Ⅰ.Dust Explosion-Proof Certificate

A dust explosion-proof certificate is a legal document proving equipment can operate safely in explosive dust atmospheres. It falls under Group III explosion-proof certification and is only issued upon passing relevant type tests, serving as a "passport" for equipment to be used in hazardous locations.

It differs from Group I certificates for underground coal mines and Group II certificates for petrochemical gas environments. The three types of certificates are not interchangeable; selection must match on-site hazardous substances.

Ⅱ.Applicable Environments

Designed exclusively for non-mining explosive dust areas, including flour mills, coal powder plants, spray booths, polishing workshops, feed mills, food processing factories and other sites with combustible dust.

Ⅲ.Applicable Standards

GB/T 3836 series standards (e.g., GB/T 3836.31 Dust Ignition Protected Enclosure). The former GB 12476 series has been superseded.

Ⅳ.Common Explosion-Proof Types

● Intrinsically safe "i"

● Pressurized "p"

● Encapsulated "m"

● Dust ignition protected enclosure "t"

Ⅴ.Hazardous Zones Classification

Zone 20: Highest risk. Persistent or frequent dust clouds form during normal operation, such as inside dust silos, mixers and pulverizers.

Zone 21: Medium risk. Dust clouds may occasionally occur under normal operation, such as areas adjacent to dust vessels and zones liable to disturbed dust layers.

Zone 22: Low risk. Dust clouds only appear briefly and occasionally under abnormal conditions, such as rarely opened compartments and joints of pneumatic equipment.