FBD Series Flameproof Counter-Rotating Axial Auxiliary Fan

I. General Structure

The FBD series fan consists of an inlet collector, first-stage assembly (casing, impeller, and motor), second-stage assembly (casing, impeller, and motor), and a diffuser.

The entire unit is welded from steel plates, with internal sound-absorbing material and explosion-proof structural design for reliable safety.

A key feature is the contra-rotating structure: two flameproof motors of equal power independently drive the impellers—stage I rotates clockwise, stage II counterclockwise—achieving efficient contra-rotating airflow.

1— Inlet Collector  2— First-Stage Assembly  3— First-Stage Motor  4— First-Stage Impeller

5— Second-Stage Impeller  6— Second-Stage Assembly 7— Second-Stage Motor  8— Diffuser

Figure 1: FBD Series Flameproof Counter-Rotating Axial Auxiliary Fan

II. Working Principle

Air Intake & Acceleration
Airflow enters axially through the inlet collector. The collector’s curved inlet and guide cover effectively reduce intake resistance, providing smooth, even airflow to the first-stage impeller.

First-Stage Function
Driven by its motor, the first-stage impeller accelerates the airflow and imparts an initial directional change. The first-stage casing supports the impeller and motor, while also serving as a silencer to reduce noise.

Second-Stage Function
The accelerated, redirected air then enters the second-stage assembly. The second-stage impeller, driven by its motor and rotating in the opposite direction (contra-rotating), provides secondary acceleration and further redirects the airflow. The casing is structurally and acoustically similar to the first stage.

Diffusion & Discharge
After the second-stage acceleration, air enters the diffuser, consisting of a diffusion tube and guide cover. This reduces outlet resistance, enhances discharge efficiency, and further suppresses noise. The airflow is then smoothly expelled axially, completing the ventilation process.

III. Key Component Analysis

• Inlet Collector: Curved intake and guide cover minimize intake resistance and improve intake quality.

• First/Second-Stage Assemblies: Each includes casing, impeller, and motor, enabling two-stage contra-rotating acceleration for greater airflow and pressure. Acoustic lining reduces noise.

• Diffuser: Comprising a diffusion tube and guide cover, it lowers exhaust resistance, increases air kinetic energy utilization, and also serves as a silencer.

IV. Structural & Performance Advantages

• Contra-rotating dual-impeller design for high efficiency, long air delivery, and significant energy savings

• Fully flameproof structure, ensuring high safety for coal mines, metal mines, and other explosive gas environments

• Low-noise acoustic design for a more comfortable work environment

• Wide range of models to meet different roadway and face ventilation needs

• Easy maintenance, long service life (≥5 years), and safe operation up to 13,000 hours

Technical Performance and Overall/Installation Dimensions Table of Ventilation Fan