The core difference between gas environment explosion-proof FFU and dust environment explosion-proof FFU lies in the completely different explosion-proof standards, sealing protection, temperature control, structural design and certification marks. The two cannot be interchanged. The following is a comparison from key dimensions:
1. Applicable environment and explosion mechanism
Gas explosion-proof FFU (Ex d)
Applicable: Lithium batteries (electrolyte vapor), pharmaceuticals (ethanol / acetone), chemical industries, etc. environments with flammable gases / vapors.
Mechanism: Gas molecules are uniformly mixed, encountering sparks / high temperatures causes instantaneous explosion, and the flame spreads quickly.
Dust explosion-proof FFU (Ex tD)
Applicable: Aluminum powder, carbon powder, milk powder, cocoa powder, etc. environments with combustible dust.
Mechanism: Dust suspends as a “dust cloud” or accumulates, encountering high temperature / sparks ignites, and prone to secondary explosion.
2. Explosion-proof standards and identification (the most distinguishable aspect)

III. Structural Design Differences (Core Hardware Differences)
1. Shell and Sealing
Gas Explosion-proof: Flameproof type (Ex d), thick shell that can withstand internal explosion pressure; precise gap at the joint (prevents flame from escaping); protection class IP54/IP55.
Dust Explosion-proof: Dust-tight type (Ex tD), fully sealed + no dead corners (prevents dust from entering and accumulating inside); protection class IP65/IP66 (higher, prevents dust intrusion); rounded shell design (no dust accumulation dead spots).
2. Motor and Electrical
Gas Explosion-proof Motor: Flameproof motor, sparks enclosed within the casing; ordinary insulation is sufficient.
Dust Explosion-proof Motor: Dust-proof + moisture-proof + anti-static design; full sealing of stator/rotor; anti-static coating (prevents static sparks); lower surface temperature (prevents dust layer from smoldering).
3. Filter and Anti-static
Gas FFU: Anti-static filter material is sufficient, no special sealing requirements.
Dust FFU: Anti-static + explosion-proof sealing strip (prevents dust penetration + static sparks); more compact filter material (prevents dust leakage).
IV. Temperature Control Logic (Safety-Critical)
Gas Explosion-proof: Control surface temperature < gas ignition temperature (e.g., T4 ≤ 135℃, suitable for ethanol/acetone).
Dust Explosion-proof: Control surface temperature < dust layer ignition temperature (usually 2/3 of gas ignition temperature);Gas FFU: CNEX/PCEC explosion-proof qualification Certificate (GB 3836);
V. Certification and Acceptance Requirements
Gas FFU： CNEX/PCEC explosion-proof certificate (GB 3836)； focus on flameproof gap + temperature group.
Dust FFU： CNEX/PCEC dust explosion-proof certificate (GB 12476)； focus on sealing grade + surface temperature + anti-static.
VI. Price Differences
Gas Explosion-proof FFU： Basic model 4000–6000 yuan / unit (Ex d IIB T4 + 304 + AC).
Dust Explosion-proof FFU： Configuration is 20%–40% more expensive than gas model (due to higher costs of sealing， anti-static， and temperature control).
VII. Common Selection Mistakes (Avoiding Pitfalls)
Gas FFU replacing Dust： Dust entering and accumulating inside → overheating and self-ignition → explosion risk； acceptance directly fails.
Only looking at temperature group： IP65 + full sealing for dust environment is a hard requirement， T6 cannot replace sealing.
Modifying a regular FFU to explosion-proof: Privately replacing the motor without an overall explosion-proof certification is a violation and poses a significant safety hazard.
Summary: Quick Selection comparison table
Lithium battery/pharmaceutical (ethanol) → Gas explosion-proof Ex d IIB T4
Hydrogen workshop → Gas explosion-proof Ex d IIC T6
Aluminum powder/carbon powder/milk powder → Dust explosion-proof Ex tD A21 IP65 T4