AS 2430.1-1987

1 - AS 2430.1-1987 CLASSIFICATION OF HAZARDOUS AREAS - EXPLOSIVE GAS ATMOSPHERES
4 - PREFACE
4 - CONTENTS
5 - FOREWORD
6 - 1 SCOPE.
6 - 2 APPLICATION
6 - 3 REFERENCED DOCUMENTS
6 - 4 DEFINITIONS
6 - 4.1 Area, hazardous
6 - 4.2 Area, non-hazardous
6 - 4.3 Authority, Statutory
6 - 4.4 Boiling point
6 - 4.5 Explosive gas atmosphere
6 - 4.6 Explosive limit, lower (LEL)
6 - 4.7 Explosive limit, upper (UEL)
6 - 4.8 Flammable gas or vapour
7 - 4.9 Flammable liquid
7 - 4.10 Flammable material
7 - 4.11 Flammable mist
7 - 4.12 Flashpoint
7 - 4.13 Normal operation
7 - 4.14 Relative density (of a gas or vapour)
7 - 4.15 Source of release
7 - 4.16 Ventilation, general artificial
7 - 4.17 Ventilation, local artificial
7 - 4.18 Ventilation, natural
7 - 4.19 Ventilation, no
7 - 4.20 Zones, hazardous
7 - 4.21 Zone 0
7 - 4.22 Zone 1
7 - 4.23 Zone 2
7 - 5 GENERAL
7 - 6 BASIC PRINCIPLES
7 - 6.1 Fundamental safety concepts
8 - 6.2 Factors which determine type and extent of zones
8 - 6.2.1 Type of zone
8 - 6.2.2 Extent of zone
8 - 6.3 Grading of source of release (see also Appendix A)
9 - 7 DETERMINATION OF THE TYPE AND EXTENT OF ZONES
9 - 7.1 General
9 - 7.2 Open air unrestricted ventilated situations
9 - 7.2.1 Procedure
9 - 7.2.2 Quantity of flammable material
9 - 7.2.3 Sources of release graded `continuous'
10 - 8 VENTILATION
10 - 8.1 General
10 - 8.2 Natural ventilation
10 - 8.3 General artificial ventilation
10 - 8.4 Local artificial ventilation
10 - 8.5 No ventilation
10 - 8.6 Relationships between grades of source of release, ventilation and type and extent of zone
10 - 8.6.1 Natural and general artificial ventilation
10 - 8.6.2 Local artificial ventilation
11 - 8.6.3 No ventilation
11 - 8.6.4 Ventilation restricted by obstacles
11 - 8.6.5 Consequences of artificial ventilation failure
11 - 9 PROPERTIES OF FLAMMABLE LIQUIDS, GASES AND VOLATILE SOLIDS.
12 - APPENDIX A - SOURCES OF RELEASE
12 - A1 SCOPE.
12 - A2 GRADES OF SOURCES OF RELEASE
12 - A2.1 General
12 - A2.2 Continuous grade source of release
12 - A2.3 Primary grade source of release
12 - A2.4 Secondary grade source of release
12 - A3 EXAMPLES OF SOURCES OF RELEASE
12 - A3.1 General
12 - A3.2 Continuous grades of release
12 - A3.3 Primary grades of release
12 - A3.4 Secondary grades of release

Provides a classification of areas according to the likely existence of an explosive gas/air mixture, including areas in which the mixture is continuously present or present for long periods (Zone 0), areas in which the mixture is likely to occur in normal operation (Zone 1), and areas in which the mixture is not likely to occur or will exist for only a short time (Zone 2). Basic principles involved in classification are given and the factors to be considered in determining the type and extent of zones are described. Similar to IEC 79-10 in terminology, definitions and general treatment of the subject.

This standard provides guidance for the classification of hazardous areas according to the existence of or likelihood of the existence of an explosive gas/air mixture.NOTE: Areas classified as Zones 0, 1 or 2 in accordance with this standard are sometimes referred to as Class I areas.It applies to open and enclosed areas, in all above-ground situations, where there may be a risk due to the presence of flammable gas or vapour mixed with air under normal atmosphere conditions (see Note 1).This standard does not apply to -(a) underground workings including coal mining; (b) processing and manufacture of explosives;(c) areas which may be affected by oxygen enrichment;(d) areas where risks may arise due to the presence of combustible dusts (see Note 3); or(e) potential catastrophic failures such as the bursting of pressure vessels, pipelines or tanks.NOTES:1. Normal atmospheric conditions include variations above and below reference levels of 101.3 kPa and 20C provided the variations have a negligible effect on the explosion properties of the flammable materials.2. The design, construction and installation of plant and equipment have a significant bearing on classification. However, this standard does not specify any requirements for such design, construction or installation.3. The classification of hazardous areas where combustible dusts are present (Class II areas) is covered in AS 2430, Part 2.

Under revision See DR 99254