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Explosion-Proof Ventilation Fans | Certified Hazardous-Area Air Movement | YONGFAN
Certified Hazardous-Area Protection · GB 3836 / IECEx Standards

Explosion-Proof Fans: Certified Safety Matched to Hazardous Gas Zones

Explosion-proof fan selection begins with the hazardous area classification — not airflow alone. A certified Ex motor is only one component; non-sparking impellers, casing clearances, earthing, and surface temperature limits complete the safety system.

Compare YONGFAN DFBZ / BDFBZ dedicated bifurcated fans, BT35-11 isolated-motor fans, BWEX-EX4 shallow wall units, and Ex-rated DTF tube axial fans across airflow (552 to 114,829 m³/h), pressure (32 to 2,266 Pa), Zone 1 / Zone 2 gas groups (IIA, IIB, IIC), and GB 3836 T4 temperature classes.

4 Ex ArchitecturesDFBZ · BT35 · BWEX · Ex-DTF
Airflow Spectrum552 – 114,829 m³/h
Pressure Range32 – 2,266 Pa ΔPt
Ex ClassificationGB 3836 / ExdbIIBT4 / ExdbIICT4
Compare Ex Fan Families Hazardous Area Checklist
YONGFAN smoke-exhaust axial fan
Hazardous Area Protection Zone 1 / Zone 2 Gas Groups · Non-Sparking Alloy Impellers · GB 3836 T4 Limits
01 / Hazardous Safety Protocol

Explosion-Proof Fan Failures Start with the Area Classification

A hazardous-area fan can deliver the exact design airflow and still be rejected on site if the gas group, temperature class, or certification scheme does not match the facility classification.

The first critical mistake is specifying only “explosion-proof” without providing the hazardous zone (Zone 1 or Zone 2), gas group (IIA, IIB, IIC), and temperature class (T1 to T6).

The second mistake is assuming an Ex motor makes the whole fan explosion-proof. The complete assembly — including non-sparking aluminium/brass blade rims, antistatic casing earthing, flameproof terminal boxes, and certified cable glands — must be certified as an integrated system.

The third mistake is confusing gas zones with combustible dust zones. An Ex d IIB T4 gas marking does not certify equipment for combustible dust unless explicit dust certification (e.g. Ex tb) is provided.

YONGFAN smoke-exhaust fan product set

Zone 1 & Zone 2 Classification

Zone 1 (flammable gas likely in normal operation) and Zone 2 (unlikely/infrequent) determine equipment protection levels under GB 3836 and IECEx.

GB 3836.1 / IEC 60079-0 · Gas Zones

Gas Groups: IIA · IIB · IIC

From propane (IIA) and ethylene (IIB) to hydrogen/acetylene (IIC), gas groups define ignition spark energy thresholds.

Gas Groups · Spark Energy Limits

Temperature Class (T1–T6)

Limits maximum fan surface temperature (e.g. T4 ≤ 135 °C) to prevent auto-ignition of ambient gases.

T4 Class ≤ 135 °C · Thermal Safety
02 / Equipment Breakdown

Four Explosion-Proof Ventilation Architectures for Hazardous Facilities

Detailed technical specifications and certification parameters across DFBZ, BT35-11, BWEX-EX4, and Ex-rated DTF fan families.
Route 01 · Dedicated Ex Bifurcated 552 – 58,343 m³/h · Zone 1 / Zone 2

DFBZ / BDFBZ Explosion-Proof Bifurcated Axial Fan

Dedicated explosion-proof bifurcated axial fan engineered specifically for chemical plants, battery charging rooms, oil refineries, and solvent handling zones under GB 3836 standards.

Performance covers 552 to 58,343 m³/h airflow and 32 to 420 Pa total pressure with 5 factory-set blade pitch angles (15° to 35°). Features a spark-free non-ferrous cast alloy impeller with the explosion-proof motor isolated inside an atmospheric bypass chamber away from the hazardous gas flow.

Non-Sparking AlloyCast aluminium-magnesium alloy wheel eliminates frictional sparks
Bifurcated IsolationMotor housed in isolated tunnel with clean external air cooling
Certified RatingGB 3836 ExdIIBT4 rating for Zone 1 and Zone 2 gas atmospheres
Blade Pitch Adjust5 factory blade angles for precise volume and motor kilowatt matching
Request DFBZ Sizing Compare vs BT35
YONGFAN smoke-exhaust axial fan
DFBZ / BDFBZ Series Dedicated Bifurcated Ex Fan · Non-Sparking Impeller · Motor Isolated
Route 02 · T35-Matched Ex Bifurcated Direct T35 Replacement · Ex Motor

BT35-11 Bifurcated Explosion-Proof Axial Fan

The explosion-proof counterpart to the standard T35-11 bifurcated fan. Shares identical duct mounting flanges, housing dimensions, and blade pitch settings (15° to 35°).

Covers 552 to 58,343 m³/h and 32 to 420 Pa total pressure. Upgraded with an Ex flameproof motor, non-sparking casing liners, and antistatic earth bonding. Perfect for upgrading existing T35 ventilation systems when area classifications change to hazardous.

T35 InterchangeabilityDirect 1:1 dimensional and flange match with standard T35-11
Ex Motor BuildGB 3836 flameproof motor mounted in bifurcated bypass chamber
Operating Range552 – 58,343 m³/h · 32 – 420 Pa total pressure
Airstream LimitContinuous operation up to 80 °C hazardous air exhaust
Request BT35 Sizing T35 vs BT35 Upgrade
YONGFAN smoke-exhaust fan product set
BT35-11 Series T35 Compatible Flanges · Ex Flameproof Drive · 80 °C Limit
Route 03 · Compact Wall Ex Fan ExdIIBT4 · Ø250 – Ø1000 mm

BWEX-EX4 External-Rotor Wall Fan

Engineered for shallow wall penetrations, paint spray storage rooms, gas cylinder bays, and solvent dispensing rooms where axial space does not permit long cylindrical tube fans.

Diameters span Ø250 to Ø1000 mm. Uses an integrated external-rotor explosion-proof motor hub with non-sparking aluminium blades. Complete with square wall mounting frame, safety wire guards, and certified flameproof terminal enclosure.

Shallow DepthExternal-rotor motor integrated inside impeller hub saves wall depth
Ex MarkingCertified ExdIIBT4 for Zone 1/2 solvent & chemical storage
Wall IntegrationSquare mounting flange with pre-drilled wall anchor points
Spark ProtectionPrecision machined aluminium blade tips and safety screen
Request BWEX Sizing Wall vs Tube Ex
YONGFAN square wall-mounted axial fan
BWEX-EX4 Series Ultra-Shallow Wall Mount · ExdIIBT4 Rated · Paint & Chemical Rooms
Route 04 · High-Pressure In-Duct Ex Up to 2,266 Pa · ExdbIIBT4 / ExdbIICT4

Ex-Rated DTF Axial-Flow Tube Fan

When ducted hazardous-area systems require higher airflow and total static pressure than bifurcated fans can develop, the Ex-rated DTF tube axial fan provides the required aerodynamic capability.

Published performance reaches 1,886 to 114,829 m³/h and 115 to 2,266 Pa total pressure with impellers up to Ø1600 mm. Built with heavy-gauge cylindrical casings, spark-resistant aluminium alloy wheels, and certified ExdbIIBT4 or ExdbIICT4 motors.

High Pressure HeadDevelops up to 2,266 Pa ΔPt for long ducted hazardous runs
IIC Gas OptionAvailable with certified ExdbIICT4 motors for hydrogen atmospheres
Impeller DiametersØ350 to Ø1600 mm with precision tip spark clearances
In-Line MountingDirect flange bolting in straight circular ductwork
Request Ex-DTF Sizing Review IIC Gas Data
YONGFAN smoke-exhaust axial fan
Ex-Rated DTF Series Up to 2,266 Pa Total Pressure · ExdbIIBT4 / ExdbIICT4 Options
03 / Selection Matrix

Explosion-Proof Fan Routing & Comparison Table

Cross-reference all four explosion-proof ventilation families by hazardous duty solved, aerodynamic boundary, and first confirmation input.
Product Family What It Solves Range Boundary from YONGFAN Data First Input to Confirm Action
DFBZ / BDFBZ Bifurcated Ex Fan
 Dedicated explosion-proof bifurcated ventilation; motor completely outside gas path
552 – 58,343 m³/h · 32 – 420 Pa ΔPt · GB 3836 T4
 Confirm Zone 1/2 gas group (IIB/IIC) and check that required pressure is ≤ 420 Pa Configure DFBZ
BT35-11 Bifurcated Axial Fan
 Direct Ex upgrade matching existing standard T35-11 dimensions and flanges
552 – 58,343 m³/h · 32 – 420 Pa ΔPt · Up to 80 °C
 Confirm direct replacement requirements for existing T35 duct connections Configure BT35
BWEX-EX4 External-Rotor Wall Fan
 Compact wall and duct-end ventilation in classified solvent & battery rooms
Ø250 – Ø1000 mm diameters · ExdIIBT4 marking
 Confirm wall opening aperture, mounting depth, and verify pressure drop is low Configure BWEX
Ex-Rated DTF Axial Tube Fan
 High airflow and higher static pressure in long ducted hazardous installations
1,886 – 114,829 m³/h · 115 – 2,266 Pa ΔPt · Ø350–Ø1600 mm
 Confirm motor sits in airstream; specify ExdbIIBT4 or ExdbIICT4 for gas group Configure Ex-DTF
04 / Procurement Protocol

13 Project Inputs Required Before Explosion-Proof Fan Sizing

Hazardous-area enquiries require the site classification document first. Airflow and pressure define the fan; classification defines the legal safety certification.
Hazardous Engineering Checklist

13 Mandatory Inputs for Ex Fan Quotation

Submitting these parameters prevents dangerous misapplication (such as using IIB fans in hydrogen IIC environments) and ensures full certification compliance.

1. Gas or Vapor Involved (Solvent, H2, Hydrocarbon)
2. Hazardous Area Zone (Zone 1 or Zone 2)
3. Required Gas Group (IIA, IIB, or IIC)
4. Permitted Temperature Class (T1 to T6)
5. Certification Scheme: GB 3836 / IECEx / ATEX
6. Ambient Site Temperature Range (°C)
7. Process-Air Stream Operating Temperature (°C)
8. Required Ventilation Airflow (m³/h / CFM)
9. Required Total Pressure (Pa ΔPt)
10. Gas Concentration & Moisture / Corrosive Risk
11. Mounting: In-Duct, Wall Aperture, Rooftop
12. Power Supply (220V / 380V / 50Hz / 60Hz)
05 / Quality Control

YONGFAN Explosion-Proof Manufacturing & Safety Controls

Strict production verification ensuring mechanical spark-free operation, electrical flameproof integrity, and certified submittal documentation.
Spark Prevention

Non-Sparking Blade Rims

Cast aluminium-magnesium alloy wheels with copper/brass casing rubbing strips eliminate mechanical friction sparks during potential impeller contact.

Ex Certification

Certified Flameproof Motors

Equipped exclusively with certified flameproof motors (GB 3836 Exd / Exdb) featuring machined flamepath joints and sealed terminal boxes.

Antistatic Bonding

100% Earth Continuity

Complete structural bonding across casing sections, motor frames, and terminal grounding lugs eliminates electrostatic charge buildup.

Traceability

Serialized Ex Certificates

Every unit is supplied with certified explosion-proof test reports, motor nameplate data, and dimensional submittal drawings.

Certified Submittal Package: GB 3836 explosion-proof certificates, motor type test reports, spark clearance inspection logs, and 3D BIM models supplied. Custom Built for Project Specs: Configured by gas group (IIB/IIC), temperature class (T4), and voltage requirements.
06 / Technical Q&A

Explosion-Proof Fans Frequently Asked Questions

Direct engineering answers covering gas groups, IIC options, DFBZ vs BT35, dust vs gas ratings, and fire duty.

Which YONGFAN Ex fan has the highest published pressure capability?

Ex-Rated DTF Series provides the highest pressure capability, reaching up to 2,266 Pa total pressure with airflow up to 114,829 m³/h.

Which fan should I use for Zone 1 or Zone 2 solvent vapors?

DFBZ / BDFBZ or BT35-11 are ideal for solvent vapors up to 420 Pa, isolating the motor from the airstream. For higher duct resistance, specify Ex-rated DTF.

Which YONGFAN fan has an IIC gas group option?

Ex-Rated DTF Series can be configured with certified ExdbIICT4 flameproof motors for hydrogen and acetylene hazardous atmospheres.

Which Ex fan is most compact for a wall opening?

BWEX-EX4 Series is specifically designed for wall mounting with an integrated external-rotor explosion-proof motor saving axial depth.

What is the difference between DFBZ and BT35-11?

DFBZ is a dedicated explosion-proof bifurcated design; BT35-11 is the Ex version of standard T35-11 sharing identical flange and casing dimensions for direct replacement.

Can DFBZ replace T35-11 without changing ductwork?

BT35-11 is the exact dimensional match for T35-11. DFBZ uses compatible flanges but dimensional submittals should be checked before direct substitution.

Is ExdIIBT4 suitable for combustible dust?

No. Gas markings (IIA, IIB, IIC) apply strictly to flammable vapors. Combustible dust requires dedicated dust certification (e.g. Ex tb / Group III).

Is an explosion-proof fan automatically a smoke-exhaust fan?

No. Hazardous-area protection (Ex) and high-temperature fire rating (280 °C / 30 min) solve different hazards. If both are needed, specify a dual-certified model.

07 / Hazardous Engineering Handoff

Select the Right Explosion-Proof Fan for Your Facility

Send your site hazardous area classification schedule, gas group, temperature class, required airflow, and total pressure — our hazardous application engineers will confirm full certification compliance and provide complete submittal documentation.

Zone 1 / Zone 2 Gas Gas Group IIA / IIB / IIC Temperature Class T4 DFBZ · BT35-11 · BWEX · Ex-DTF GB 3836 / IECEx Non-Sparking Alloy
Request Ex Fan Sizing Go to Selection Center Ask a Hazardous Area Engineer
YONGFAN hazardous area application engineers reviewing explosion-proof submittals
Direct Hazardous Selection Support
GB 3836 Ex certificates, spark clearance sheets & 3D BIM models.
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