Fans Ventilation A Practical Guide

The integrity of fan data

Where comparisons of fan efficiency are to be made, it is es­sential that all data is the result of tests. These should be con­ducted to the same standard and test method. Individual wit­nessed tests are usually only possible after manufacture is complete and are very expensive. The purchaser should seri­ously consider if certified ratings in […]

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Whose responsibility?

A measure which has been introduced in legislation by a num­ber of countries is to limit the value of Watts/litre/sec for the fans in a particular building. It is usual to take the total flow of air — supply or extract, whichever is the greater—and divide this into the total installed motor power. The value […]

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Other considerations in fixed output systems

Almost without exception, both fans and motors can be made more efficient in large sizes. Where a number of units have to run continuously, consideration should be given to providing a manifold or plenum to couple up the duct systems and use one common fan/motor unit. Even allowing for the additional duct resistance, power savings […]

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Partial optimisation

The two major costs for many fan plants are the costs of ducting on the investment side and the energy costs on the operational side. The investment costs increase with increased duct diam­eter whilst at the same time operational costs decrease, see Figure 19.7. The total costs curve represents a minimum for a certain duct […]

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Important system characteristics

Introduction A = It is important to remember that the fan and its system have to be in balance. Thus if the system resistance has been over or under estimated, the absorbed fan power will vary according to its type. This in turn will affect the losses in the transmission mo­tor and controls. Overall fan […]

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Equ 19.7 Investment calculation — existing plant

Present capitalised value method Where Qv Pf Or For existing plant the question is often asked if an improvement of the plant can reduce the operational costs in such a way as to reduce the whole-life costs. According to the present capital­ised value method the summation of the savings during the ser­vice life will be […]

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Economic assessment

Investment calculation — new plant Present capitalised value method The ventilation plant whole-life cost KL can be calculated as the sum of the investment cost K| and the capitalised operational costs KDcap- The operational costs must be paid annually and therefore be summated to a capitalised present value. This is carried out with the aid […]

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Economic optimisation

Present and impending legislation, as well as a greener ap­proach from us all, dictate that fans and their systems shall be­come more efficient. This Chapter is intended to remind fan en­gineers and their customers of the fundamentals. Without consideration for the fan system and the way in which the flowrate must be controlled (see Chapter […]

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Fan economics

Economic optimisation, both for new and existing fan ventilation systems is discussed in this Chapter. Emphasis is given to the need for considering the complete ventilation system, including the secondary costs of carrying out such an optimisation. Usually it is the ducting system cost and the energy cost which are the two most important factors […]

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Spare parts

When buying fans, it is important to check the manufacturer’s ability to maintain a stock of spare parts. The supplier should be able to provide a quotation for • commissioning spares, • spares for 1 year, • spares for 2 years, • insurance spares. Spares quotations will include delivery times. The spares quoted will be […]

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