DIN Standards Committee Mechanical Engineering
DIN EN ISO 5801
Industrial fans - Performance testing using standardized airways (ISO 5801:2007, including Cor 1:2008); German version EN ISO 5801:2008
Industrieventilatoren - Leistungsmessung auf genormten Prüfständen (ISO 5801:2007, einschließlich Cor 1:2008); Deutsche Fassung EN ISO 5801:2008
Overview
This standard contains the German version of EN ISO 5801:2009 which has been prepared by Technical Committee ISO/TC 117 "Fans" of the European Committee of Standardization (CEN). The secretariat is held by the BSI, United Kingdom. The national interests during the preparation of this standard were represented by Technical Section Air handling technology of the Mechanical Engineering Standards Committee (NAM) at DIN. This International Standard deals with the measurements of the performance of fans of all types except those designed solely for air circulation, for example, ceiling fans and table fans. Estimates of uncertainty of measurement are provided and rules for the conversion, within specified limits, of test results for changes in speed, produced gas and, in the case of model tests, size, are given. This International Standard is the result of almost 30 years of discussion, comparative testing and detailed analyses by leading specialists from the fan industry and research organizations throughout the world. It was demonstrated many years ago that the codes for fan performance testing established in different countries do not always lead to the same results. The need for an International Standard has been evident for some time and Technical Committee ISO/TC 117 started its work in 1963. Important progress has been achieved over the years and, although the International Standard itself was not yet published, the successive revisions of various national standards led to much better agreement among them. It has now become possible to complete this International Standard by agreement on certain essential points. It must be borne in mind, however, that the test equipment, especially for large fans, is very expensive. That is why it was necessary to include in this International Standard many setups from various national codes in order to authorize their future use. This explains the sheer volume of this document. Essential features of this International Standard are as follows: a) Categories of installation Since the connection of a duct to a fan outlet or inlet modifies its performance, it has been agreed that four standard installation categories should be recognized (see 18.2). A fan adaptable to more than one installation category will have more than one standardized performance characteristic. Users should select the installation category closest to their application. b) Common parts The differences obtained by testing the same fan according to various test codes depend chiefly on the flow pattern at the fan outlet and, while often minor, can be of substantial significance. There is general agreement that it is essential that all standardized test airways to be used with fans have common parts adjacent to the fan inlet and/or outlet sufficient to ensure consistent determination of fan pressure. Geometric variations of these common parts are strictly limited. However, an agreement has been achieved for particular situations: 1) For fans where the outlet swirl is less than 15°, for instance, centrifugal, cross-flow or vane-axial fans, it is possible to use a simplified outlet duct without straightener when discharging to the atmosphere or to a measuring chamber. If there is any doubt about the degree of swirl, then a test should be performed to establish how much is present. 2) For large fans (outlet diameter exceeding 800 mm), it may be difficult to carry out the tests with standardized common airways at the outlet including a straightener. In this case, by mutual agreement between the parties concerned, the fan performance may be measured using a duct of length 3D on the outlet side. Results obtained in this way may differ to some extent from those obtained using the normal category D installation, especially if the fan produces a large swirl. Establishment of a possible value of differences, is still a subject of research. c) Calculations Fan pressure is defined as the difference between the stagnation pressure at the outlet of the fan and the stagnation pressure at the inlet of the fan. The compressibility of air must be taken into account when high accuracy is required. However, simplified methods may be used when the reference Mach number does not exceed 0,15. A method for calculating the stagnation pressure and the fluid or static pressure in a reference section of the fan, which stemmed from the work of the ad hoc group of Subcommittee 1 of ISO/TC 117, is given in Annex C. Three methods are proposed for calculation of the fan power output and efficiency. All three calculation methods give very similar results (difference of a few parts per thousand for pressure ratios equal to 1,3). d) Flow rate measurement Determination of flow rate has been completely separated from the determination of fan pressure. A number of standardized methods may be used.
