New version of GB/T3836 series standards has been officially implemented on May 1, 2022. The difference between the old and new standards is a concern for many corporate customers. The explosion-proof mark, as the "ID card" of the product, can allow users and installers to quickly understand the explosion-proof type, corresponding gas/dust, and temperature group of this explosion-proof product. In order to avoid the installation of gas explosion-proof products in dusty areas, and the installation of "n" type products in the explosion-proof area of Zone 1. Ensure that explosion-proof products are compatible with hazardous areas in terms of selection.

Based on the introduction in the new version of GB/T 3836-2021 standard, Zhongnuo Testing summarizes the content and significance of the explosion-proof mark for Ex equipment used in explosive gas environments. In the future, we will continue to share knowledge on explosion-proof signs for using Ex equipment in places with combustible dust.

The explosion-proof marking for Ex equipment used in explosive gas environments should include:

1、 The symbol Ex indicates that the Ex equipment complies with one or more explosion-proof types listed in Chapter 1 of GB/T 3836.1-2021.

2、 The explosion-proof protection type refers to the explosion-proof protection measures taken by the equipment. The explosion-proof protection type and corresponding code relationship are shown in the table below.

Note: In addition to the 8 explosion-proof protection types listed above, Ex equipment can also be used in explosive gas environments with radiation explosion-proof and special explosion-proof types. Due to the scarcity of such products, we will not elaborate further here.

3、 Explosive gas category

1. Class I: Coal mine gas

2. Class IIA, IIB, and IIC: Explosive gases other than coal mine gas environments, as shown in the table below.

Three types of explosive gas classification - watermarked - updated. jpg

4、 Temperature group refers to the temperature limit at which an explosive gas mixture can be ignited.

Electrical equipment is divided into groups T1-T6 according to its highest surface temperature, so that the highest surface temperature of the corresponding electrical equipment in groups T1-T6 cannot exceed the allowable value of the corresponding temperature group. The relationship between temperature group, equipment surface temperature, and ignition temperature of explosive gases or vapors is shown in the following table.

remarks:

1. The explosion-proof mark of Class I Ex equipment does not need to indicate the temperature group.

2. Under the same conditions, T6 equipment can be used in locations T1 to T5, T5 equipment can be used in locations T1 to T4, and so on.

3. For Class II Ex devices with a maximum surface temperature exceeding 450 ° C, Celsius temperature should be used to mark the maximum surface temperature, for example, 600 ° C.

4. Class II Ex equipment used for special gases does not need to indicate the corresponding temperature group or maximum surface temperature.

5. Ex components do not need to be labeled with temperature groups or maximum surface temperature (Celsius temperature).

5、 Applicable Equipment Protection Level (EPL)

The relationship between different equipment protection levels and explosion-proof areas is shown in the table below.

Remarks:

1. Ma/Mb is the protection level of Ex equipment for coal mine gas environment; Ga/Gb/Gc is an Ex equipment protection level for explosive gas environments other than coal mine gas environments

2. Under the same conditions, Ga>Gb>Gc, Ma>Mb

3. The EPL marked on Ex equipment may have stricter restrictions than the EPL typically used for specific explosion-proof types, to indicate other aspects of the equipment, such as material limitations. For example, when the aluminum content of the equipment exceeds the allowable value in GB/T 3836.1.8.3, the EPL level of the Ex equipment of ia is Gb, such as Ex ia II C T4 Gb.

The Ex logo should be marked in the order given in the above columns, with small intervals between them.

Example of Explosion proof Signs:

Ex ib I Mb

Ex: Electrical equipment marking for explosion-proof gas environments

IB: The protection type is intrinsic safety type

I: Coal mine gas environment

Mb: Device protection level, can be used in Zone 1

Ex db eb II C T6 Gb
Ex: Electrical equipment marking for explosion-proof gas environments
db: The protection type is explosion-proof
eb: The protection type is increased safety type

IIC: IIC Gas and Vapor Environment

T6: The temperature level is T6, and the maximum surface temperature of the equipment does not exceed 85 ° C

Gb: Device protection level, can be used in Zone 1/Zone 2