SIST EN 27243:2001

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Warmes Umgebungsklima - Ermittlung der Wärmebelastung des arbeitenden Menschen mit dem WBGT-Index (wet bulb globe temperature) (ISO 7243:1989)Ambiances chaudes - Estimation de la contrainte thermique de l'homme au travail, basée sur l'indice WBGT (température humide et de globe noir) (ISO 7243:1989)Hot environments - Estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature) (ISO 7243:1989)13.100Varnost pri delu. Industrijska higienaOccupational safety. Industrial hygieneICS:Ta slovenski standard je istoveten z:EN 27243:1993SIST EN 27243:2001en01-marec-2001SIST EN 27243:2001SLOVENSKI
STANDARD



SIST EN 27243:2001



SIST EN 27243:2001



SIST EN 27243:2001



INTERNATIONAL STANDARD ISO 7243 Second edition 1989-08-01 Hot environments - Estimation of the heat stress on working man, based on the l/VBGT-index (wet bulb globe temperature) Ambiances chaudes - Estima tion de Ia con train te thermigue de l’homme au travail, bade SW l’indice WBGT (tempkature humide et de globe noir) Reference number ISO 7243 : 1989 (El SIST EN 27243:2001



ISO 7243 : 1989(E) IForeword BS0 (the lnternational Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bedies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7243 was prepared by Technical Committee ISO/TC 159, Ergonomics. This second edition cancels and replaces the first edition (ISO 7243 : 19821, of which it constitutes a minor revision. Annexes A to D of this International Standard are for information only. 0 ISO 1989 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronie or mechanical, including photocopying and microfilm, without Permission in writing from the publisher. International Organization for Standardization Case postale 56 l CH-121 1 Geneve 20 l Switzerland Printed in Switzerland ii SIST EN 27243:2001



ISO 7243 : 1989 (El Introduction This International Standard is one study of thermal environments. of a series (listed in annex D) intended for use in the The aim of this series of International Standards is in particular - the finalization of definitions for terms to be used in methods of measurement, test and interpretation, taking into account those Standards already existing or which are being drafted; - the drafting of specifications relating to the methods p hysical Parameters characterizing thermal environments; of measurement for the selection of one or more methods of interpretation of the Parameters; - the establishment of recommended or maximum values for exposure to ther- mal environments in the regions of comfort and extreme environments (hot and cold 1; - the drafting of specifications relating to the methods of measurement of the ef- ficiency of devices or procedures for individual or collective protection against heat and cold. In the light of the increasing interest being shown in the Problems presented by the ex- posure of individuals to thermal environments and the fact that there are few documents or national Standards in this field, it seemed desirable to publish this Inter- national Standard, without waiting for the complete series to be drafted. The wet bulb globe temperature (VOGT) index is one of the empirical indices representing the heat stress to which an individual is exposed. This index is easy to determine in an industrial environment. The method for evaluating the heat stress based on this index is a compromise between the desire to use a very precise index and the need to be able to carry out control measurements easily in an industrial environ- ment. lt should be regarded as an exploratory method. A method of estimating the thermal stress based on an analysis of the heat exchange . between man and environment allows a more accurate estimation of stress and an analysis of the methods of protection. But with the present technology of measure- ment, the method has the drawback of being longer and more difficult to undertake. Such a method will therefore be used either directly when it is desired to carry out an intensive analysis of working conditions in heat, or in addition to the method based on the WBGT index when the values obtained using the first approach exceed the reference values shown. Establishing a method of evaluating heat stress based on the WBGT index is only one step towards the definition of an index showing the advantages of both methods together. However, as there is no such index at present it seemed advisable to en- Courage immediately the development of an International Standard capable of being used in an industrial environment. SIST EN 27243:2001



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INTERNATIONAL STANDARD ISO 7243 : 1989 (E) Hot environments - Estimation of the heat stress on working man, based on the IABGT-index (wet bulb globe temperature) 1 Scope This International Standard gives a method, which tan easily be used in an industrial environment, for evaluating the heat stress to which an individual is subjected in a hot environment and which allows a fast diagnosis. lt applies to the evaluation of the mean effect of heat on man during a period representative of his activity but it does not apply to the evaluation of heat stress suffered during very short periods, nor to the evaluation of heat Stresses close to the zones of comfort. 2 Principle and general definition The heat stress to which a person exposed to a hot environ- ment is subjected is, in particular, dependent on the production of heat inside the body as a result of physical activity and the characteristics of the environment governing heat transfer between the atmosphere and the body. The internal thermal load is the result of metabolic energy caused by activity. A detailed analysis of the influence of the environment on heat stress requires a knowledge of the following four basic Parameters : air temperature, mean radiant temperature, air Speed, and absolute humidityJ1 However, an Overall estima- tion of this influence tan be made by measuring Parameters derived from these basic Parameters and which are a function of the physical characteristics of the space used. The WBGT index combines the measurement of two derived Parameters, natura1 wet-bulb temperature (t,,) and the globe temperature (fg) and in some situations, the measurement of a basic Parameter, air temperature (f,) (dry bulb temperature). The following expressions show the relationship between these different Parameters : - Inside buildings and outside buildings without solar load : WBGT = 0,7 t,, + 0,3 t, - Outside buildings with solar load: WBGT = 0,7 t,, + 0,2 t, + 0,l t, This method of estimating heat stress is based on the measure- ment of these different Parameters and the calculation of mean values taking into account any space-time variations of these Parameters. The data collected and dealt with in this way are compared with the reference values and then it is necessary - either to reduce directly the heat stress or strain at the work-place by appropriate methods; - or to carry out a detailed analysis of the heat stress using methods that are more elaborate but are also usually longer and more difficult to apply. These reference values correspond to levels of exposure to which, under the conditions specified in annex A, almost all in- dividuals tan be ordinarily exposed without any harmful effect, provided that there are no pre-existing pathological conditions. Moreover, the fixing of these levels of exposure in relation to the health of the individual in no way prejudices those which might possibly be fixed for other important reasons such as the alteration of psychosensorimotor reactions likely to Cause ac- cidents at work. 3 Measurement of Parameters characteristic of the environment Measurement of the WBGT index necessitates the measure- ment of two derived Parameters, natura1 wet bulb temperature and globe temperature and the measurement of a basic Parameter, air temperature. 3.1 Measurement of derived Parameters The information supplied by the Sensor for measuring the de- rived Parameters is always dependent on the physical characteristics of the Sensor used, all things being equal. These characteristics are specified in 3.1.1 and 3.1.2. 1 SIST EN 27243:2001



ISO 7243 : 1989 (E) 3.1.1 Natura1 wet bulb temperature Sensor e) Accuracy of measurement : The natura1 wet bulb temperature is the value indicated by a temperature Sensor covered with a wetted wick which is ven- tilated naturally, i.e. placed in the environment under con- sideration without forced Ventilation. The natura1 wet bulb temperature is thus different from the thermo-dynamic temperature determined with a psychrometer. The temperature Sensor shall comply with the following characteristics : - range 20 OC to 50 OC: + 0,5 OC; - range 50 OC to 120 OC: + 1 OC. Any device for measuring the natura1 wet bulb temperature or the globe temperature which, after calibration in the specified measuring ranges, provides results to the same degree of ac- curacy may also be used. a) Shape of the sensitive part of the Sensor: cylindrical. 3.2 Measurement of air temperature b) External diameter of the sensitive part of the Sensor: The air temperature, a basic Parameter, may be measured by 6mm+lmm. any suitable method, whatever the shape of the Sensor used. lt is, however, necessary to comply with the measurement c) Length of the Sensor: 30 mm + 5 mm. precautions relating to air temperature measurement. e) Accuracy of measurement : -t 0,5 OC. d) Measuring range : 5 OC to 40 OC. The air temperature Sensor shall, in particular, be protected from radiation by a device which does not impede the circula- tion of air around the Sensor. The measuring range for the air temperature is 10 OC to 60 OC and the accuracy & 1 OC. f) The whole sensitive part of the Sensor shall be covered with a white wick of a highly water-absorbent material (for example, cotton). g) The support of the Sensor shall have a diameter equal to 6 mm, and 20 mm of it shall be covered by the wick to reduce conduction from the support to the Sensor. h) The wick shall be woven in the shape of a sleeve and shall be fitted over the Sensor with precision. Too tight or too loose a grip is detrimental to the accuracy of measure- ment. 4 Measurement or estimation of metabolic energyl) The quantity of heat produced inside the body is an element of heat stress. lt is therefore essential to determine it in Order to evaluate the latter. Metabolic energy which presents the total quantity of energy consumed inside the body, is a good esti- mation of this for most industrial situations (negligible external werk). i) The wick shall be kept clean. Metabolic rate may be determined j) The lower part of the wick shall be immersed in a reser- voir of distilled water. The free length of the wick in the air shall be 20 mm to 30 mm. - either by measuring the Oxygen consumption of the worker; - or by estimating it from reference tables. k) The reservoir shall be designed in such a way that the temperature of the water inside cannot rise as a result of radiation from the environment. Due to the nature of the WBGT index it is sufficient to estimate the metabolic rate according to the reference tables. 3.12 Globe temperature Sensor The estimation of metabolic rate requires some p ractice and shall preferably be done by individ uals havi ng some experience The globe temperature is the temperature indicated by a temperature Sensor placed in the centre of a globe having the following characteristics : a) Diameter: 150 mm. b) Mean emission coefficient : 0,95 (matt black globe). In this tield. In the absence of an evaluation using reference tables, classification of the activities may be restricted to five main classes, namely : resting, low metabolic rate, moderate metabolic rate, high metabolic rate, very high metabolic rate. Table 1 is intended to facilitate such a classification. The values given have been established for continuous activities. c) Thickness: as thin as possible. d) Measuring range: 20 OC to 120 OC. In case of difficulty in interpreting the data, the metabolic rate considered to be the most accurate is the metabolic rate measured directly on the individual. 1) An International Standard is in preparation. 2 SIST EN 27243:2001



ISO 7243 : 1989 (E) Table 1 - Classification of levels of metabolic rate Value to be used for a mean skin for calculation of Examples surface area mean metabolic rate surface area 1 Low metabolic rate Sitting at ease : light manual work (writing, typing, 65 ...