What is the difference between Ex dII BT4 and Ex dII CT4?
 
 In hazardous environments, it is essential to have specially designed explosion-proof equipment. This is where Ex-rated certification comes into play. Two common approvals are Ex dII BT4 and Ex dII CT4. While both certifications are designed for security, there are key differences between the two.
 
 Ex dII BT4 certification stands for "Explosion-proof, dust-ignition-proof and temperature class T4". This certification applies to equipment used in hazardous areas where combustible dust is present. These areas are commonly found in industries such as pharmaceuticals, food processing and grain handling.  The T4 rating means that the device can withstand a surface temperature of up to 135 degrees Celsius.
 
 Ex dII CT4 certification, on the other hand, stands for "Explosion-proof, dust-ignition-proof and temperature class T4". This certification applies to equipment used in hazardous areas where flammable gases or vapors are present. These areas are commonly found in industries such as oil and gas, chemical manufacturing, and mining. The temperature class T4 rating means that the device can withstand a surface temperature of up to 135 degrees Celsius, similar to Ex dII BT4 certification.
 
 The main difference between Ex dII BT4 and Ex dII CT4 is the type of hazardous elements they protect against.  Ex dII BT4 certification is designed for equipment protected against explosions caused by combustible dusts, while Ex dII CT4 certification is designed for equipment protected against explosions caused by combustible gases or vapours. Therefore, the choice of certification depends on the presence of specific hazardous elements in the environment in which the equipment is used.
 
 It's worth noting that both certifications require the device to be enclosed in a rugged enclosure to withstand the pressure and contain any explosion that might occur. The enclosure has been carefully designed and tested to ensure protection against ignition of surrounding hazardous materials.
 
 In summary, the difference between the Ex dII BT4 and Ex dII CT4 certifications is the type of hazardous elements they protect against.  Ex dII BT4 is designed for use in equipment with combustible dust areas and Ex dII CT4 is designed for use in areas with flammable gases or vapours. By understanding these differences, industries can select the appropriate explosion protection equipment for their specific hazardous environments, keeping employees safe and preventing potentially catastrophic events.