GB/T 3836.28-2021 Explosive atmospheres—Part 28：Non-electrical equipment for explosive atmospheres—Basic method and requirements English
1 Scope
This document specifies the basic method and requirements for design, construction, testing and marking of non-electrical equipment for explosive atmospheres.
This document is applicable to non-electrical Ex equipment, Ex Components, protective systems, devices and assemblies of these products that have their own potential ignition sources and are intended for use in explosive atmospheres.
Hand tools and manually operated equipment without energy storage are excluded from the scope of this document. This document does not address the safety of static autonomous process equipment when it is not part of equipment referred to in this document.
Note 1: Static autonomous process equipment includes items such as tanks, vessels, fixed pipework and hand operated valves which do not have their own source of energy that could create a potential ignition source during operation.
This document does not specify requirements for safety, other than those directly related to the risk of ignition which may then lead to an explosion.
The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under which it may be assumed that Ex equipment can be operated are:
——Temperature: -20℃ to +60℃;
——Pressure: 80kPa to 110kPa;
——Air with normal oxygen content, typically 21% v/v.
Such atmospheres can also exist inside the equipment. In addition, the external atmosphere can be drawn inside the equipment by natural breathing produced as a result of fluctuations in the equipment’s internal operating pressure, and/or temperature.
Note 2: Although the standard atmospheric conditions above give a temperature range for the atmosphere of -20℃ to +60℃, the normal ambient temperature range for the Ex equipment is -20℃ to +40℃, unless otherwise specified and marked. It is considered that -20℃ to +40℃ is appropriate for most Ex equipment and that to manufacture all equipment to be suitable for a upper ambient temperature of 60℃ would place unnecessary design constraints.
Note 3: The requirements of this document can also be helpful for the design, construction, testing and marking of equipment intended for use in atmospheres outside the validity range stated above. In this case however, the ignition hazard assessment, ignition protection provided, additional testing (if necessary), manufacturer’s technical documentation and instructions to the user, clearly demonstrate and indicate the equipment’s suitability for the conditions it may encounter. It is also recognized that changes in temperature and pressure can have a significant influence on characteristics of the explosive atmosphere, such as ignitability.
This document specifies the requirements for the design and construction of equipment, intended for explosive atmospheres in conformity with all Equipment Protection Levels (EPLs) of Group I, II and III.
Note 4: It is not unusual for equipment designed and constructed in accordance with this document for a particular EPL to be used in areas requiring an EPL with a higher level of safety by including the application of additional measures. Such measures include for example inerting, suppression, venting or containment or for example by dilution, drainage, monitoring and shut-down. Such measures are outside the scope of this document.
This document supplements and modifies the general requirements of GB/T 3836.1-2021, as shown in Table 1. Where a requirement of this document conflicts with a requirement of GB/T 3836.1-2021, as far as applicable for non-electrical equipment, the requirement of this document takes precedence.
This document is supplemented or modified by the following standards concerning specific types of protection:
——GB/T 3836.29 Explosive atmospheres - Part 29: Non-electrical equipment for explosive atmospheres - Constructional safety "c", control of ignition source "b", liquid immersion "k";
——GB/T 3836.2 Explosive atmospheres - Part 2: Equipment protection by flameproof enclosures "d";
——GB/T 3836.5 Explosive atmospheres - Part 5: Equipment protection by pressurized enclosure "p";
——GB/T 3836.31 Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t".
The nature and ignition sources of non-electrical equipment shall be considered when applying types of protection "d", "p", or "t" on non-electrical equipment (see Annex A).
Table 1 Applicability of specific clauses of GB/T 3836.1-2021
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2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3836.1-2021 Explosive atmospheres - Part 1: Equipment - General requirements (IEC 60079-0:2017, MOD)
GB/T 3836.2 Explosive atmospheres - Part 2: Equipment protection by flameproof enclosures “d” (GB/T 3836.2-2021, IEC 60079-1:2014, MOD)
GB/T 3836.5 Explosive atmospheres - Part 5: Equipment protection by pressurized enclosure “p” (GB/T 3836.5-2021, IEC 60079-2:2014, MOD)
GB/T 3836.22 Explosive atmospheres - Part 22: Protection of equipment and transmission system using optical radiation (GB/T 3836.22-2017, IEC 60079-28:2006, MOD)
GB/T 3836.29 Explosive atmospheres - Part 29: Non-electrical equipment for explosive atmospheres - Constructional safety “c”, control of ignition source “b”, liquid immersion “k” (GB/T 3836.29-2021, ISO 80079-37:2016, MOD)
GB/T 3836.30 Explosive atmospheres - Part 30: Equipment and components in explosive atmospheres in underground mines (GB/T 3836.30-2021, ISO/IEC 80079-38:2016, MOD)
GB/T 3836.31 Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure “t” (GB/T 3836.31-2021, IEC 60079-31:2013, NEQ)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1-2021 as well as the following apply.
3.1
ignition source scenarios
3.1.1
possible ignition source
type of ignition source to be considered for the identification of ignition hazards
Note 1: Possible ignition sources include:
——Hot surfaces;
——Flames and hot gases (including hot particles);
——Mechanically generated sparks;
——Electrical source;
——Stray currents, cathodic corrosion protection;
——Static electricity;
——Lightning;
——Radio frequency (RF) electromagnetic waves from 104 Hz to 3×1011 Hz;
——Electromagnetic waves including optical radiation from 3×1011 Hz to 3×1015 Hz;
——Ionizing radiation;
——Ultrasonics;
——Adiabatic compression and shock waves;
——Exothermic reactions, including self-ignition of dusts.
Note 2: See also Annex B for information of possible ignition sources.
Note 3: See Figure 1.
3.1.2
equipment related ignition source
possible ignition source which could be caused by the equipment under consideration regardless of its ignition capability
Note 1: These are sometimes called "relevant ignition sources". However, this can lead to misunderstanding as to whether the ignition source is relevant in terms of it being present, in terms of its ignition capability or in terms of whether it is present in the equipment or not.
Note 2: All equipment related ignition sources are considered in the ignition hazard assessment to determine whether they are potential ignition sources.
Note 3: See Figure 1.
3.1.3
potential ignition source
equipment related ignition source which has the capability to ignite an explosive atmosphere (i.e. to become effective ignition source)
Note: The likelihood of becoming effective ignition source determines the EPL (they may arise in normal operation, expected malfunction, rare malfunction).
3.1.4
effective ignition source
potential ignition source which is able to ignite an explosive atmosphere when consideration is taken of when it occurs (i.e. in normal operation, expected malfunction or rare malfunction)
Foreword III Introduction VIII 1 Scope 2 Normative references 3 Terms and definitions 4 EPL and equipment groups 4.1 Equipment protection level (EPL) 4.2 Group I equipment 4.3 Group II equipment 4.4 Group III equipment 4.5 Equipment for specific explosive gas atmospheres 5 Ignition hazard assessment 5.1 General requirements 5.2 Ignition hazard assessment procedure 6 Assessment of possible ignition sources and control means 6.1 General 6.2 Hot surfaces 6.3 Flames and hot gases (including hot particles) 6.4 Mechanically generated sparks and hot surfaces 6.5 Electrical ignition sources except stray current 6.6 Stray currents, cathodic corrosion protection 6.7 Static electricity 6.8 Adiabatic compression and shock waves 6.9 Exothermic reactions, including self-ignition of dusts 7 Additional considerations 7.1 Deposits of dust and other material in the gap of moving parts 7.2 Deposits of dust and other material in the flame arresters incorporated in the equipment 7.3 Opening times of enclosures 7.4 Non-metallic enclosures and non-metallic parts of the equipment 7.5 Removable parts 7.6 Materials used for cementing 7.7 Light transmitting parts 7.8 Stored energy 8 Verification and tests 8.1 General 8.2 Determination of the maximum surface temperature 8.3 Mechanical tests 8.4 Additional tests of non-metallic parts of the equipment relevant for type of protection 9 Documentation 9.1 Technical documentation 9.2 Conformity with the documentation 9.3 Certificate 9.4 Responsibility for marking 10 Instructions 11 Marking 11.1 Location 11.2 General 11.3 Warning markings 11.4 Marking on very small equipment 11.5 Examples of marking Annex A (Normative) Protection concepts of types of protection "d", "p” and "t" acceptable for non-electrical equipment Annex B (Informative) Explanation of the ignition hazard assessment procedure Annex C (Informative) Relationship between equipment protection levels (EPLs) and zones Annex D (Informative) Methodology for confirming the EPL Annex E (Informative) Consideration of misuse which can reasonably be anticipated during ignition hazard assessment procedure Annex F (Informative) Examples of ignition hazard assessment Annex G (Informative) Volume dependence of auto-ignition temperature Annex H (Informative) Development of different types of incendive electrostatic discharges Bibliography
