What Does Ex tb IIIC T130°C Db Mean?
Time:2026-08-11
Dust Explosion Protection Marking: Ex tb IIIC T130°C Db
The explosion protection marking Ex tb IIIC T130°C Db indicates that the electrical equipment is designed and certified for use in hazardous areas where combustible dust may be present.
What Does Ex tb IIIC T130°C Db Mean?
Ex — Explosion Protection
Ex indicates that the electrical equipment complies with one or more explosion protection types specified in the EN/IEC 60079 series of standards and is designed for use in potentially explosive atmospheres.
tb — Protection by Enclosure for Combustible Dust
tb refers to the explosion protection type “Protection by Enclosure for Combustible Dust.”
According to theEN/IEC 60079 series, commonly used protection concepts for equipment intended for combustible dust environments include:
t — Protection by enclosure
i — Intrinsic safety
p — Pressurization
m — Encapsulation
The t type protection method prevents combustible dust from entering the equipment or reaching potential ignition sources, thereby reducing the risk of dust ignition under specified operating conditions.
Classification of Combustible Dust Hazardous Areas
Based on the frequency and duration with which combustible dust is present, hazardous areas are classified into three zones:
Zone 20
Zone 21
Zone 22
Zone 20
An area in which a cloud of combustible dust in air is present continuously, for long periods, or frequently during normal operation, and in which the quantity of dust is sufficient to form an explosive dust-air mixture.
Zone 20 may also include areas where combustible dust deposits or accumulations are present in such quantities that they may form an explosive dust-air mixture.
Zone 21
An area in which a cloud of combustible dust in air is likely to occur occasionally during normal operation in quantities sufficient to form an explosive dust-air mixture, but which is not classified as Zone 20.
Zone 22
An area in which a cloud of combustible dust in air is not likely to occur during normal operation, but if it does occur, it will exist only for a short period.
Zone 22 may also include areas where combustible dust may occasionally accumulate or form dust layers that could potentially generate an explosive dust-air mixture under abnormal conditions.
Summary
The marking Ex tb IIIC T130°C Db identifies equipment designed for combustible dust hazardous environments and provides information about its explosion protection method, dust group, maximum surface temperature, and equipment protection level.
Understanding the hazardous-area classification and explosion protection marking is essential when selecting electrical equipment for applications involving combustible dust, such as chemical processing, food processing, pharmaceuticals, grain handling, woodworking, and other industrial environments where dust explosion hazards may exist.
Dust Explosion Protection Marking: Ex tb IIIC T130°C Db
The explosion protection marking Ex tb IIIC T130°C Db indicates that the electrical equipment is designed and certified for use in hazardous areas where combustible dust may be present.
What Does Ex tb IIIC T130°C Db Mean?
Ex — Explosion Protection
Ex indicates that the electrical equipment complies with one or more explosion protection types specified in the EN/IEC 60079 series of standards and is designed for use in potentially explosive atmospheres.
tb — Protection by Enclosure for Combustible Dust
tb refers to the explosion protection type “Protection by Enclosure for Combustible Dust.”
According to theEN/IEC 60079 series, commonly used protection concepts for equipment intended for combustible dust environments include:
t — Protection by enclosure
i — Intrinsic safety
p — Pressurization
m — Encapsulation
The t type protection method prevents combustible dust from entering the equipment or reaching potential ignition sources, thereby reducing the risk of dust ignition under specified operating conditions.
Classification of Combustible Dust Hazardous Areas
Based on the frequency and duration with which combustible dust is present, hazardous areas are classified into three zones:
Zone 20
Zone 21
Zone 22
Zone 20
An area in which a cloud of combustible dust in air is present continuously, for long periods, or frequently during normal operation, and in which the quantity of dust is sufficient to form an explosive dust-air mixture.
Zone 20 may also include areas where combustible dust deposits or accumulations are present in such quantities that they may form an explosive dust-air mixture.
Zone 21
An area in which a cloud of combustible dust in air is likely to occur occasionally during normal operation in quantities sufficient to form an explosive dust-air mixture, but which is not classified as Zone 20.
Zone 22
An area in which a cloud of combustible dust in air is not likely to occur during normal operation, but if it does occur, it will exist only for a short period.
Zone 22 may also include areas where combustible dust may occasionally accumulate or form dust layers that could potentially generate an explosive dust-air mixture under abnormal conditions.
Summary
The marking Ex tb IIIC T130°C Db identifies equipment designed for combustible dust hazardous environments and provides information about its explosion protection method, dust group, maximum surface temperature, and equipment protection level.
Understanding the hazardous-area classification and explosion protection marking is essential when selecting electrical equipment for applications involving combustible dust, such as chemical processing, food processing, pharmaceuticals, grain handling, woodworking, and other industrial environments where dust explosion hazards may exist.
