1、 Standard positioning
The laser uses GB/T 3836.22, which is essentially a "light radiation ignition explosion-proof" standard: it determines whether the laser/light radiation will become an ignition source in explosive gas or dust environments, rather than the occupational safety of the laser on human eyes and skin. The current version is GB/T 3836.22-2023, published on December 28, 2023, implemented on July 1, 2024, replacing GB/T 3836.22-2017, and modified to adopt IEC 60079-28:2015.
2、 Scope of application
Suitable for optical radiation devices with wavelengths ranging from 380 nm to 10 μ m, including lasers LED、 Lighting fixtures, optical fibers, and optical transmission systems; This includes both equipment installed in explosive environments and equipment installed outside hazardous areas where the beam of light enters the explosive environment. Covering Class I, II, and III equipment, EPL includes Ga, Gb, Gc, Da, Db, Dc, Ma, Mb.
3、 Ignition mechanism
The standard captures two types of ignition paths: one is that the surface or particles absorb light and heat up, reaching a temperature that can ignite the surrounding explosive environment; The second is the rare but high-risk strong light beam focusing, where the laser directly penetrates the gas near the focal point, generating plasma and shock waves, and nearby solid materials can exacerbate this process.
4、 Three types of protection
The standard provides three types of explosion-proof optical radiation: intrinsic safety optical radiation "op is", protective optical radiation "op pr", and optical system with interlocking device "op sh".
For lasers, op relies on limiting the continuous wave power, pulse peak/energy, irradiance, or energy density to a level that cannot ignite; OP PR uses optical fibers, windows, enclosed optical paths, or mechanical protection to confine hazardous radiation within controlled media; OP SH will quickly shut down or lower to a safe level through interlocking in the event of fiber breakage, loose joints, or shield opening failures, while also assessing the risk of residual/energy storage release after shutdown.
5、 Key points of laser compliance
The key is not just to look at the "Ex" logo, but to clearly specify the type of optical radiation protection, equipment group, EPL/applicable area, and continuous wave/pulse working mode in the selection document and nameplate. In engineering, the worst-case scenario should be calculated: maximum output power, pulse width and repetition frequency, peak power, beam divergence angle, focusing ability, fiber coupling efficiency, and end face contamination/damage; Invisible infrared, high peak power Q/mode-locked lasers, and long-distance single-mode fiber coupling are usually higher risk points. The specific limit values cannot be applied to laser safety levels, and should be evaluated or checked according to GB/T 3836.22 for different EPLs, light source types, and test conditions.
6、 Testing and documentation
When the optical limit can be proven through evaluation or beam intensity measurement, the ignition type test can be exempted; When it cannot be proven, ignition tests, verification of the applicability of the test device, and result judgment shall be conducted according to the standards. The standard catalog also includes benchmark test data, typical fiber optic cable structures, ignition hazard assessment, ignition mechanism information, and pulse assessment process.
7、 Confusing points
Do not mix GB/T 3836.22 with GB 7247/IEC 60825 laser product safety: the former is aimed at the risk of ignition in explosive environments, while the latter is aimed at exposure to human eyes/skin. Actual products often need to consider both "explosion-proof ignition" and "laser personal safety" at the same time, but the final certification of explosion-proof qualification still needs to fall on the OP IS/OP PR/OP SH of GB/T 3836.22 and the GB/T 3836.1 marking rules.
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