in the generation of electrical power. In all cases where a fuel is being burnt, fans are used to provide combustion air, to trans­port exhaust gases and in some cases used to transport and deliver […]

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