Gushine Lithium Battery Explosion Protection Guide | Understanding Ex Markings

Gushine Electronics

From petrochemical facilities and underground mining sites to offshore platforms and hazardous material storage, our explosion-protected lithium batteries deliver reliable power where safety matters most.

More than just batteries, they’re built with advanced designs and materials to remove ignition risks in explosive environments. This article explores three key areas: how explosion-proof batteries are applied across high-risk sectors, the classification of explosion-proof standards, and Gushine’s customized solutions that quietly protect lives and operations where safety matters most.

1.Key Applications of Explosion-Proof Lithium Batteries

With their specialized safety designs, explosion-proof lithium batteries play a vital role in industries where flammable or explosive risks are present. Here are some of the main areas where these batteries are widely used:

Application	Why Safety Matters	Standards / Technologies
Petrochemical facilities(refineries, gas stations, chemical plants)	Flammable gases mean even a minor spark or thermal event can lead to catastrophic ignition.	Explosion-proof battery packs, IECEx- and ATEX-certified, designed to prevent thermal runaway and ensure safe operations.
Mining and Underground Work (inspection gear, comms, rescue equipment)	Enclosed spaces and methane buildup demand the highest safety standards.	Intrinsically safe battery systems built to stay safe even under fault conditions, eliminating ignition risks.
Emergency Response & Firefighting (radios, phones, rescue robots, emergency lights)	Rescue zones are unpredictable, often with gas leaks or chemical spills.	High-safety, high-energy packs with IP67/IP68 protection for reliable performance in extreme conditions.
Aerospace & Defense (airborne systems, portable military devices)	Extreme safety demands near fuel tanks, ammunition depots, or sealed cabins.	High-reliability, explosion-proof cells, tested and certified to multiple international safety standards.
Marine & Offshore(tankers, drilling platforms, vessels)	Flammable vapors, high humidity, and corrosion risks challenge equipment durability.	Explosion-proof and corrosion-resistant designs, with stainless housings and anti-vibration builds.

2.Explosion Protection Classification

Explosion-proof classification is not defined by a single parameter. Instead, it is determined by the combination of multiple factors, including the type of protection method, the gas group, and the temperature class. Together, these elements form the complete explosion-proof marking, as illustrated in the diagram below.

（Refer to points 1–4 below）

2.1 Flameproof type

Flameproof type	Symbol	Principle Overview	Typical Applications
Intrinsic Safety	Ex ia / ib	Limits energy (voltage and current) at the circuit level so that ignition of flammable gas mixtures cannot occur. Grade “ia” offers the highest safety level.	Portable devices: explosion-proof radios, handheld terminals, etc.
Flameproof Enclosure	Ex d	Encloses cells and circuits within a robust housing capable of withstanding internal explosions without igniting the external atmosphere.	High-power devices: explosion-proof robots, large backup power supplies, lighting fixtures.
Encapsulation	Ex ma / mb	Fully seals cells and critical circuits in epoxy resin or similar solid materials to prevent ignition.	Small modules: battery packs, sensor power supplies, BMS protection boards.
Protection by Construction	b	Implements protective measures as defined in GB 3836.35 to prevent internal or external ignition sources.	Batteries, battery systems, energy storage units.
Combination of Protection Methods	e.g. Ex d[mb]	Uses two or more protection Methods to provide layered safety. For example, ani flameproof housing (d) containing encapsulated (m) and construction-protected (b) components.	Hybrid applications requiring redundancy, such as mixed-technology enclosures.
Increased Safety	Ex e	Enhances design features (e.g., improved insulation, reduced temperature rise, reinforced connections) to ensure safe operation.	Junction boxes, motor housings, certain transformers.
Oil Immersion	Ex o	Immerses electrical parts in protective oil to prevent ignition of gases outside the enclosure.	Transformers, switches.
Powder Filling	Ex q	Fills enclosures with quartz sand or other specified powder materials to absorb arcs and limit surface temperature.	Capacitors, fuses, small electronic components.
Pressurization	Ex px / py / pz	Maintains a higher pressure inside the enclosure using protective gases (air or inert gases) to prevent entry of explosive atmospheres.	Large analyzers, control cabinets, industrial motors.
Non-Sparking (n-type)	Ex nA / nC / nL / nR / nZ	A method designed for Zone 2 equipment, ensuring no ignition under normal operating conditions.	Terminal blocks, luminaires, small motors for Zone 2 environments.

Note: Explosion protection combinations follow strict rules of standards, logic, and certification — never just a string of symbols.

2.2 Gas Groups (Applicable Environments)

Standard (China / IEC / EU)	North America (Group)	Typical Gas	Maximum Experimental Safe Gap (MESG, mm)	Minimum Ignition Current Ratio (MICR)	Ignition Characteristics
I	D	Methane	1.14	1.0	Difficult to ignite
IIA	D	Propane	0.9 < MESG < 1.14	0.8 < MICR < 1.0	Easier
IIB	C	Ethylene	0.5 < MESG < 0.9	0.45 < MICR < 0.8	Higher risk
IIC	B	Acetylene	MESG < 0.5	MICR < 0.45	Very high risk
IIC	A	Hydrogen	MESG < 0.5	MICR < 0.45	Extremely high risk

Note: The smaller the Maximum Experimental Safe Gap (MESG) and the lower the Minimum Ignition Current Ratio (MICR), the easier the gas can ignite — indicating a higher hazard level.

2.3 Temperature Classes (Maximum Surface Temperature of Equipment)

The surface temperature of electrical equipment during operation must remain below the ignition temperature of the surrounding gases. T1 allows the highest temperature (450 °C), while T6 is the most stringent (85 °C).

Temperature Class	I Gas (Methane)	IIA Gases	IIB Gases	IIC Gases
T1 (450 °C)	Methane	Ethane, Propane, Acetone, Styrene, Chlorobenzene, Toluene, Benzene, Ammonia, Carbon monoxide, Formaldehyde, Aniline	Coke oven gas, Cyclopropane, Acrylonitrile	Water gas, Hydrogen
T2 (300 °C)	–	Butane, Methanol, Ethanol, Propylene, Vinyl chloride, Butyl acetate, Amyl acetate	Ethylene oxide, 2-Epoxypropane, Ethylene, 1,3-Butadiene	Acetylene
T3 (200 °C)	–	Pentane, Hexane, Heptane, Decane, Octane, Gasoline, Chlorobutane	Dimethyl ether, Hydrogen sulfide, Tetrahydrofuran, Acrolein	–
T4 (135 °C)	–	Diethyl ether, Trimethylamine	Tetrafluoroethylene, Diethyl ether	–
T5 (100 °C)	–	–	–	Carbon disulfide
T6 (85 °C)	–	Ethyl nitrite	–	Ethyl nitrate

Note: The temperature class indicates the maximum surface temperature the equipment can reach without igniting surrounding gases. Lower class numbers (T6) correspond to stricter safety requirements.

2.4 Equipment Protection Levels (EPL)

Zone	Description	Hazard Level	Required EPL
Zone 0	Areas where explosive gas atmospheres are present continuously or for long periods.	Extremely high	Ga (Very high protection level)
Zone 1	Areas where explosive gas atmospheres are likely to occur occasionally during normal operation.	High	Gb (High protection level)
Zone 2	Areas where explosive gas atmospheres are unlikely during normal operation, and if they occur, it will be only for a short time.	Medium	Gc (Enhanced protection level)

Note: The EPL (Equipment Protection Level) specifies the degree of protection required for electrical equipment in each hazardous zone.

2.5 Full Explosion Protection Code

Commonly used on top-tier explosion-proof batteries, motors, and related equipment.

3. Explosion Protection Certifications

Certification / Standard	Primary Applicability	Role / Relationship
GB 3836 (China National Standard)	Mainland China	Serves as the technical rule for certification. Products compliant with this standard can obtain the Chinese explosion-proof certificate displaying the corresponding marking.
IEC 60079 (International Standard)	Globally recognized	Acts as the international technical rule. Most global explosion protection standards (including GB 3836/IECEx) are based on it and form the technical basis for determining the explosion protection marking.
ATEX (EU Directive)	European Economic Area	Serves as the market “entry permit” for the EU. Products meeting ATEX requirements can bear the explosion-proof marking to enter the EU market.
IECEx (International Certification System)	IECEx member countries	Functions as an international “passport.” It certifies compliance with IEC standards and authoritatively records the explosion protection marking, accepted by multiple countries.

4. Gushine’s Custom Battery Solutions for Hazardous Environments

At Gushine, we know that every hazardous-location application — whether Ex ib IIC T4, Ex d I Mb, or other classifications — presents unique challenges, from extreme temperatures and high humidity to corrosive atmospheres and intense vibration.

Our expertise is built on three pillars:

• In-depth consultation We collaborate with your engineering teams to define intrinsic safety levels, available installation space, power and capacity requirements, environmental stress factors, and applicable certifications (GB3836, IEC60079-11-2023, ATEX, IECEx, etc.).
• Tailored design

Selecting the most suitable potting materials and optimized manufacturing processes.
Customizing BMS solutions, including safety algorithms, communication protocols, and hardware interfaces.
Designing battery modules that meet intrinsically safe or explosion-protected requirements for the intended environment.

• Certification support Supplying full technical documentation and providing engineering support to streamline system-level explosion safety certification.