NF EN ISO 7933

NF EN ISO 7933

February 2005
Standard Cancelled

Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain

ISO 7933:2004 specifies a method for the analytical evaluation and interpretation of the thermal stress experienced by a subject in a hot environment. It describes a method for predicting the sweat rate and the internal core temperature that the human body will develop in response to the working conditions.The various terms used in this prediction model, and in particular in the heat balance, show the influence of the different physical parameters of the environment on the thermal stress experienced by the subject. In this way, this International Standard makes it possible to determine which parameter or group of parameters should be modified, and to what extent, in order to reduce the risk of physiological strains.The main objectives of ISO 7933:2004 are the following:the evaluation of the thermal stress in conditions likely to lead to excessive core temperature increase or water loss for the standard subject;the determination of exposure times with which the physiological strain is acceptable (no physical damage is to be expected). In the context of this prediction mode, these exposure times are called "maximum allowable exposure times".ISO 7933:2004 does not predict the physiological response of individual subjects, but only considers standard subjects in good health and fit for the work they perform. It is therefore intended to be used by ergonomists, industrial hygienists, etc., to evaluate working conditions.

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Main informations

Collections

National standards and national normative documents

Thematics

Sécurité, Silver économie, Gestion des risques et SST, Accessibilité, QSE

Publication date

February 2005

Number of pages

42 p.

Reference

NF EN ISO 7933

ICS Codes

13.180   Ergonomics

Classification index

X35-204

Print number

1 - 03/02/2005

International kinship

ISO 7933:2004

European kinship

EN ISO 7933:2004
Sumary
Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain

ISO 7933:2004 specifies a method for the analytical evaluation and interpretation of the thermal stress experienced by a subject in a hot environment. It describes a method for predicting the sweat rate and the internal core temperature that the human body will develop in response to the working conditions.

The various terms used in this prediction model, and in particular in the heat balance, show the influence of the different physical parameters of the environment on the thermal stress experienced by the subject. In this way, this International Standard makes it possible to determine which parameter or group of parameters should be modified, and to what extent, in order to reduce the risk of physiological strains.

The main objectives of ISO 7933:2004 are the following:

  1. the evaluation of the thermal stress in conditions likely to lead to excessive core temperature increase or water loss for the standard subject;
  2. the determination of exposure times with which the physiological strain is acceptable (no physical damage is to be expected). In the context of this prediction mode, these exposure times are called "maximum allowable exposure times".

ISO 7933:2004 does not predict the physiological response of individual subjects, but only considers standard subjects in good health and fit for the work they perform. It is therefore intended to be used by ergonomists, industrial hygienists, etc., to evaluate working conditions.

Replaced standards (1)
NF EN 12515
September 1997
Standard Cancelled
Hot environments. Analytical determination and interpretation of thermal stress using calculation of required sweat rate.

Le présent document fait partie d'une série de normes qui spécifient des méthodes de mesurage et d'évaluation des ambiances thermiques chaudes, modérées ou froides. Il spécifie une méthode d'évaluation analytique et d'interprétation de la contrainte thermique subie par un sujet en ambiance thermique chaude.

Standard replaced by (1)
NF EN ISO 7933
August 2023
Standard Current
Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain

This document describes a model [the predicted heat strain (PHS) model] for the analytical determination and interpretation of the thermal stress (in terms of water loss and rectal temperature) experienced by an average person in a hot environment and determines the maximum allowable exposure times within which the physiological strain is acceptable for 95 % of the exposed population (the maximum tolerable rectal temperature and the maximum tolerable water loss are not exceeded by 95 % of the exposed people). The various terms used in this prediction model and, in particular, in the heat balance, show the influence of the different physical parameters of the environment on the thermal stress experienced by the average person. In this way, this document makes it possible to determine which parameter or group of parameters can be changed, and to what extent, in order to reduce the risk of excessive physiological strain. In its present form, this method of assessment is not applicable to cases where special protective clothing (e.g. fully reflective clothing, active cooling and ventilation, impermeable coveralls) is worn. This document does not predict the physiological response of an individual person, but only considers average persons in good health and fit for the work they perform. It is therefore intended to be used by, among others, ergonomists and industrial hygienists, as the outcomes can require expert interpretations. Recommendations about how and when to use this model are given in ISO 8025.

Table of contents
  • Avant-propos
    iv
  • Introduction
    v
  • 1 Domaine d'application
    1
  • 2 Références normatives
    1
  • 3 Symboles et termes abrégés
    2
  • 4 Principes de la méthode d'évaluation
    5
  • 5 Principales étapes de calcul
    5
  • 5.1 Équation générale du bilan thermique
    5
  • 5.2 Calcul du flux de chaleur par évaporation requis, de la mouillure cutanée requise et du débit sudoral requis
    7
  • 6 Interprétation du débit sudoral requis
    8
  • 6.1 Base de la méthode d'interprétation
    8
  • 6.2 Analyse de la situation de travail
    8
  • 6.3 Détermination de la durée limite d'exposition admissible, Dlim
    9
  • 6.4 Organisation du travail en ambiance chaude
    9
  • Annexe A (normative) Données nécessaires au calcul du bilan thermique
    10
  • Annexe B (informative) Critères d'estimation de la durée d'exposition admissible dans un environnement de travail chaud
    18
  • Annexe C (informative) Métabolisme énergétique
    20
  • Annexe D (informative) Caractéristiques thermiques de la tenue vestimentaire
    22
  • Annexe E (informative) Programme informatique permettant le calcul du modèle d'astreinte thermique prévisible
    24
  • Annexe F (normative) Exemples de calculs du modèle d'astreinte thermique prévisible
    33
  • Bibliographie
    34
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