BS EN ISO 12759 pdf free download
BS EN ISO 12759 pdf free download.Fans — Efficiency classification for fans.
5 Fan installation, efficiency and tolerance 5.1 General Fans range from the purpose-built single fan to the series-produced certified ranges, which are manufactured in large quantities. A fan can be an impeller on a shaft with no drive mechanism attached (i.e. bare shaft fan) (see Figure 1), or a motor attached to a drive system attached to an impeller within an impeller housing. In that case, it can be supplemented by a volume control, such as a variable speed control or guide vanes (i.e. driven fan) (see Figure 2). The variation in design has led to efficiency being defined in a number of ways to suit the demands of the fan type and the market.5.2 Use of installation categories Fan efficiency ratings are frequently specific for each standardized test installation category. If a fan is designed for a single installation category, its rated efficiency grade shall refer to that particular test installation category, and this shall be clearly identified. If a fan is suitable for use with different installation categories, the fan efficiency grade shall be based on the efficiency ratings referring to the most suitable category, and this shall be clearly identified. To determine the operating point of the fan, four installation categories shall be considered (see Figure 3). For details of test methods, see the following clauses of ISO 5801:2007: a) category A installations — Clause 30; b) category B installations — Clause 31; c) category C installations — Clause 32; d) category D installations — Clause 33. The standardized installation category used for rating the fan shall be clearly stated (see Annex C). The motor input power and motor output power may be measured or determined using the methods given in ISO 5801. Installation category E is not included in this International Standard.5.4 Tolerances At each stage of the fan design and manufacturing cycle, including conversion from prototype performance data or calculation, fabrication and testing of a purpose-designed fan, finite uncertainties prevail and acceptance tolerances shall be applied. Any test for fan performance is subject to error, and the range within which these testing errors can be expected to lie is defined numerically as the uncertainty of measurement. In addition, the true performance of the fan (if it can be ascertained) would be found to differ from that of another nominally identical fan, owing to inevitable variations in manufacture. The expected range of this manufacturing variation shall be added to the uncertainty of measurement to determine the minimum tolerance required for a performance specification. The tolerances given in ISO 13348:2007, Clause 5 (performance tolerances for purpose-designed fans and series-produced non-certified fans), and ISO 13348:2007, Clause 6 (performance tolerances for series- produced fans in certified ratings programmes), shall apply.6 Ratings 6.1 General The variation of fan type and drive option leads to efficiency being derived in different ways. For grading purposes, the efficiency has been defined as a function of the size for bare shaft fans and as a function of input power for driven fans. Direct comparison shall not be made between driven fans rating (FMEG) and bare shaft fans rating (FEG). If the efficiency of the bare shaft fan is required on a driven unit (see 6.2), Figure 4 remains applicable. In this case, the motor efficiency shall be obtained from a dynamometer test or by calibrated motor performance curves, conforming to IEC 60034-2-1. This clause gives guidance on the optimum efficiency (best efficiency point) levels which are achievable by the fan types addressed in this International Standard. The minimum levels of acceptability are dependent on consultation between regulator and manufacturer’s representatives or local legislation, where this exists. The efficiency grade for a fan is based on its performance characteristics at a speed not higher than the maximum safe operating speed to obtain its best efficiency point. BS EN ISO 12759 pdf download.
