Gas explosion-proof mark Ex d ib Ⅱ C T4 Gb
◆ Ex：Indicating that the electrical equipment complies with one or more explosion-proof types listed in the Chinese GB3836 series explosion-proof standards and can be used in explosive hazardous areas.
◆ d：The protection type is explosion-proof
◆ ib：The protection type is intrinsic safety type
Note: This explosion-proof mark includes two explosion-proof types, which belong to the composite type;
The GB3836 series explosion-proof standards specify the following gas explosion-proof types:
d： Explosion proof type
e： Increased safety type
i： Intrinsic safety type
p： Positive pressure type
o： Liquid immersion type
n: N-type
q： Sand filling mold
m： exm
◆ ⅡC：Electrical equipment used in explosive gas environments other than Class I coal mines that are prone to gas generation, commonly known as explosion-proof electrical equipment for factories. Class II electrical equipment is classified into three categories based on the minimum ignition spark energy of explosive gases: A, B, and C.
IIA: The representative gas is propane
IIB: Representative gas is ethylene
IIC: The representative gas is hydrogen gas
The IIC level is the highest and can be used for the use of IIB and IIA devices; IIB can be used for the usage conditions of IIA equipment.
If the electrical equipment is only used in a specific gas, write the chemical name or molecular formula of the gas in parentheses after symbol II, for example: "IIC (H2)";
If electrical equipment is used for a specific gas in addition to special electrical equipment categories, the chemical formula should be added after the category symbol and separated by the symbol "", for example: "IIB H2"
◆ T4：Temperature group, indicating that the maximum surface temperature of the equipment does not exceed T4, which is 135 ° C.
The GB3836 series explosion-proof standard specifies six temperature groups, namely:
The lower the maximum temperature of the device, the less likely it is to cause explosions in the surrounding environment and the better its safety performance. T6 equipment can be used for the usage conditions of T5, T4, T3, T2, T1, and so on.
◆ Gb：Protection level of equipment
The equipment used in explosive gas environments has a "very high" level of protection. During normal operation, expected or rare faults that occur are not ignition sources
※ Gb explosive gas environment equipment has a "high" protection level. Not the ignition source under normal operation or expected fault conditions
Equipment for explosive gas environments in Gc has a "general" protection level. In normal operation, if it is not the ignition source, additional protective measures can be taken to ensure that effective ignition will not occur in situations where the ignition source is expected to frequently occur (such as lamp failures)
In general:
Ga protection level devices can be used for Zone 0, Zone 1, and Zone 2
Gb protection level can be used for Zone 1 and Zone 2
Equipment with Gc protection level can use Zone 2
China divides explosive gas hazardous areas into three zones: Zone 0, Zone 1, and Zone 2
Zone 0: A place where explosive gas mixtures exist continuously or for a long period of time under normal circumstances.
Zone 1: Places where explosive gas mixtures may occur under normal circumstances.
Zone 2: Under normal circumstances, explosive gas mixtures are unlikely to occur, or even if they do, they will only exist for a short period of time.
Dust explosion-proof mark
Ex tD A21 IP65 T225°C T500320°C
◆ Ex：Indicating that the electrical equipment complies with one or more explosion-proof types listed in the Chinese GB3836 series explosion-proof standards and can be used in explosive hazardous areas.
◆ tD：The protection type is shell protection type,
The GB12476 series dust explosion-proof standards stipulate the following types of dust explosion-proof:
tD： Shell protection type
iD： Intrinsic safety type
pD： Positive pressure type
mD： exm
◆ A21：Class A electrical equipment used in Zone 21 of explosive dust environments
According to the frequency and duration of combustible dust environments, hazardous areas are divided into three zones. They are: Zone 20, Zone 21, and Zone 22.
※ Zone 20: Combustible dust continuously or frequently occurs during normal operation, and its quantity is sufficient to form a mixture of combustible dust and air and/or may form uncontrollable and extremely thick places and container interiors.
※ Zone 21: During normal operation, there may be a sufficient amount of dust to form a combustible mixture of dust and air, but it is not classified as Zone 20.
※ Zone 22: Places where combustible dust clouds occasionally appear and only exist for a short period of time under abnormal conditions, or where combustible dust occasionally accumulates or there may be a dust layer that produces combustible dust air mixtures.
◆ IP65：Shell protection level
◆ T225°CT500320 ° C: maximum surface temperature; If temperature tests are conducted at a certain dust layer thickness, the corresponding thickness values should also be marked separately.
The remaining rules are the same as those for equipment used in gas environments.
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