This part of GB 3836 contains the specific requirements for the construction and testing of electrical apparatus with pressurized enclosures, of protection type "p", intended for use in explosive gas atmospheres, and the requirements contained in this part are supplementary to those in GB 3836.1.
This part specifies requirements for pressurized enclosures containing a limited release of a flammable substance.
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%.
This part does not contain requirements for pressurized rooms or analyser houses.
2 Normative References
The following standards contain provisions which, through reference in this part of GB 3836, constitute provisions of this part. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this part are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to this part.
GB/T 2900.1-1992 "Electrotechnical Terminology-Fundamental Terms" (eqv IEC 60050)
GB/T 2900.35-1998 "Electrotechnical Terminology-Electrical Apparatus for Explosive Atmospheres" (neq IEC 60050(426):1990)
GB 3836.1-2000 "Electrical Apparatus for Explosive Gas Atmospheres-Part 1: General Requirements" (eqv IEC 60079-0:1998)
GB/T 4207-1984 "Method for Determining the Comparative and the Proof Tracking Indices of Solid Insulating Materials under Moist Conditions" (neq IEC 60112:1979)
GB 4208-1993 "Degrees of Protection Provided by Enclosure (IP Code)" (eqv IEC 60529:1989)
GB/T 4942.1-2001 "Classification of Degrees of Protection Provided by Enclosures for Rotating Machines" (idt IEC 60034-5:1991)
GB/T 16935.1-1997 "Insulation Coordination for Equipment within Low-voltage Systems-Part 1: Principles Requirements and Tests" (idt IEC 60664-1:1992)
3 Terms and Definitions
For the purposes of this part, the terms and definitions given in GB/T 2900.1 and GB/T 2900.35 and 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.
