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GB/T 3836.31-2021 English PDF (GBT3836.31-2021)

GB/T 3836.31-2021 English PDF (GBT3836.31-2021)

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GB/T 3836.31-2021: Explosive atmospheres -- Part 31: Equipment dust ignition protection by enclosure "t"

GB/T 3836.31-2021
ICS 29.260.20
CCS K 35
Replacing GB 12476.5-2013
Explosive atmospheres - Part 31: Equipment dust ignition
protection by enclosure “t”
(IEC 60079-31:2013, NEQ)
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
Introduction ... 6
1 Scope ... 9
2 Normative references ... 9
3 Terms and definitions ... 10
4 General ... 10
5 Construction ... 14
6 Verification and tests ... 17
7 Marking ... 19
Annex A (Normative) Supplementary requirements for entries ... 20
This document is drafted in accordance with GB/T 1.1-2020 "Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents".
This document is Part 31 of GB/T 3836 "Explosive atmospheres". GB/T 3836 has issued the following parts:
- Part 1: Equipment - General requirements;
- Part 2: Equipment protection by flameproof enclosures "d";
- Part 3: Equipment protection by increased safety "e";
- Part 4: Equipment protection by intrinsic safety "i";
- Part 5: Equipment protection by pressurized enclosure "p";
- Part 6: Equipment protection by liquid immersion “o”;
- Part 7: Equipment protection by powder filling “q”;
- Part 8: Equipment protection by type of protection 'n';
- Part 9: Equipment protection by encapsulation 'm';
- Part 11: Material characteristics for gas and vapour classification - Test methods and data;
- Part 12: Material characteristics for combustible dusts - Test methods; - Part 13: Equipment repair, overhaul, reclamation and modification;
- Part 14: Classification of areas - Explosive gas atmosphere;
- Part 15: Electrical installations design, selection and erection;
- Part 16: Electrical installations inspection and maintenance;
- Part 17: Equipment protection by pressurized room “p” and artificially ventilated room “v”;
- Part 18: Intrinsically safe electrical systems;
- Part 20: Equipment with equipment protection level (EPL) Ga;
- Part 21: Application of quality systems for equipment manufacture;
- Part 22: Protection of equipment and transmission system using optical radiation; - Part 23: Group Ⅰ, category EPL equipment intended to remain functional in atmospheres endangered by firedamp and/or coal dust;
- Part 24: Equipment protection by special protection “s”;
- Part 25: Requirements for process sealing between flammable process fluids and electrical systems;
- Part 26: Electrostatic hazards - Guidance;
- Part 27: Electrostatic hazards - Test;
- Part 28: Non-electrical equipment for explosive atmospheres - Basic method and requirements;
- Part 29: Non-electrical equipment for explosive atmospheres - Constructional safety 'c', control of ignition source 'b', liquid immersion 'k'; - Part 30: Equipment and components in explosive atmospheres in underground mines;
- Part 31: Equipment dust ignition protection by enclosure 't';
- Part 32: Intrinsically safe systems with electronically controlled spark duration limitation;
- Part 33: Equipment in adverse service conditions;
- Part 34: Equipment assemblies;
- Part 35: Classification of areas for explosive dust atmospheres.
This document replaces GB 12476.5-2013 "Electrical apparatus for use in the presence of combustible dust - Part 5: Protection by enclosures ‘tD’". Compared with GB 12476.5-2013, the main technical changes are as follows:
- Delete the two types of A and B (see Clauses 5~9 of the 2013 edition); - Introduce three levels of protection of "ta", "tb" and "tc" and their requirements (see Clause 4);
- Change the requirements for construction (see Clause 5; Clauses 4, 6, and 7 of the 2013 edition);
- Change the requirements for verification and tests (see Clause 6; Clause 8 of the 2013 edition);
Explosive atmospheres - Part 31: Equipment dust ignition
protection by enclosure “t”
1 Scope
This document specifies the design, construction, and testing requirements for Ex equipment and Ex Components with dust ignition protection by enclosure “t”. This document is applicable to electrical equipment protected by enclosure and surface temperature limitation for use in explosive dust atmospheres.
This document does not apply to dusts of explosives, which do not require atmospheric oxygen for combustion, or to pyrophoric substances.
This document does not apply to Ex equipment or Ex Components intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust.
This document does not take account of any risk due to an emission of flammable or toxic gas from the dust.
This document is a supplement and modification to the general requirements of GB/T 3836.1. When the requirements of this document conflict with the requirements of GB/T 3836.1, the requirements of this document take precedence.
2 Normative references
The contents of the following documents, through normative references in this text, constitute indispensable provisions of this document. Among them, for dated references, only the edition corresponding to that date applies to this document. For undated references, the latest edition (including all amendments) applies to this document. GB/T 197 General purpose metric screw threads - Tolerances (GB/T 197-2018, ISO 965-1:2013, MOD)
GB/T 3836.1 Explosive atmospheres - Part 1: Equipment - General requirements (GB/T 3836.1-2021, IEC 60079-0:2017, MOD)
GB/T 4208 Degrees of protection provided by enclosure (IP code) (GB/T 4208-2017, IEC 60529:2013, IDT)
GB/T 4942.1 Degrees of protection provided by the integral design of rotating electrical machines (IP code) - Classification (GB/T 4942.1-2006, IEC 60034- 5:2000, IDT)
GB/T 9364 (all parts) Miniature fuses [IEC 60127 (all parts)]
GB/T 9816.1 Thermal-links - Part 1: Requirements and application guide (GB/T 9816.1-2013, IEC 60691:2002, MOD)
ANSI/ASME B1.20.1 Pipe threads, general purpose (inch)
ANSI/UL 248 (all parts) Standard for Low-Voltage Fuses
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1, as well as the following definitions, apply.
Dust ignition protection by enclosure “t”
Type of protection for explosive dust atmospheres where electrical equipment is provided with an enclosure providing dust ingress protection and a means to limit surface temperatures.
4 General
4.1 Levels of protection
Type of protection “t” is divided into three Levels of Protection based on the risk of the Ex equipment becoming an ignition source in an explosive dust atmosphere. The equipment with dust ignition protection by enclosure “t” shall be either: - Level of Protection “ta” (EPL “Da”), or
- Level of Protection “tb” (EPL “Db”), or
- Level of Protection “tc” (EPL “Dc”).
The construction and marking requirements apply to all electrical equipment, and in addition, the requirements for Level of Protection "ta" as given in 4.3 and the requirements for Levels of Protection "tb" and "tc" as given in 4.4.
Failure modes as defined in the relevant industrial standard for particular components shall be taken into account when considering applicable fault conditions.

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