This standard specifies the evaluation method of the heat load of hot working environment and hot working personnel. This standard is applicable to the evaluation of the average heat load of 8h working day, not applicable to the evaluation of the heat load of less than 1h working. GB/T 17244-1998 Evaluation of the heat load of workers in thermal environment based on WBGT index (wet bulb globe temperature) GB/T17244-1998 Standard download decompression password: www.bzxz.net
This standard specifies the evaluation method of the heat load of hot working environment and hot working personnel. This standard is applicable to the evaluation of the average heat load of 8h working day, not applicable to the evaluation of the heat load of less than 1h working.

GB/T17244—1998
This standard is equivalent to ISO7243:1989 "Evaluation of the thermal load of workers in thermal environment based on the WBGT index (wet bulb black globe temperature)".
This standard is one of the series of standards for evaluating thermal environment formulated by the Environmental Subcommittee of ISO/TC159/SC5 Technical Committee for Ergonomics Standardization. This standard uses the WBGT index to evaluate the thermal load of hot working environment and hot working workers. The unit of energy metabolism rate in this standard, according to the requirements of hygiene, lists the "Watt (W)\converted to\ kilocalories (kcal) or dry coke (KJ)" in ISO7243 at the same time, and expresses it in metabolic rate to exclude differences caused by factors such as gender, age, and weight. The calculation method of average energy metabolism rate is not clearly specified in ISO7243. We supplement it. The WBGT index in ISO7243 only specifies the index temperature limit according to the intensity of physical work. On this basis, this standard divides the thermal environment evaluation standard into four levels, namely good, medium, poor and very poor. The index temperature limit specified in ISO7243 is the "good" level, and the index temperature is reduced by one level for every 1°C increase. In addition, some changes have been made in the text and layout. Appendix A, Appendix B and Appendix C of this standard are all prompt appendices. This standard was proposed by the State Administration of Technical Supervision. This standard is under the jurisdiction of the National Technical Committee for Ergonomics Standardization. This standard was jointly drafted by the China Institute of Standardization and Information Classification and Coding, the Institute of Labor Health and Occupational Diseases of the Chinese Academy of Preventive Medicine, and the Beijing Institute of Labor Health and Occupational Diseases. The main drafters of this standard are: Yu Yongzhong, Hua Donghong, Li Tianlin, Xiao Hui, and Jin Shuxiang. 396
GB/T17244—1998
ISOForeword
This international standard is one of a series of standards for the study of thermal environments. The purpose of this international standard is to:
- Review the definitions of terms mentioned in the measurement methods, tests and annotations in the thermal environment standards; draft instructions for the measurement methods of the physical parameters of the thermal environment; select one or more methods for interpreting these parameters; - Determine the recommended values ​​or maximum values ​​of thermal contact in the comfortable environment area and the hot or cold environment area; - Draft instructions for the measurement methods of the effectiveness of individual or collective heat or cold protection measures. In view of the growing interest in the problem of human thermal contact and the lack of documents and national standards in this field, it is necessary to publish this international standard before a complete set of standards is promoted. The wet bulb black globe temperature (WBGT) index is an empirical index that represents the heat load that an individual is exposed to. The index is easy to measure in an industrial environment. The measurement method of the heat load index is a compromise between accurate measurement and convenient factory measurement. Evaluating heat loads based on the analysis of heat exchange between people and the environment makes the evaluation of heat loads and the analysis of protective measures more accurate. However, based on existing technical conditions, this method is complex and difficult to implement. Therefore, heat exchange analysis is only used when direct and accurate analysis of working conditions is required, or when the newly measured values ​​exceed the listed parameter values ​​in addition to the method based on the WBGT index.
Developing the WBGT index heat load measurement method is only a step in determining an index that takes into account the advantages of both methods. Since such an index does not exist at present, efforts should be made to establish an international standard that can be used in industrial environments as soon as possible. 397
National Standard of the People's Republic of China
Hot environments-Estimation of the heat stress on working man based on the WBGT-index (wet bulb globe temperature)1Scope
This standard specifies the evaluation method of hot working environments and hot working personnel's heat load. GB/T 17244—1998
eqv ISO 7243: 1989
This standard is applicable to the evaluation of the average heat load of an 8-hour working day, and is not applicable to the evaluation of the heat load of a work period of less than 1 hour. 2 Definitions
This standard adopts the following definitions.
2.1 WBGT index wet bulb globe temperature indexWBGT refers to the wet bulb globe temperature, which is a basic parameter for the comprehensive evaluation of the heat load of the working environment in which the human body is exposed, and the unit is degree. It is used to evaluate the average heat load of the human body. It uses the natural wet bulb temperature (tnw) and the globe temperature (tg), and the air dry bulb temperature (t.) is measured in the open air. The WBGT index is calculated according to formula (1) and formula (2): 1. No solar radiation indoors and outdoors:
WBGT = 0. 7tnw + 0. 3tg
Solar radiation outdoors:
WBGT = 0. 7tnw + 0. 2tg + 0. 1ta2.2 Heat stress
refers to the degree of heat exposure of the human body when working in a hot environment, expressed as the WBGT index, which depends on the heat production of physical labor and the characteristics of heat exchange between the environment and the human body.
2.3 Mean energy metabolic rate means the average of the total energy consumption of one or more workers in an 8-hour working day, expressed in kcal/min·m2 or kJ/min·m2. 3 Evaluation criteria
The evaluation criteria are expressed in the WBGT index. According to the changes in the WBGT index, the evaluation standards for the thermal environment are divided into four levels (see Table 1).
Average energy
Metabolic rate grade
Approved by the State Administration of Technical Supervision on March 10, 1998398
WBGT index evaluation standard
WBGT index, ℃bzxz.net
Implementation on October 1, 1998
Average energy
Metabolic rate grade
GB/T 17244—1998
Table 1 (Complete)
WBGT index, C
Note: The "good" grade WBGT index value in Table 1 is limited to the maximum rectal temperature not exceeding 38℃ 4 Measurement of environmental meteorological conditions
4.1 Measurement of meteorological parameters
The data measured by a thermometer often depends on the physical properties of the thermometer. The test conditions should comply with the relevant provisions of 4.1.1 and 4.1.2. 4.1.1 Natural wet-bulb temperature
Natural wet-bulb temperature is measured using a wet-bulb thermometer. The temperature-sensing part of the thermometer is wrapped with a layer of wet gauze and allowed to evaporate naturally (without external force). Therefore, the natural wet-bulb temperature is different from the wet-bulb temperature of a ventilated wet-dry thermometer. The thermometer should have the following characteristics:
a) Shape of the temperature-sensing part of the thermometer: cylinder; b) Outer diameter of the temperature-sensing part of the thermometer: 6mm±1mm; c) Length of the temperature-sensing part of the thermometer: 30mm±5mm; d) Measuring range: 5℃～40℃;
e) Measuring accuracy: ±0.5℃C;
f) The temperature-sensing part of the thermometer should be completely covered with white moisture-absorbing material (such as cotton cloth); g) The diameter of the thermometer protective cover should be 6mm, and 20mm of the protective cover must be wrapped with wet gauze to reduce heat transfer from the protective cover to the thermometer;
h) The wet gauze should be woven into a sleeve shape and fixed snugly to the temperature-sensing part. Too tight or too loose will affect the accuracy of measurement; i) The gauze should be kept clean;
i) The lower end of the gauze should be immersed in a tank filled with distilled water, and the length of the end of the gauze exposed to the air should be 20mm to 30mm; k) The water tank should be designed so that the water temperature in it will not rise due to the surrounding radiant heat. 4.1.2 Black ball temperature
The black ball temperature is the temperature indicated by placing a thermometer in the middle of the black ball. The black ball should have the following characteristics:
a) Diameter: 150 mm;
b) Average emissivity: 0.95 (matte black ball); c) Thickness: should be as thin as possible;
d) Measuring range: 20℃～120℃;
e) Measurement accuracy:
-20℃～50℃: ±0.5℃;
-50℃~120℃: ±1℃.
4.2 Measurement of air temperature
When measuring air temperature, it must be noted that the temperature sensing part of the air thermometer should have a device to prevent the influence of radiant heat, and should not hinder the circulation of air in the temperature sensing part. The measurement range should be between 10℃ and 60℃, with an accuracy of ±1℃. 399
5 Measurement or estimation of energy metabolism
GB/T 17244—1998
The heat generated in the body is a component of the heat load, so it is necessary to measure it in order to evaluate the heat load. Energy metabolism is the basic method for estimating the heat load of workers. The metabolic rate can be measured by the following methods:
Measure the oxygen consumption of workers;
-Or estimate from a reference table.
The metabolic rate estimated from the reference table is fully applicable to the WBGT index. The metabolic rate should be estimated by workers with certain practical experience.
If there is no energy metabolism reference table, labor can be divided into five levels: rest, low metabolic rate, medium metabolic rate, high metabolic rate and extremely high metabolic rate, see Table 2. Each activity in the example is a single operation, not the average energy metabolism rate of various activities of one or more people in an 8-hour workday.
Table 2 Energy metabolism rate classification
O Rest
1 Low metabolic rate
2 Medium metabolic rate
3 High metabolic rate
4 Extremely high metabolic rate
W/m Body surface area
M≤65
65
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