AS 1076.13-1977

1 - AS 1076.13-1977 SELECTION, INSTALLATION AND MAINTENANCE OF ELECTRICAL APPARATUS AND ASSOCIATED EQUIPMENT FOR USE IN EXPLOSIVE ..
4 - PREFACE
6 - CONTENTS
7 - FOREWORD
8 - CODE
8 - 1 SCOPE
8 - 2 DEFINITIONS
8 - 2.1 Analyzer
8 - 2.2 Area classification
8 - 2.3 Electrical apparatus
8 - 2.4 Enclosure
8 - 2.5 Enclosure group
8 - 2.6 Explosive gas/air mixture
9 - 2.7 Fallible component
9 - 2.8 Flammable
9 - 2.9 Flammable substance
9 - 2.10 Flexible member
9 - 2.11 Grouping of gases and vapours
9 - 2.12 Ignition temperature
9 - 2.13 Instrument
9 - 2.14 Instrument system
9 - 2.15 Means of ignition
9 - 2.16 Protective gas
9 - 2.17 Purge
9 - 2.18 Source of release
9 - 2.19 Temperature class
10 - 2.20 Type of protection
10 - 3 PREVENTION OF EXPLOSION
10 - 3.1 Explosion Probability
10 - 3.2 Achieving Low Explosion Probability
10 - 4 AREA CLASSIFICATION, TEMPERATURE CLASS AND GROUPING OF GASES AND VAPOURS
10 - 4.1 General
11 - 4.2 Area Classifications
11 - 4.3 Considerations Affecting Classification and Extent of Hazardous Areas
11 - 4.3.1 General
11 - 4.3.2 Characteristics of flammable substance
12 - 4.3.3 Grade of source of release
12 - 4.3.4 Quantity and method of release
12 - 4.3.5 Type of ventilation
12 - 4.3.6 Climatic conditions
13 - 4.4 Temperature Class
13 - 4.5 Grouping of Gases/Enclosure Group
14 - 5 INSTRUMENT ENCLOSURES, PROTECTION AND LOCATION
14 - 5.1 Enclosures
14 - 5.2 Explosion Hazards Inside Enclosures
14 - 5.3 Protection
15 - 5.4 Single Enclosure
15 - 5.5 Nested Enclosures
15 - 5.6 Locations
16 - 6 PROTECTION FOR ELECTRICAL INSTRUMENTS NOT CONTAINING A SOURCE OF RELEASE.
16 - 6.1 Type of Protection
16 - 6.1.1 General
16 - 6.1.2 Special protection (Ex s)
16 - 6.1.3 Intrinsic safety (Ex ia and Ex ib)
17 - 6.1.4 Flameproof enclosure (Ex d)
17 - 6.1.5 Pressurized enclosure (Ex p)
18 - 6.1.6 Increased safety (Ex e)
18 - 6.1.7 Encapsulation
18 - 6.1.8 Hermetic sealing (Ex h)
18 - 6.1.9 Type ‘n’ protection (Ex n)
19 - 6.1.10 Restricted breathing (Ex n)
19 - 6.2 Unprotected Electrical Apparatus
19 - 7 ENCLOSED SOURCE OF RELEASE
19 - 7.1 General
19 - 7.2 Type and Extent of Internal Release
20 - 7.3 Combination of Types of Release
20 - 7.3.1 Relevant combinations
20 - 7.3.2 Condition 1 (No normal release, restricted abnormal release)
21 - 7.3.3 Condition 2 (No normal release, unrestricted abnormal release)
21 - 7.3.4 Condition 3 (Limited normal release, restricted abnormal release)
21 - 7.3.5 Condition 4 (Limited normal release, unrestricted abnormal release)
22 - 7.3.6 Condition 5 (Unlimited release)
22 - 7.4 Effect on Area Classification
23 - 8 PROTECTION FOR ELECTRICAL INSTRUMENTS CONTAINING A SOURCE OF RELEASE.
23 - 8.1 Types of Enclosure
23 - 8.2 Flameproof Enclosure
23 - 8.3 Pressurized and Continuously Diluted Enclosures
25 - 8.4 Other Enclosures
26 - 9 SELECTION OF A TYPE OF PROTECTION
26 - 9.1 General
26 - 9.2 Use of Table 1
26 - 9.3 Use of Table 2
27 - 9.4 Examples
27 - 9.4.1 Example 1
30 - 9.4.2 Example 2
30 - 9.4.3 Example 3
31 - 9.4.4 Example 4
32 - 10 INSTALLATION
32 - 10.1 General
32 - 10.2 Permanent Wiring
32 - 10.2.1 Type of cable
33 - 10.2.2 Avoidance of damage
33 - 10.2.3 Avoidance of the transmission of flammable substances
33 - 10.2.4 Cable glands, terminal boxes and junction boxes
34 - 10.2.5 Earthing
34 - 10.3 Circuit Protection.
34 - 10.4 Installation of Intrinsically Safe Instrument Systems
35 - 11 INSPECTION, TESTING AND MAINTENANCE
35 - 11.1 General
35 - 11.2 Isolation
35 - 11.3 Insulation Testing
36 - 11.4 Testing of Intrinsically Safe Instrument Systems
36 - 11.4.1 Functional testing
36 - 11.4.2 Validity testing
36 - 11.5 Alterations
37 - APPENDIX A - LIST OF RELATED PUBLICATIONS

Provides recommendations for the selection, installation and use of instruments and instrument systems utilizing electrical energy in hazardous areas or in the proximity of flammable substances. It deals exclusively with protection against hazards arising from explosive mixtures caused by release of flammable substances. It does not deal with hazards arising from dust flyings and fibres, increased hazards arising from oxygen-enriched atmospheres, or highly specialized hazards such as those arising from radio-induced sparks.

This Part of the code gives recommendations for the selection, installation and use of instruments and instrument systems utilizing electrical energy in hazardous areas or in the proximity of flammable substances.It also takes into account that for certain instruments the release of flammable substances may be internal as well as external to the enclosure. Consequently, this results in combinations of area classification, types of release and types of protection not previously covered.This Part deals exclusively with protection against hazards arising from explosive mixtures, resulting from release of flammable substances. It does not deal with hazards arising from dust fibres and flyings, increased hazards arising from oxygen-enriched atmospheres, or highly specialized hazards such as those arising from radio-induced sparks.Outlines of area classification, types of release and types of protection are principally based upon the recommendations published in AS 1076, Parts 1 and 2,* to which reference should be made for detailed information.