GB/T 25285.1-2021 PDF EnglishUS$590.00 · In stock · Download in 9 seconds
GB/T 25285.1-2021: Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 25285.1: Historical versions
Similar standardsGB/T 25285.1-2021: Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT25285.1-2021 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 29.260.20 CCS K 35 Replacing GB 25285.1-2010 Explosive atmospheres - Explosion prevention and protection - Part 1.Basic concepts and methodology Issued on. OCTOBER 11, 2021 Implemented on. MAY 01, 2022 Issued by. State Administration for Market Regulation. Standardization Administration of PRC. Table of ContentsForeword... 4 Introduction... 6 1 Scope... 7 2 Normative references... 8 3 Terms and definitions... 9 4 Risk assessment... 15 5 Possible ignition sources... 21 6 Risk reduction... 29 7 Usage information... 52 Appendix A (Informative) Equipment tightness... 54 Appendix B (Informative) Relationship between equipment protection level (EPL) and zones... 57 Appendix C (Normative) Tools for explosive atmospheres... 58 Appendix D (Normative) Verification procedure for ultrasonic threshold limits in liquids... 59 References... 611 ScopeThis document specifies methods for identifying and assessing hazardous situations that may lead to explosions, as well as design and structural measures that are consistent with safety requirements, through the following aspects. - Risk assessment; - Risk reduction. Safety of equipment, protective systems, components can be achieved, by eliminating hazards and/or limiting risks, i.e., by. a) Proper design (no safety protection devices); b) Safety protection devices; c) Usage information; d) Any other precautionary measures. Explosion protection measures corresponding to a) (prevention) and b) (protection) are covered in Chapter 6.Explosion protection measures corresponding to c) are covered in Chapter 7.The explosion protection measures corresponding to d) are not covered in this document. They are covered in GB/T 15706 (Chapter 6 in GB/T 15706-2012). The preventive and protective measures, which are specified in this document, can only provide the required level of protection, when the equipment, protective systems and components are operated within the scope of their intended use and are installed and maintained in accordance with the corresponding operating procedures or requirements. This document specifies general design and manufacturing methods, to help designers and manufacturers achieve explosion-proof safety, when designing equipment, protective systems, components. This document applies to any equipment, protective systems, components, which are intended to be used in explosive atmospheres under atmospheric conditions. These environments may be caused by flammable substances that are handled, used or released by equipment, protective systems, components, OR by flammable substances around equipment, protective systems and components and/or by the constituted materials from which equipment, protective systems, components. This document applies to equipment, protective systems, components at all stages of use. This document applies to category II and category III equipment, which is used in other places except coal mine equipment. For equipment requirements in underground areas of coal mines and coal mine surface facilities, that are dangerous due to gas and/or combustible coal powder, see GB/T 25285.2. This document does not apply to. - Medical equipment for medical environments; - Equipment, protective systems, components used in explosion hazard locations, as caused entirely by the presence of explosive substances or unstable chemicals; - Equipment, protective systems, components in places where explosions are caused by the reaction of substances with oxidants other than oxygen in the atmosphere, OR where explosions are caused by other dangerous reactions or non-atmospheric conditions.2 Normative referencesThe contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, for dated reference documents, only the version corresponding to the date applies to this document; for undated reference documents, the latest version (including all amendments) applies to this document. GB/T 2900.35 Electrotechnical terminology - Equipment for explosive atmospheres GB/T 3836.15 Explosive atmospheres - Part 15.Electrical installations design, selection and erection GB/T 3836.28 Explosive atmospheres - Part 28.Non-electrical equipment for explosive atmospheres - Basic method and requirements GB/T 15706 Safety of machinery - General principles for design - Risk assessment and risk reduction EN 15198 Methodology for the risk assessment of non-electrical equipment and components for intended use in potentially explosive atmospheres3 Terms and definitionsThe terms and definitions, as defined in GB/T 2900.35, as well as the following terms and definitions, apply to this document. 3.1 Flammable substance A substance in gas, vapor, liquid, solid form, or a mixture of these forms, that reacts exothermically with air when ignited. 3.2 Component Devices, that are essential to the safety functions of equipment and protective systems but have no independent function. 3.3 Deflagration An explosion, that travels at subsonic speeds. 3.4 Detonation An explosion, that travels at supersonic speeds and has the characteristics of a shock wave. 3.5 Equipment Machinery, equipment, fixed or mobile devices, control units, instruments, detection or prevention systems, which are used alone or in combination, for the generation, transmission, storage, measurement, control, conversion and/or material processing of energy, AND which can cause explosions due to their own potential ignition sources.4 Risk assessment4.1 General For non-electrical equipment, components, protective systems, devices and their combinations, if they themselves have potential ignition sources and are expected to be used in explosive atmospheres, a risk assessment shall be carried out in accordance with GB/T 3836.28. 4.2 Identification of explosion hazard 4.2.1 General Explosion hazards are often associated with materials and substances that are handled, used or released by equipment, protective systems, components, as well as with the materials from which equipment, protective systems, components are made. Some of these released substances undergo a combustion process in the air. 4.2.2 Combustion characteristics Since the material itself is not used here, but the contact or mixing of dust and air is used to illustrate potential hazards; therefore, it shall determine the characteristics of the mixture of flammable substances and air. 4.2.3 Explosion characteristics The characteristics of explosive atmospheres after ignition shall be described using the following data. 4.2.4 Possibility of hazardous explosive atmospheres The possibility of a hazardous explosive atmosphere occurring depends on the following. 4.3 Identification of ignition hazard 4.3.1 General First, it shall be determined which types of ignition sources are possible and which are associated with the equipment (or components, protective systems). 4.3.2 Ignition characteristics The ignition characteristics of hazardous explosive atmospheres shall be determined. Relevant data such as. 4.3.3 Possibility of effective ignition source Potential ignition sources shall be classified, according to their likelihood of becoming an effective source of ignition, as follows. 4.4 Estimating the possible effects of an explosion In order to estimate the possible effects of an explosion, the following factors need to be considered, such as.5 Possible ignition sources5.1 Hot surfaces If an explosive atmosphere comes into contact with a heated surface, ignition may occur. Not only the hot surface itself can become an ignition source, but also the dust layer and combustible solids that are in contact with or ignited by the hot surface can become an ignition source in explosive atmospheres (see 5.2). 5.2 Flames and hot gases (including hot particles) Combustion reactions at temperatures above 1000 °C are usually accompanied by flames. Hot gases are the products of the reaction; in dusty and/or soot-laden flames, 5.3 Impact, friction, grinding caused by machinery As a result of friction, impact or abrasive processes such as grinding, particles can be produced that are separated from the solid material and heated by the application of energy during the separation process. If these particles contain oxidizable substances, such as iron or steel, they can undergo oxidation processes, that reach higher temperatures. 5.4 Electrical equipment and components Sparks and hot surfaces (see 5.1) of electrical equipment and components can become sources of ignition. Sparks and hot surfaces can be generated under the following conditions. 5.5 Stray current and cathode anti-corrosion measures Stray currents may occur in conductive systems or conductive parts of systems for the following reasons. currents and cathodic corrosion.6 Risk reduction6.1 Basic principles Based on the necessity of the simultaneous existence of a dangerous explosive atmosphere and an effective ignition source, as well as the expected effects of explosions described in Chapter 4, the basic principles of explosion prevention and explosion protection are derived directly in the following order. 6.2 Avoid explosive atmospheres or reduce the amount of hazardous explosive atmospheres 6.2.1 Process parameters 6.2.1.1 Replace or reduce the amount of substances capable of creating an explosive atmosphere 6.2.1.2 Limit concentration If it is unavoidable to handle substances that can form an explosive atmosphere, measures can be taken to control the amount and/or concentration of flammable substances, to prevent or limit the amount of hazardous explosive atmospheres within equipment, protective systems, components. 6.2.2.3 Ventilation and dilution Ventilation is important to control the effects of releases of flammable gases and vapors. It can be used inside and outside equipment, protective systems, components. Note. GB 3836.14 provides relevant content on the use of ventilation, to control and classify gas and vapor hazardous locations. 6.3 Hazardous locations 6.3.1 General Hazardous locations may depend on the design and use of certain equipment, protective systems, components. They shall be taken into account, when planning the design and specified uses (see GB 3836.14 and GB/T 12476.3). 6.7 Principles of measurement and control systems for explosion prevention and protection GB/T 16855.1 covers general principles in this field.7 Usage information7.1 General This Chapter specifies information on use and maintenance, which shall be provided with the equipment, protective systems, components, OR as part of the instructions for use (e.g., user manual). 7.3 Qualifications and training Information on qualifications and training needs shall be provided, to enable users to select competent staff for operations, in locations where explosive atmospheres may occur. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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