When selecting equipment for hazardous areas, markings such as Zone 1 or Zone 2 as well T4 or T6 are more than technical designations. They help determine whether equipment is suitable for the environment in which it will operate.
📌 𝗪𝗵𝗮𝘁 𝗱𝗼𝗲𝘀 𝘁𝗵𝗲 𝘇𝗼𝗻𝗲 𝘁𝗲𝗹𝗹 𝘂𝘀?
For flammable gas and vapor environments:
✅ 𝗭𝗼𝗻𝗲 𝟬: An explosive atmosphere is continuously present, exists for extended periods, or occurs frequently, typically for more than 1,000 hours per year.
✅ 𝗭𝗼𝗻𝗲 𝟭: An explosive atmosphere is likely to occur occasionally under normal operating conditions, typically for more than 10 but less than 1,000 hours per year.
✅ 𝗭𝗼𝗻𝗲 𝟮: An explosive atmosphere is not expected during normal operation but may occur briefly if conditions arise, typically for less than 10 hours per year. However, it is still sufficiently likely to require controls over potential ignition sources.
📌 𝗪𝗵𝗮𝘁 𝗱𝗼𝗲𝘀 𝘁𝗵𝗲 𝗧𝗲𝗺𝗽𝗲𝗿𝗮𝘁𝘂𝗿𝗲 𝗖𝗹𝗮𝘀𝘀 𝘁𝗲𝗹𝗹 𝘂𝘀?
The T-classification relates to the maximum surface temperature that equipment can reach:
✅ T1: 450°C
✅ T2: 300°C
✅ T3: 200°C
✅ T4: 135°C
✅ T5: 100°C
✅ T6: 85°C
💡 𝗧𝗵𝗲 𝗵𝗶𝗴𝗵𝗲𝗿 𝘁𝗵𝗲 𝘁𝗲𝗺𝗽𝗲𝗿𝗮𝘁𝘂𝗿𝗲 𝗰𝗹𝗮𝘀𝘀 (𝗧-𝗰𝗹𝗮𝘀𝘀), 𝘁𝗵𝗲 𝗹𝗼𝘄𝗲𝗿 𝘁𝗵𝗲 𝗰𝗼𝗿𝗿𝗲𝘀𝗽𝗼𝗻𝗱𝗶𝗻𝗴 𝗺𝗮𝘅𝗶𝗺𝘂𝗺 𝗽𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗯𝗹𝗲 𝘀𝘂𝗿𝗳𝗮𝗰𝗲 𝘁𝗲𝗺𝗽𝗲𝗿𝗮𝘁𝘂𝗿𝗲.
This distinction is important: the zone identifies the likelihood and duration of an explosive atmosphere, while the temperature class addresses the equipment’s surface-temperature limitation.
Both factors need to be considered alongside other requirements such as gas group, protection concept, equipment protection level, and the specific conditions of the installation.
At SESCO Industry, we understand that selecting equipment for hazardous environments requires more than matching a product to an application. It requires understanding the technical requirements of the installation.
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