In the context of a flow meter, “E Ex iaⅡC T4” refers to the device’s classification according to international standards for electrical equipment used in explosive atmospheres. Here’s a breakdown of each part:
E Ex: This indicates that the equipment is designed and certified for use in explosive atmospheres, following the European ATEX (Atmosphères Explosibles) directive.
ia: This refers to the intrinsic safety level of the device. “ia” is the highest level of intrinsic safety protection, meaning that the device is designed to be safe even in the presence of two independent faults.
ⅡC: This defines the gas group classification. “ⅡC” is the most stringent gas group and includes the most dangerous gases, such as hydrogen and acetylene.
T4: This indicates the temperature class of the equipment. “T4” means that the surface temperature of the device will not exceed 135°C under fault conditions, making it safe to use in environments where explosive gases could ignite at lower temperatures.
So, in summary, “E Ex iaⅡC T4” means that the flow meter is certified for use in explosive atmospheres, is intrinsically safe even under two fault conditions, is suitable for the most hazardous gases, and will not exceed a surface temperature of 135°C.
In the context of hazardous area classifications, the temperature classes T1 to T6 represent the maximum surface temperature that equipment can reach under fault conditions. These classes help determine the suitability of equipment for use in environments with different types of explosive gases or vapors. Here’s what each temperature class means:
- T1: Maximum surface temperature of 450°C
- T2: Maximum surface temperature of 300°C
- T3: Maximum surface temperature of 200°C
- T4: Maximum surface temperature of 135°C
- T5: Maximum surface temperature of 100°C
- T6: Maximum surface temperature of 85°C
The lower the T-class number, the higher the maximum surface temperature allowed. Equipment with a T6 rating, for example, is the safest in terms of temperature, as it will not exceed 85°C, making it suitable for environments with very low ignition temperature gases.
