GB/T 3836.18-2024Explosive atmospheres - Part 18: Intrinsically safe electrical systems (English PDF)

Foreword

This document was drafted in accordance with the provisions of GB/T 1.1-2020

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

standardizing documents".

This document is Part 18 of GB(/T) 3836 "Explosive atmospheres". GB(/T) 3836 has

published the following parts:

- Part 1: 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 vapor 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 locations - Explosive atmospheres;

- 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 Ma 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 3836.18-2017 "Explosive atmospheres - Part 18:

Intrinsically safe electrical systems". Compared with GB/T 3836.18-2017, in addition

to structural adjustments and editorial changes, the main technical changes are as

follows:

- CHANGE the content of the system description file (see Chapter 4; Chapter 4 of

the 2017 edition);

- CHANGE the requirements for categories and temperature groups, including the

original Chapter 7 ambient temperature ratings (see Chapter 5; Chapters 5 and 7 of

the 2017 edition);

Explosive atmospheres - Part 18: Intrinsically safe electrical

systems

1 Scope

This document specifies special requirements for the design, structure, and assessment

of intrinsically safe systems (explosion-proof type "i").

This document applies to intrinsically safe systems that are intended to be used in whole

or in part in places where Class I, Class II or Class III Ex equipment is required.

Note 1: This document is used for the design and assessment of intrinsically safe systems; its

personnel may be the manufacturer, third-party organization, expert consultant or end-user staff.

This document supplements and modifies the general requirements of GB/T 3836.1 and

the intrinsic safety type of GB/T 3836.4. When the requirements of this document

conflict with the requirements of GB/T 3836.1 or GB/T 3836.4, the requirements of this

document take precedence.

The installation requirements of Class II or Class III intrinsically safe systems, which

are designed in accordance with this document, are specified in GB/T 3836.15.

Note 2: GB/T 3836.15 currently does not specify the installation requirements for Class I; the

installation requirements for Class I are under consideration.

2 Normative references

The contents of the following documents constitute essential clauses of this document

through normative references in the text. Among them, for dated references, only the

version corresponding to that date applies to this document; for undated references, the

latest version (including all amendments) applies to this document.

GB/T 3836.1 Explosive atmospheres - Part 1: Equipment - General requirements

(GB/T 3836.1-2021, IEC 60079-0:2017, MOD)

GB/T 3836.4 Explosive atmospheres - Part 4: Equipment protection by intrinsic

safety "i" (GB/T 3836.4-2021, IEC 60079-11:2011, MOD)

GB/T 3836.15 Explosive atmospheres - Part 15: Electrical installations design,

selection and erection (GB/T 3836.15-2017, IEC 60079-14:2007, MOD)

GB/T 16657.2 Industrial communication networks - Fieldbus specifications - Part 2:

connection to the combined power source:

- Maximum external capacitance Co; and

- Maximum external inductance Lo; or

- Maximum inductance to resistance ratio L/R of the connecting cable.

Any test-based verification shall be performed using a spark test device in accordance

with GB/T 3836.4, taking into account the safety factor of the combined device.

The Ui, Ii, Pi of each device in the system shall be greater than or equal to the Uo, Io, Po

determined above, respectively.

Note 2: Appendix E illustrates the analysis used in the most common combination of linear

resistor-limited output power sources. Alternatively, GB/T 3836.15 provides a simplified

analysis for Class II circuits with protection level "ib" where the power source is an associated

device. The analysis may also include a spark ignition test in accordance with GB/T 3836.4.