爆炸性环境 第10-2部分：区域分类 爆炸性粉尘环境

[中文适用范围]： IEC 60079-10-2 标准旨在识别和划分存在爆炸性粉尘大气环境及可燃性粉尘沉积层的场所，以便对这类场所中的点火源进行恰当评估。该标准将爆炸性粉尘大气环境与可燃性粉尘沉积层分别讨论：第 4 章描述爆炸性粉尘云的场所划分，并将粉尘沉积层视为可能的释放源之一；第 7 章则阐述针对粉尘沉积层的其他一般性考虑事项。本文中的示例均基于工厂已实施有效的清洁管理措施，以防止粉尘沉积层积聚的情况。若缺乏有效清洁管理，则场所划分需考虑由粉尘沉积层可能形成爆炸性粉尘云的情形。当存在可燃纤维或飞散物可能引发危险时，亦可参照本标准的原则执行。大气条件包括压力与温度相对于参考值（101.3 kPa 或 1 013 mbar，20 °C 或 293 K）的上下波动，只要此类波动对可燃物料的爆炸性能影响可忽略不计。对于含氧量正常的空气，通常假定其体积分数为 21%。本标准不适用于以下情况：a) 地下采矿区域；b) 无需大气氧即可燃烧的爆炸性粉尘，如自燃物质、推进剂、烟火药剂、弹药、过氧化物、氧化剂、遇水反应元素或化合物，以及其他类似物料；c) 超出本标准所述条件的灾难性失效或罕见故障；d) 用于医疗用途的房间；e) 住宅场所；f) 危害源于可燃气体或蒸气存在的情形，但其原则可用于评估混合混合物（另见 IEC 60079-10-1）。本标准不考虑火灾或爆炸后次生损害的影响。有关与上一版相比的重大技术变更的详细列表，请参阅文件前言。 [外文原描述]： IEC 60079-10-2 is concerned with the identification and classification of areas where explosive dust atmospheres and combustible dust layers are present in order to permit the proper assessment of ignition sources in such areas. In this document, explosive dust atmospheres and combustible dust layers are treated separately. In Clause 4, area classification for explosive dust clouds is described, with dust layers acting as one of the possible sources of release. In Clause 7, other general considerations for dust layers are described. The examples in this document are based on a system of effective housekeeping being implemented in the plant to prevent dust layers from accumulating. Where effective housekeeping is not present, the area classification includes the possible formation of explosive dust clouds from dust layers. The principles of this document can also be followed when combustible fibres or flyings might cause a hazard. Atmospheric conditions include variations in pressure and temperature above and below reference levels of 101,3 kPa (1 013 mbar) and 20 °C (293 K), provided that the variations have a negligible effect on the explosive properties of the combustible material. For air with normal oxygen content, typically a volume fraction of 21 % is assumed. It does not apply to: a) underground mining areas; b) dusts of explosives that do not require atmospheric oxygen for combustion such as pyrophoric substances, propellants, pyrotechnics, munitions, peroxides, oxidizers, water‑reactive elements or compounds, or other similar materials; c) catastrophic failures or rare malfunctions which are outside the conditions dealt with in this document; d) rooms used for medical purposes; e) domestic premises; f) where a hazard is due to the presence of flammable gas or vapour, but the principles can be used in the assessment of a hybrid mixture (see also IEC 60079-10-1). This document does not consider the effects of consequential damage following a fire or an explosion. Please refer to the foreword of the document for a detailed listing of the significant technical changes from the previous edition.