GB/T 3836.11-2022Explosive atmospheres - Part 11: Material characteristics for gas and vapour classification - Test methods and data (English PDF)

Foreword

This document was drafted in accordance with the rules given in GB/T 1.1-2020

"Directives for standardization - Part 1.Rules for the structure and drafting of

standardizing documents".

This document is Part 11 of GB/T 3836 "Explosive atmospheres". The following parts

of GB/T 3836 have been issued.

- 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 liquid immersion "o"

- Part 7.Equipment protection by powder filling "q"

- Part 8.Equipment protection by type of protection "n"

- Part 9.Equipment protection by encapsulation ''m''

- Part 11.Material characteristics for gas and vapour classification - Test methods

and data

- Part 12.Material characteristics for combustible dusts - Test methods

- Part 13.Equipment repair, overhaul, reclamation and modification

- Part 14.Classification of hazardous areas

- Part 15.Electrical installations design, selection and erection

- Part 16.Electrical installations inspection and maintenance

- Part 17.Equipment protection by pressurized room ''p'' and artificially ventilated

room ''v''

- Part 18.Intrinsically safe electrical systems

- Part 20.Equipment with equipment protection level (EPL) Ga

- Part 21.Application of quality management systems for Ex Product manufacture

- Part 22.Protection of equipment and transmission system using optical radiation

- Part 23.Group I, category EPL equipment intended to remain functional in

atmospheres endangered by firedamp and/or coal dust

- Part 24.Equipment protection by special protection ''s''

- Part 25.Requirements for process sealing between flammable process fluids and

electrical systems

- Part 26.Electrostatic hazards - Guidance

- Part 27.Electrostatic hazards - Test

- Part 28.Non-electrical equipment for explosive atmospheres - Basic method and

requirements

- Part 29.Non-electrical equipment for explosive atmospheres - Constructional

safety ''c'', control of ignition source ''b'', liquid immersion ''k''

- Part 30.Equipment and components in explosive atmospheres in underground

mines

- Part 31.Equipment dust ignition protection by enclosure "t"

- Part 32.Intrinsically safe systems with electronically controlled spark duration

limitation

- Part 33.Equipment in adverse service conditions

- Part 34.Equipment assemblies

- Part 35.Classification of areas for explosive dust atmospheres

- Part 36.Electrical safety devices for the control of potential ignition sources from

Ex Equipment.

This document replaces GB/T 3836.11-2017 "Explosive atmospheres - Part 11.

Material characteristics for gas and vapour classification - Test methods and data".

Compared with GB/T 3836.11-2017, in addition to the structural adjustments and

editorial changes, the main technical changes in this document are as follows.

- the range that needs to simultaneously determine the maximum test safety gap and

the minimum ignition current ratio is changed (see 4.2, 4.3 of this Edition, 4.4 of

Edition 2017);

- cases where classification should not be based on similarity in chemical structure

are added (see 4.4 of this Edition);

- the requirements for the short-circuit current of the ignition device and the

requirements for the spark discharge time are added (see 6.3.4 of this Edition);

- the requirements for the autoignition temperature test device are changed (see 7.2

of this Edition, 7.2 of Edition 2017);

- the sampling, preparation and storage requirements for auto-ignition temperature

test specimens are added (see 7.3 of this Edition);

- the procedures for auto-ignition temperature test are changed (see 7.4 of this

Edition, 7.3 of Edition 2017);

- the criterion for the validity of auto-ignition temperature test results is changed (see

1 Scope

This document specifies the test methods and classification principles for determining

the maximum experimental safe gaps (MESG) of gas-air mixtures or vapour-air

mixtures under normal temperature and pressure conditions (20°C, 101.3kPa).

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.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-426

and the following apply.

classification system of equipment related to the explosive atmosphere for which they

are intended to be used

4 Classification of gases and vapours

Mixtures of gases should generally be allocated to an equipment group only after a

special determination of MESG or MICR ratio. One method to estimate the equipment

group is to determine the MESG of the mixture by applying a form of Le Châtelier's

principle.

5 Data for flammable gases and vapours, relating to the use of equipment

Determinations have been made by a number of different methods, but the preferred

method is with a low energy ignition at the bottom of a vertical tube. The values (in

percentage by volume and mass per volume) are listed in Table B.1.

6 Method of test for the maximum experimental safe gap (MESG)

The apparatus is described in the following subclauses 6.2.1 ~ 6.2.7 and is shown

schematically in Figure 1.It is also possible to use an automatic set-up when it is proven

that the same results are obtained as with a manual apparatus.

7 Method of test for auto-ignition temperature (AIT)

The test vessel shall be a 200 mL narrow-necked Erlenmeyer flask made of borosilicate

glass according to ISO 1773.It shall be ensured that the inner surface of the bottom is

flat. A clean flask shall be used for tests.

Annex A

(normative)

Ovens of test apparatus for the tests of auto-ignition temperature

Ovens constructed in accordance with A.2 and A.3 are suitable for the tests described

in Clause 7.

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