GB 3836 is composed of the following parts under a general title of Explosive Atmospheres:
——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 Oil-immersion "o";
——Part 7: Equipment Protection by Power Filling “q”;
——Part 8: Equipment Protection by Type of Protection "n";
——Part 9: Equipment Protection by Type of Protection "m";
——Part 11: Equipment Protection by Flameproof Enclosures "d" - Method of Test for Ascertainment of Maximum Experimental Safe Gap;
——Part 12: Classification of Mixtures of Gases or Vapours with Air According to Their Maximum Experimental Safe Gaps and Minimum Igniting Current;
——Part 13: Equipment Repair, Overhaul and Reclamation;
——Part 14: Classification of Areas - Explosive Gas Atmosphere;
——Part 15: Electrical Installations Design, Selection and Erection;
——Part 16: Inspection and Maintenance of Electrical Installation;
——Part 17: Construction and Use of Rooms or Buildings Protected by Pressurization;
——Part 18: Intrinsically Safe System;
——Part 19: Fieldbus Intrinsically Safe Concept (FISCO)
——Part 20: Equipment with Equipment Protection Level (EPL) Ga
…
This part is Part 5 of Explosive Atmospheres.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB 3836.5-2004 Electrical Apparatus for Explosive Gas Atmospheres - Part 5: Pressurized Enclosures "p".
There are the following main technical changes with respect to GB 3836.5-2004:
——"16.10 Temperature measurement" is deleted;
——The term "safety device" is added;
——The concept "equipment protection level (EPL)" is added;
——The requirements of instructions are added (refer to Chapter 19).
This part is modified in relation to IEC 60079-2:2007 Explosive Atmospheres - Part 2: Equipment Protection by Pressurized Enclosure "p" (English version) by redrafting method. There are the following main modifications with respect to IEC 60079-2:2007:
——"e) For type px, when the pressurized enclosure overpressure falls below the minimum value specified by the manufacturer, the electrical supply to automatic safety devices shall be disconnected automatically" is added in 7.9;
——"16.9 Operation infallibility test for automatic safety device" is added.
This part was proposed by the China Electrical Equipment Industrial Association.
This part is under the jurisdiction of National Technical Committee on Explosion Protected Electrical Apparatus of Standardization Administration of China (SAC/TC 9).
The previous editions of the standard replaced by this part are as follows:
——GB 3836.5-1987, GB 3836.5-2004.
Introduction
This part of Explosive Atmospheres specifies the design, construction, testing and marking of electrical apparatus for use in explosive atmospheres in which
a) a protective gas maintained at a pressure above that of the external atmosphere is used to guard against the formation of an explosive gas atmosphere within enclosures which do not contain an internal source of release of flammable gas or vapour and, where necessary;
b) a protective gas is provided in sufficient quantity to ensure that the resultant mixture concentration around the electrical parts is maintained at a value outside the explosive limit appropriate to the particular conditions of use. The protective gas is supplied to an enclosure containing one or more internal sources of release in order to guard against the formation of an explosive gas atmosphere.
This part includes requirements for the apparatus and its associated equipment including the inlet and exhaust ducts, and also for the auxiliary control apparatus necessary to ensure that pressurization and/or dilution is established and maintained.
Explosive Atmospheres - Part 5: Equipment Protection by Pressurized Enclosure "p"
1 Scope
This part of Explosive Atmospheres contains the specific requirements for the construction and testing of electrical apparatus with pressurized enclosures, of type of protection "p", intended for use in explosive gas atmospheres. It specifies requirements for pressurized enclosures containing a limited release of a flammable substance.
This part supplements and modifies the general requirements of GB 3836.1. Where a requirement of this part conflicts with a requirement of GB 3836.1, the requirements of this part take precedence.
This part does not contain the requirements for:
——pressurized enclosures where the containment system may release
a) air with an oxygen content greater than normal, or
b) oxygen in combination with inert gas in a proportion greater than 21%;
——pressurized rooms or analyser houses; see GB 3836.17-2007 and IEC 60079-16.
Note 1: Due to the safety factors incorporated in the type of protection, the uncertainty of measurement inherent in good quality, regularly calibrated measurement equipment is considered to have no significant detrimental effect and need not be taken into account when making the measurements necessary to verify compliance of the equipment with the requirements of this part.
Note 2: When the user acts in the role of the manufacturer, it is typically the user’s responsibility to ensure that all relevant parts of this part are applied to the manufacturing and testing of the equipment.
Note 3: Types of protection "px" and "py" provide Equipment Protection Levels (EPL) Gb or Mb. Type of protection "pz" provides Equipment Protection Level (EPL) Gc. For further information, see Annex H.
2 Normative References
The following referenced documents are indispensable for the application 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 2900.35-2008 Electrotechnical Terminology - Equipment for Explosive Atmospheres (IEC 60050-426:2008, IDT)
GB/T 2900.83-2008 Electrotechnical Terminology - Electrical and Magnetic Devices (IEC 60050-151:2001, IDT)
GB 3836.1-2010 Explosive Atmospheres - Part 1: Equipment - General Requirements (IEC 60079-0:2007, MOD)
GB/T 4207-2012 Method for the Determination of the Proof and the Comparative Tracking Indices of Solid Insulating Materials (IEC 60112:2009, IDT)
GB/T 4208-2008 Degrees of Protection Provided by Enclosure (IP Code) (IEC 60529:2001, IDT)
GB/T 4942.1-2006 Degrees of Protection Provided by the Integral Design of Rotating Electrical Machines (IP Code) - Classification (IEC 60034-5:2000, IDT)
GB/T 16935.1-2008 Insulation Coordination for Equipment within Low-voltage Systems - Part 1: Principles, Requirements and Tests (IEC 60664-1:2007, IDT)
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.35-2008, GB/T 2900.83-2008 and GB 3836.1-2010, as well as the following apply.
Note: Unless otherwise specified, the terms "voltage" and "current" mean the r.m.s. values of an alternating, direct or composite voltage or current.
3.1
alarm
piece of apparatus that generates a visual or audible signal that is intended to attract attention
3.2
containment system
part of the apparatus containing the flammable substance that may constitute an internal source of release
3.3
dilution
continuous supply of a protective gas, after purging, at such a rate that the concentration of a flammable substance inside the pressurized enclosure is maintained at a value outside the explosive limits at any potential ignition source (that is to say, outside the dilution area)
Note: Dilution of oxygen by inert gas may result in a concentration of flammable gas or vapour above the upper explosive limit (UEL).
3.4
dilution area
area in the vicinity of an internal source of release where the concentration of a flammable substance is not diluted to a safe concentration
3.5
enclosure volume
volume of the empty enclosure without internal apparatus. For rotating electrical machines, the free internal volume plus the volume displaced by the rotor
3.6
flammable substance
gases, vapours, liquids or mixtures thereof that are capable of being ignited
3.7
hermetically sealed device
device which is so constructed that the external atmosphere cannot gain access to the interior and in which any seal is made by fusion, for example, brazing, welding or the fusion of glass to metal
3.8
ignition-capable apparatus; ICA
apparatus which in normal operation constitutes a source of ignition for a specified explosive gas atmosphere. This includes electrical apparatus not protected by a type of protection listed in 7.13
3.9
indicator
piece of apparatus that shows whether flow or pressure is adequate and is monitored periodically, consistent with the requirement of the application
3.10
internal source of release
point or location from which a flammable substance in the form of a flammable gas or vapour or liquid may be released into the pressurized enclosure such that in the presence of air an explosive gas atmosphere could be formed
3.11
leakage compensation
providing a flow of protective gas sufficient to compensate for any leakage from the pressurized enclosure and its ducts
3.12
overpressure
pressure above ambient pressure within a pressurized enclosure
3.13
pressurization
technique of guarding against the ingress of the external atmosphere into an enclosure by maintaining a protective gas therein at a pressure above that of the external atmosphere
3.14
pressurization system
grouping of safety devices and other components used to pressurize and monitor or control a pressurized enclosure
3.15
pressurized enclosure
enclosure in which a protective gas is maintained at a pressure greater than that of the external atmosphere
Note: "pressurized enclosure" is deemed as synonymous with "pressurized enclosures".
3.16
protective gas
air or inert gas used for purging and maintaining an overpressure and, if required, dilution
Note: For the purposes of this part, inert gas means nitrogen, carbon dioxide, argon or any gas which, when mixed with oxygen in the ratio 4 parts inert to 1 part oxygen as found in air, does not make the ignition and flammability properties, such as explosive limits, more onerous.
3.17
protective gas supply
compressor, blower or compressed gas container that provides the protective gas at a positive pressure. The supply includes inlet (suction) pipes or ducts, pressure regulators, outlet pipes, ducts, and supply valves. Components of the pressurization system are not included
3.18
purging
in a pressurized enclosure, the operation of passing a quantity of protective gas through the enclosure and ducts, so that the concentration of the explosive gas atmosphere is brought to a safe level
3.19
routine test
test to which each individual device (equipment) is subjected during or after manufacture to ascertain whether it complies with certain criteria
[IEV151-04-16, modified]
3.20
static pressurization
maintenance of an overpressure within a pressurized enclosure without the addition of protective gas in a hazardous area
3.21
type px
pressurization that reduces the equipment protection level within the pressurized enclosure from Gb to non-hazardous or Mb to non-hazardous
3.22
type py
pressurization that reduces the equipment protection level within the pressurized enclosure from Gb to Gc
3.23
type pz
pressurization that reduces the equipment protection level within the pressurized enclosure from Gc to non-hazardous
Foreword i
Introduction iii
1 Scope
2 Normative References
3 Terms and Definitions
4 Protection Types
5 Constructional Requirements for Pressurized Enclosures
6 Temperature Limits
7 Safety Provisions and Safety Devices (Except for Static Pressurization)
8 Safety Measures and Safety Devices Used for Static Overpressure
9 Supply of Protective Gas
10 Pressurized Enclosure with an Internal Source of Release
11 Release Conditions
12 Design Requirements for Containment System
13 Protective Gas and Pressurizing Techniques
14 Ignition-capable Apparatus
15 Internal Hot Surfaces
16 Type Verification and Tests
17 Routine Tests
18 Marking
19 Instructions
Annex A (Normative) Purging and Dilution Tests
Annex B (Informative) Examples of Functional Sequence Diagram
Annex C (Informative) Examples of the Changes in Pressure in Ducts and Enclosures
Annex D (Informative) Information to be Provided to the User
Annex E (Normative) Classification of the Type of Release within Enclosures
Annex F (Informative) Examples for the Use of the Dilution Area Concept
Annex G (Normative) Infallibility Test for Containment System
Annex H (Informative) Introduction of an Alternative Risk Assessment Method Encompassing "Equipment Protection Levels" for Ex Equipment
