GB 12476.1-2013Electrical apparatus for use in the presence of combustible dust -- Part 1: General requirements (English PDF)

Foreword

All the technical contents in this Part are mandatory.

GB 12476 consists of the following parts under the general title Electrical Apparatus

for Use in the Presence of Combustible Dust.

--- Part 1.General Requirements;

--- Part 2.Selection and Installation;

--- Part 3.Classification of Areas where Combustible Dusts are or May be Present;

--- Part 4.Protection by Intrinsic Safety "iD";

--- Part 5.Protection by Enclosures "tD";

--- Part 6.Protection by Encapsulation "mD";

--- Part 7.Type of Protection "pD";

--- Part 8.Test Methods – Methods for Determining the Minimum Ignition

Temperature of Dust;

--- Part 9.Test Methods – Methods for Determining the Electrical Resistivity of Dust

in Layers;

--- Part 10.Test Methods – Methods for Determining Minimum Ignition Energy of

Dust/Air Mixtures.

This Part is Part 1 of GB 12476.

This Part was drafted as per the rules specified in GB/T 1.1-2009.

This Part uses re-drafting method to modify and adopt IEC 61241-0.2004 Electrical

Apparatus for Use in the Presence of Combustible Dust – Part 0.General

Requirements (English Edition I). However, this Part is not the modification in a full

meaning of GB 12476.1-2000.The major technical contents of GB 12476.1-2000 are

replaced by GB 12476.5-2013 Electrical Apparatus for Use in the Presence of

Combustible Dust – Part 5.Protection by Enclosures "tD".

Technically, this Part has the following technical differences and causes with IEC

61241-0.2004.

--- Taking into account the difference BETWEEN the type approval of the inspection

and certification of explosion-proof electrical equipment in China AND the IEC

international standard (there is no provision on the approval procedure), the type

approval procedure for explosion-proof electrical equipment in China is the

explosion-proof certification system. Therefore, the inspection procedure for

obtaining the explosion-proof certificate has been added to any Clause on

manufacturer's responsibility, see Appendix A.

This Part was proposed by China Electrical Equipment Industrial Association.

This Part shall be under the jurisdiction of National Technical Committee for

Standardization of Explosion Protected Electrical Apparatus (SAC/TC 9).

Drafting organizations of this Part. Nanyang Explosion Protected Electrical Apparatus

Research Institute; and China National Quality Supervision and Test Center for

Explosion Protected Electrical Products.

Chief drafting organizations of this Part. CZ Explosion-Proof Electrical Appliances Co.,

Ltd.; Dianguang Explosion-Proof Technology Co., Ltd.; Warom Group Co., Ltd.;

Nanyang Explosion Protection Group Co., Ltd.; Xinliming Explosion Prevention Electric

Appliances Co., Ltd.; Shanghai Baolin Explosion-Proof Electric Co., Ltd.; and Zhejiang

Chuangxin Electric Machine Co., Ltd.

Chief drafting staffs of this Part. Wu Jianguo, Huang Jianfeng, Shi Xiaoxian, Li Jiang,

Bai Zhaohao, Zheng Zhenxiao, Wen Zhenke, Li Shuchao, and Chen Rui.

The historical edition replaced by this Standard is as follows.

--- GB 12476.1-2000.

1 Scope

This Part of GB 12476 specifies general requirements for the design, construction,

testing and marking of electrical apparatus protected by any recognized safeguard

technique for use in areas where combustible dust may be present in quantities that

could lead to a fire or explosion hazard.

2 Normative References

The following documents are essential to the application of this document. For the

dated documents, only the versions with the dates indicated are applicable to this

document; for the undated documents, only the latest version (including all the

amendments) are applicable to this document.

GB/T 70.1-2008 Hexagon Socket Head Cap Screws (ISO 4762.2004, MOD)

GB/T 1040.2-2006 Plastics - Determination of Tensile Properties - Part 2.Test

Conditions for Molding and Extrusion Plastics (ISO 527-2.1993, IDT)

3 Terms and Definitions

For the purposes of this Part, the following terms and definitions apply.

Dust, fibers or flying that can burn or glow in air and could form explosive mixtures with

air at atmospheric pressure and normal temperatures.

Mixture with air, under atmospheric conditions, of flammable substances in the form of

dust, fibers or flying in which, after ignition, combustion spreads throughout the

unconsumed mixture.

4 Construction

Electrical apparatus for use in potentially explosive dust atmospheres shall comply with

the requirements of this standard.

Enclosures for use in Zone 20 or 21 which can be opened more quickly than the time

necessary.

5 Temperatures

For electrical apparatus, the maximum surface temperature shall be specified in

relevant documentation according to 23.2.

In addition to the maximum surface temperature required in 5.1, the maximum surface

temperature may be stated for a given depth of layer, TL, of dust surrounding all sides

of the apparatus, unless otherwise specified in the documentation, and marked

according to 29.2.1h).

6 Enclosure Materials

The following requirements apply to non-metallic enclosures and non-metallic parts of

enclosures on which the type of protection depends.

Materials used in the construction of enclosures of electrical apparatus to be used in

explosive dust atmospheres shall not contain, by weight, more that 7.5 % in total of

magnesium and titanium.

Threaded holes in enclosures for fasteners which secure covers intended to be opened

in service for adjustment, inspection and other operational reasons may only be tapped

in the material of the enclosure when the thread form is compatible with the material

used for the enclosure.

7 Fasteners

Parts necessary to achieve a standard type of protection or used to prevent access to

uninsulated live parts shall be capable of being released or removed only with the aid

of a tool.

Fastening screws for enclosures of materials containing light metals may be made of

light metal or plastics if the material of the fastener is compatible with that of the

enclosure.

8 Interlocking Devices

Interlocking devices used to maintain a type of protection shall be so constructed that

their effectiveness cannot readily be defeated by the use, for example, of a screwdriver

or pliers.

9 Bushings

Bushings in enclosures used as connection facilities and which may be subjected to a

torque while the connection or disconnection is being made shall be mounted in such

a way that all parts are secured against turning.

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