Discussion on the explosion protection rating of explosion-proof motors for use in hydrogen environments
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Dear colleagues: In the past, the explosion-proof rating for motors used in hydrogen environments was DIICT4. May I ask if it is acceptable to use motors with an explosion-proof rating of “DIIBT4 + hydrogen” in such environments?
No, it must be of Class C. For details, please refer to the installation specifications for electrical equipment in explosive environments
Devices marked IIB can meet the requirements applicable to IIA devices, while devices marked IIC can meet the requirements of both IIA and IIB devices. Therefore, it is not permissible to use equipment with an explosion protection rating of DIIBT4 in a hydrogen environment, as this does not satisfy the required explosion protection standards.
This post was last edited by chb1534 on May 14, 2018, at 14:26. Products labeled “dIIBT4+H2” can be used, as such products are essentially equivalent to “dIICT4” products, except in environments containing acetylene. In other words, they can be utilized in any “dIICT4” environment where acetylene is not present. Of course, some people understand that dIIBT4 and a hydrogen environment are usable, but in either case, a hydrogen environment is available.
For hydrogen, I remember it works for CT2 and above; BT4 definitely doesn’t work
The hydrogen explosion hazard category is IICT1; the IIB series does not meet the requirements.
The NE505 standard in the United States classifies gas categories into GROUP A (representing the gas “acetylene”), GROUP B (representing the gas “hydrogen”), GROUP C (representing the gas “ethylene”), and GROUP D (representing the gas “methane”). GROUP A has the highest classification level； Our **GB3836 gas classification divides gases into three categories: IIA, IIB, and IIC. Among these, the IIC category includes acetylene, hydrogen, and carbon disulfide. In reality, our IIC category corresponds to the highest standard, i.e., GROUP A under NE505. However, using IIC products for applications designated as GROUP B actually constitutes an over-specification, meaning that higher-grade products are being used where lower-grade ones would suffice.** Additionally, the GB3836 standard stipulates that in acetylene environments, flat flameproof surfaces must not be used. Therefore, most commonly seen products with an IIC explosion-proof rating feature “spigot-type” flameproof surfaces. In reality, however, hydrogen is more frequently used in IIC environments. Some manufacturers, in order to reduce the cost of their products for use in hydrogen environments, design them using flat flameproof surfaces while ensuring that all other parameters comply with IIC requirements. Such products can indeed be used in hydrogen environments, but not in acetylene environments. Consequently, they cannot be issued an IIC certificate; instead, only an IIB+H2 certificate can be granted. This is precisely the problem mentioned by the original poster.
According to the specifications, CT4 does not meet the requirements; CT1 is necessary, with a higher temperature category!
The explosion protection rating of the selected electrical equipment is clearly indicated as: Ex dIICT4 Gb
See the link “https://bbs.hcbbs.com/thread-1680350-1-1.html”
The new GB3836.15-2017 standard has been released. For information on this explosion-proof marking, refer to Clause 10.1 of GB3836.15-2017; the dIIBT4+H2 explosion-proof marking permits use in hydrogen environments.