IEC 60721-3-3:2002 pdf download

IEC 60721-3-3:2002 pdf download.Classification of environmental conditions -Part 3-3: Classification of groups of environmentalparameters and their severities –
Stationary use at weatherprotected locations.
c) for conditions of smoke and chemically active substances:
— optical density (table 11);
— concentration of hydrogen chloride (table 12).
All the parameters listed contribute towards a description of the environmental fire conditions. Some of the parameters specify fire exposure characteristics. This applies to the classes of table 9 concerning the reaction to fire of materials and products during the pre-flashover fire condition, and to the parameters connected to the classes of table 10 with respect to the fire behaviour and resistance of, for instance, load-supporting and separating structures, doors, ventilation systems during the post.flashover fire condition. Without being direct fire exposure characteristics, parameters such as the heat release ratio of the classes in table 9 and the times in table 8 are decisive for the risk of flashover and, if flashover occurs, for the safe escape of people from the fire. The gas temperatures of the classes of table 9 and the parameters of tables 11 and 12 are all fire exposure characteristics of importance for the functioning of optical detectors and for the probability of people to survive during evacuation or to remain within safe areas of refuge during the fire. The concentration of hydrogen chloride resulting from a fire is important for evaluating the risk of contamination of electric products by subsequent corrosion
6 Sets of environmental condition class combinations
As indicated in clause 5 the classification allows a number of possible combinations of environmental conditions bearing on products wherever used. The number of possibilities, and thus the flexibility, is therefore very great. In practice, however, this flexibility is not always an advantage when, for instance, environmental condition specifications for a certain location are drawn up by different parties, invariably producing small but disturbing divergencies.
In order to limit the possibilities to general cases, standard sets of class combinations may be selected from table 7. For a given location or product, reference may then be made to this standard, for example 1E32. Only when conditions are not considered to be covered by this specification, is reference made to each class as indicated in clause 5. Alternatively, if some seventies of parameters deviate from that or those of the class combination, this should be expressed by the addition to the set designation of the following phrase: “but … (parameter)
(severity and unit)”, for example 1E32 but sand 30 mg/rn3.
Annex D gives a summary of conditions covered by the sets of class combinations.
A.1 General
In this annex the basis of the classes is explained. It gives a survey of conditions affecting the choice of environmental parameters and their seventies, and it contains a summary of the conditions covered by each class.
A.2 Survey of conditions
For each environmental parameter the various possible conditions, which will result in different levels of environmental conditions, are presented. The conditions are arranged in order of increasing seventies.
The first column of the tabulated subclauses A.2.1 to A.2.5 describes the conditions. In the vertical columns headed “Class, an x indicates the conditions covered by the class. The lowest class covering a certain condition may be found by reading horizontally from that condition to the first x encountered.
The procedure of finding an appropriate class as described above is valid for all the subclauses, but A.2.1 contains the additional factor of type of climate given in columns 2 to 10, to which attention has to be paid.
The lowest class covering a certain condition can thus be found by reading vertically down to the relevant type of climate column to the first x in the horizontal line of the relevant condition, then reading horizontally to the right to the first x encountered as previously described.
The types of climate are described in IEC 60721-2-1. and are:
Extremely Cold (except the Central Antarctic)
Cold
Cold Temperate
Warm Temperate
Warm Dry
Mild Warm Dry
Extremely Warm Dry
Warm Damp
Warm Damp, Equable
It should be noted that, if a certain condition referred to in this annex is covered by a certain class, it does not necessarily mean that the class describes, for each single parameter. the lowest environmental severity needed to cover the condition.