EN ISO 7726 pdf download – Ergonomics of the thermal environment – Instruments for measuring physical quantities (Iso 7726:1998)

EN ISO 7726 pdf download - Ergonomics of the thermal environment - Instruments for measuring physical quantities (Iso 7726:1998)

EN ISO 7726 pdf download – Ergonomics of the thermal environment – Instruments for measuring physical quantities (Iso 7726:1998).
As the time constant and hence the response time of a sensor does not depend solely on the sensor (mass, surface area, presence of a protective shield) but also on the environment, and hence on factors connected with a given measurement (air velocity, radiation, etc.), at Is necessary to indicate the conditions under which these values were obtained, The standard environmental conditions are specified in table 3 (classes C and S). They shall be used as a reference except where this contradicts the principle for measuflng the quantTties under consideration.
In addition, the accuracy of measurement for air temperatures, mean radiant temperature, radiant temperature asymmetry. air velocity and humidity also depends on the effect of other quantities. Consequently, the accuracy specified in table 2 shall be achieved for the environmental conditions specified in the table.
4.22 CharacteristIcs of Integrating types of measuring Instruments
Any measuring instrument integratrng me measurement of several variables shall have a measuring interval, a response time and an accuracy equal to or better than those of the corresponding individual variables.
5 Specifications relating to measuring methods
5.1 General
The methods for measuring the physical characteristics of the environment shall take account of the fact that these characteristics vary in location and tWie.
The thermal environment may vary with the horizontal location, and then account has to be taken of how long a time
a person is working at the different locations. The environment may also vary In the vertical direction, as shown wi
5.2 SpecifIcations relating to variations In the physical quantities within the space surrounding the subject
An environment may be considered to be “hornogeneous from the bio-ciimatical point of view if, at a given moment, air temperature, radiation, air velocity and humidity can be considered to be practically uniform around the subect, I.e. when the deviations between each of these quantities and their mean spatial value calculated as a mean of the locations does not exceed the values obtained by multiplying the required measuring accuracy from table 2 by the corresponding factor X listed in table 4. This condition is frequently met in the case of air temperature, air velocity and humidity, but more rarely in the case of radiation.
When the envarorwnent is too heterogeneous, the physical quantities shall be measured at several locations at or around the subject and account taken of the partial results obtained in order to determine the mean value of the quantities to be considered in assessing the comfort or the thermal stress. Previous analyses of the thermal stress of the work places being studied or of work places of a similar type may provide information which is of interest in determining whether certain of the quantities are distributed in a homogeneous way. It is usual in the case of poorly defined rooms or work places to consider only a limited zone of occupancy where the criteria of comfort or thermal stress shall be respected. In case of dispute In the interpretation of data, measurements carried Out presuming the environment to be heterogeneous shall be used as a reference.
Table 5 shows the heights to be used for measuring the basIc quantities and the weighting coefficients to be used for calculating the mean values for these quantities according to the type of environment considered and the class of measurement specifications.
The heights to be used for the denved quantities shall preferably be chosen in conformity with the information supplied in table 5. Plane radiant temperature, mean radiant temperature and absolute humidity are normally only measured at the centre height. Reference, however, shall be made to the general standard which defines the stress indices or thermal comfort indices and which takes precedence over this Intemahonal Standard.

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