Intrinsic Safety (“i”) Explosion-Proof Certification is a certification system for electrical equipment used in hazardous environments. It prevents sparks or high temperatures sufficient to ignite explosive mixtures by limiting energy (electrical and thermal energy). Its core essentials and applicable standards are outlined below:

I. Core Essentials

1. Principle of Intrinsic Safety

The core principle is to limit the energy of electrical equipment through design, ensuring that the sparks and thermal effects generated by the equipment under normal operation or fault conditions cannot ignite the surrounding explosive mixtures (gases, vapors, dust, etc.).

2. Equipment Classification

ia Grade: Ensures safety under normal operation and two fault conditions; applicable to Zones 0, 1, 2 and Zones 20, 21, 22.

ib Grade: Ensures safety under normal operation and one fault condition; applicable to Zones 1, 2 and Zones 21, 22.

ic Grade: Ensures safety under normal operation only; applicable to Zones 2 and 22.

3. Requirements for Associated Equipment

Intrinsic safety equipment is typically used in conjunction with safety barriers (associated equipment). Installed between hazardous and non-hazardous areas, safety barriers limit the energy flowing into hazardous areas and prevent high energy from non-hazardous areas from conducting into hazardous zones.

4. Circuit Design Requirements

Adopt low-power components and limit capacitance and inductance in circuits to excessive energy storage.

The cross-sectional area and insulation grade of wires must comply with regulations to prevent short circuits or electric leakage.

Circuits must pass spark tests and hot surface tests to verify their safety.

II. Applicable Standards

1. National Standards (GB)

GB/T 3836.1-2021: Explosive atmospheres – Part 1: General requirements for equipment

GB/T 3836.4-2021: Explosive atmospheres – Part 4: Intrinsic safety "i"

2. International Standards (IEC)

IEC 60079-0: Explosive atmospheres – Part 0: General requirements for equipment

IEC 60079-11: Explosive atmospheres – Part 11: Intrinsic safety "i"

3. European Standards (EN)

EN 60079-0: Explosive atmospheres – Part 0: General requirements for equipment

EN 60079-11: Explosive atmospheres – Part 11: Intrinsic safety "i"

4. Standards for Other Regions

United States: UL 913 (Standard for Intrinsic Safety Equipment)

Canada: CSA C22.2 No. 157 (Intrinsic Safety Equipment)

Intrinsic safety explosion-proof certification applies to low-power equipment such as communication devices, sensors, instruments, and small control devices. It is widely used in explosive environment industries including petroleum, chemical engineering, coal mining, and pharmaceuticals.

Certification must be conducted by qualified explosion-proof inspection institutions (e.g., National Quality Supervision and Inspection Center for Explosion-Proof Electrical Products) to ensure the equipment meets safety requirements.

As a third-party institution long focused on the field of explosion-proof certification, STS employs dedicated engineers for intrinsic safety circuit and structural design. We provide technical consulting services including explosion-proof circuit design, drawing drafting, and rectification, with rich experience in the design and certification of ia, ib, and ic intrinsic safety explosion-proof grades. If you have certification needs in this regard, feel free to contact us via private message!