Ventilateurs
Industriels — Base de Connaissances

Operating Principle: Air enters and exits the fan parallel to the rotating shaft. The impeller blades impart both kinetic energy (velocity) and static pressure rise to the air stream. Guide vanes after the impeller recover some of the kinetic energy as additional static pressure, improving efficiency.

Key Characteristics:

• Flow range: 0.5–500+ m³/s — the widest airflow range of any fan type
• Pressure range: 50–2,500 Pa — suitable for low to medium resistance systems
• Efficiency: 60–85% depending on blade design (aerofoil blades achieve highest efficiency)
• Blade types: Fixed pitch (simplest, most reliable) / Adjustable pitch (flexible, field-tunable) / Variable pitch in motion (complex, maximum control)

Typical Applications: General factory ventilation | Cooling towers and heat exchangers | Tunnel and metro ventilation | Paint spray booths | Car park smoke extraction | Data center cooling | Agricultural ventilation

Operating Principle: Air enters the impeller eye axially, is captured by rotating blades, and is thrown outward by centrifugal force. The scroll-shaped housing collects the high-velocity air and converts kinetic energy to static pressure through the expanding volute.

Impeller Types and Their Applications:

• Forward-Curved (FC): Many small blades curved forward. Compact, low noise, low tip speed. Best for: HVAC air handling units, fan coil units, residential ventilation. Pressure: 100–1,000 Pa.
• Backward-Curved (BC): Fewer blades curved away from rotation. High efficiency (80–88%), non-overloading power curve. Best for: Industrial process exhaust, dust collection, clean air applications. Pressure: 500–5,000 Pa.
• Radial (Straight-Blade): Simple flat radial blades. Handles dust, fibers, and particulate-laden air without clogging. Best for: Material conveying, grinding dust, wood chips. Pressure: 1,000–10,000 Pa.
• Airfoil: Hollow aerodynamic blades like aircraft wings. Highest efficiency (up to 92%). Best for: Large HVAC systems, clean air processes, energy-critical applications.

Typical Applications: Dust collection and baghouse systems | Boiler forced/induced draft | Paint booth exhaust | Chemical fume extraction | Cement plant processes | Mine ventilation shafts | Tunnel ventilation (high-pressure sections)

Operating Principle: A jet fan discharges a high-velocity air stream (15–35 m/s) through an optimized nozzle. This jet transfers momentum to surrounding air through entrainment — each fan can move 10–15× its own airflow volume. Fans create a "curtain" of moving air that pushes from fresh air intakes toward exhaust extraction points.

Key Advantages over Ducted Systems:

• Space: No ductwork — saves 300–500 mm of ceiling height, increasing sellable parking area
• Energy: Sensor-controlled operation — fans run only when CO/NOx levels demand it (typically 20–40% duty cycle)
• Safety: Superior smoke control — creates directional smoke-free paths for evacuation and firefighter access
• Flexibility: Easy to add or relocate fans if usage patterns change

Typical Applications: Underground and multi-story car parks | Loading bays and service yards | Bus and coach stations | Enclosed transport interchanges | Warehouse cross-ventilation

Operating Principle: Mixte flow impellers feature conical hub shapes and specially curved blades that accelerate air both axially and radially. This hybrid flow pattern generates higher pressure than pure axial fans while maintaining a straight-through airflow path — eliminating the need for scroll housings.

Key Characteristics:

• Flow: 1–50 m³/s — covers the mid-range between small axials and large centrifugals
• Pressure: 200–1,500 Pa — handles moderate system resistance in ducted applications
• Efficiency: 70–82% — better than axial at pressure, not as high as BC centrifugal
• Noise: Typically 5–8 dB(A) quieter than equivalent axial fans due to guided airflow
• Form factor: In-line cylindrical design — ideal for direct duct integration

Typical Applications: Smoke extraction shafts in high-rise buildings | Staircase pressurization systems | Kitchen exhaust (high-temperature) | Car park ducted ventilation | Tunnel service galleries | Industrial process exhaust

Operating Principle: Large-diameter axial impellers (900–2,800+ mm) with aerodynamically optimized blades drive air through tunnels at controlled velocities. Fans can be configured for longitudinal ventilation (air moves along tunnel axis), transverse ventilation (air supplied/extracted through separate ducts), or semi-transverse systems combining both approaches.

Critical Conception Requirements:

• Reversible operation: Tunnel fans must be able to reverse airflow direction within 60–90 seconds — critical for fire scenarios where evacuation direction may change
• Temperature rating: Typically F250 (250°C/2h) or F400 depending on fire load. Motor and blade materials selected for thermal stability
• Structural integrity: Blades designed with safety factors for high tip speeds (up to 100 m/s). Fatigue analysis for 20+ year service life under cyclic loading
• Noise attenuation: Integrated silencers achieving 15–25 dB(A) reduction for environmental compliance
• Redundancy: N+1 or N+2 configuration standard — no single fan failure compromises safety

Typical Applications: Road/highway tunnels (longitudinal & transverse) | Metro/subway tunnels | Railway tunnels | Underground stations | Utility and cable tunnels | Underground military installations

This is the most critical certification for life safety fans. The fan is placed in a furnace following the ISO 834 time-temperature curve. It must run continuously for 2 hours while exposed to rated temperatures.