Industrial Fan
The right fan for every process gas — engineered for temperature, dust and chemistry.
Process fans are the heart of every drying, gas-cleaning and conveying system. A mis-selected fan — wrong curve, wrong impeller geometry, wrong material — causes surging, erosion, corrosion or premature bearing failure that shuts down the entire plant. Lozzar specifies, sources and integrates centrifugal and axial fans as part of complete process systems: induced-draft fans downstream of scrubbers and bag filters, forced-draft fans feeding dryer burners, recirculation fans for closed-loop drying circuits, and pressure fans for pneumatic conveying. Every selection is backed by a fan curve analysis, a system resistance calculation and a mechanical review covering impeller material, shaft seal, bearing arrangement and drive type.
Fan Types and Selection Principles
Process fans convert mechanical shaft power into kinetic energy and static pressure in a gas stream. The two principal types are **centrifugal fans** and **axial fans**, and the selection between them is determined by the system resistance curve, required pressure rise and gas properties.
**Centrifugal fans** accelerate gas radially outward through a rotating impeller and convert the velocity head to static pressure in a spiral volute casing. They are the dominant choice for process gas applications because they handle high static pressure (500–20,000 Pa), tolerate dust without clogging, and maintain a stable, non-surging operating point across a wide flow range. Three impeller geometries cover the process spectrum: **backward-curved (BC)** blades offer the highest efficiency (80–85%) and non-overloading power curve — the preferred choice for clean or lightly laden gas in dryer and scrubber applications; **radial (paddle) blades** sacrifice efficiency (55–65%) for superior dust tolerance and self-cleaning — selected for high-dust gas (>10 g/Nm³), sticky or abrasive materials, and pneumatic conveying; **forward-curved (FC)** blades give high flow at low pressure and compact size — used for HVAC and ventilation duties, rarely in aggressive process gas.
**Axial fans** move gas parallel to the shaft axis using aerofoil blades. They deliver very high flows at low static pressure (50–2,000 Pa) and are highly efficient (80–90%) in their design range but stall abruptly when system resistance exceeds design pressure — unsuitable for variable-resistance process systems. Axial fans are selected for forced-draught cooling, large-volume recirculation and air supply duties where duct resistance is low and predictable.
Fan performance is characterised by the **fan law triad**: flow Q ∝ speed N; static pressure ΔP ∝ N²; shaft power P ∝ N³. This means doubling fan speed requires eight times the power — a critical relationship for variable-speed drive (VSD/VFD) sizing. The operating point is the intersection of the fan curve and the system resistance curve (ΔP_system = k·Q²); stable operation requires the fan curve to have a continuously falling pressure characteristic (no saddle point) at the design flow.
Quick Reference
Technical Specifications
All parameters are indicative ranges. Final sizing is determined by process simulation based on your specific material and throughput requirements.
Operating Parameters
| Parameter | Value / Range | Note |
|---|---|---|
| Volumetric flow range | 500 – 1,000,000 m³/h per unit | Parallel fan arrays for larger flows |
| Static pressure rise | 50 – 20,000 Pa | Axial: 50–2,000 Pa; centrifugal single-stage: 500–20,000 Pa |
| Gas temperature | -20°C to +600°C | <200°C: standard bearings; 200–400°C: bearing pedestals + cooling; >400°C: water-cooled shaft seals + refractory-lined casing option |
| Dust concentration (inlet) | Up to 200 g/Nm³ | Radial paddle impeller for >10 g/Nm³; BC impeller for <10 g/Nm³ clean/scrubbed gas |
| Fan efficiency (total-to-static) | 55 – 85% | BC impeller: 78–85%; radial paddle: 55–65%; FC: 60–72%; axial aerofoil: 80–90% |
| Shaft speed | 200 – 3,000 rpm | Direct drive (motor-to-fan coupling) or belt drive; VSD standard for dryer duty |
| Motor power range | 1.5 – 2,000 kW | IE3/IE4 motor efficiency class standard; VSD (variable speed drive) for energy saving |
| Impeller material options | CS / SS 304 / SS 316L / Duplex / FRP / Rubber-lined CS | Selected per gas temperature, corrosion, abrasion and ATEX requirements |
| ATEX certification | Zone 21 / Zone 22 (dust); Zone 1 / Zone 2 (gas) | Non-sparking aluminium or SS impeller; earthing; ATEX motor and coupling |
| Noise level (at 1 m from casing) | 75 – 105 dB(A) | Acoustic lagging and inlet/outlet silencers available; <85 dB(A) with silencers |
Impeller Type Selection Guide
| Parameter | Value / Range | Note |
|---|---|---|
| Backward-curved (BC) — clean/lightly-laden gas | η: 78–85%; ΔP: up to 10,000 Pa; dust: <10 g/Nm³ | Non-overloading power curve; best for scrubber ID fan, dryer exhaust after bag filter, boiler FD fan |
| Radial paddle (RP) — high-dust / abrasive gas | η: 55–65%; ΔP: up to 6,000 Pa; dust: up to 200 g/Nm³ | Self-cleaning; Hardox 400/500 wear plates available; for dryer exhaust before filter, conveying fans, cement mill fans |
| Forward-curved (FC) — low-pressure high-flow | η: 60–72%; ΔP: up to 3,000 Pa; dust: <5 g/Nm³ | Compact size for given flow; risk of overloading if system ΔP falls — use only where resistance is predictable |
| Axial aerofoil — large-volume low-resistance duties | η: 80–90%; ΔP: 50–2,000 Pa; flow to 1,000,000 m³/h | Variable pitch blades for flow control without VSD; for cooling towers, large FD/ID duties with low duct resistance |
| FRP impeller — corrosive wet/acid gas | η: 65–78%; T: up to 120°C; pH: 1–13 | For scrubber recirculation fans, HCl/HF/SO₂ service downstream of mist eliminator; no corrosion allowance derating needed |
Need a technical pre-sizing? Send us your material data sheet, moisture content, required throughput and energy source — we return a technical sizing with drum dimensions and energy balance within 2 business days.
→ Send process data on WhatsAppProcess Fan Applications
Reference data from industrial installations. Actual values depend on feed consistency, particle size distribution and required product quality.
| Material | Inlet moisture | Outlet moisture | Particle size | Gas temp. | Industry |
|---|---|---|---|---|---|
| Rotary dryer exhaust fan (ID, before bag filter) | 5–25% v/v H₂O | Same (fan downstream of dryer, upstream of filter) | 0.5–100 µm at up to 30 g/Nm³ | 80–160°C | Food / Feed / Minerals / Chemicals |
| Bag filter induced-draft fan (ID, after bag filter) | 5–20% v/v H₂O | Same (fan handles clean filtered gas) | <5 mg/Nm³ (after filter) | 80–160°C | All process industries |
| Wet scrubber induced-draft fan (corrosive wet gas) | Saturated (100% RH, acid mist) | Saturated (after mist eliminator) | <20 mg/Nm³ acid mist | 40–70°C | Chemical / Glass / Waste / Metal Pickling |
| Spray dryer hot-gas recirculation fan | 0–5% v/v H₂O (partially dried recirculated gas) | Same (closed-loop recirculation) | Low dust — recirculated clean gas | 150–220°C | Dairy / Detergents / Food |
| Pneumatic conveying pressure fan (dense or dilute phase) | <1% v/v H₂O (dry conveying air) | Same | Product entrained in air — up to 20 kg/kg air | Ambient to 80°C | Plastics / Pharma / Food / Minerals |
| Cement kiln cooler vent fan (high-temperature, high-dust) | <2% v/v H₂O | Same | 10–200 µm at up to 100 g/Nm³ | 200–400°C | Cement / Lime |
| Fluidized bed dryer fluidization air fan (forced-draft) | Ambient air (0–80% RH) | Same (after heating) | Clean air (no dust) | Ambient → heated to 80–200°C | Chemicals / Pharma / Food / Minerals |
| High-temperature hot-gas fan — rotary kiln / incinerator | 10–30% v/v H₂O | Same | 1–50 µm at 5–30 g/Nm³ | 300–600°C | Waste / Cement / Lime / Pyrolysis |
Don't see your material? Send us your process data and we'll provide material-specific sizing.
Fan Configurations
Centrifugal — Backward-Curved (BC)
Single-inlet or double-inlet centrifugal fan with backward-curved or backward-inclined aerofoil blades. Non-overloading characteristic: power reaches a maximum near design flow and falls at higher flows — safe against motor overload if system resistance drops. η_ts = 78–85%. Steel or SS impeller with anti-abrasion liners for modest dust loads. VSD drive standard for dryer and scrubber duty. ATEX Zone 22 with non-sparking options. Operating range: 500–500,000 m³/h, 500–10,000 Pa, to 300°C standard.
Centrifugal — Radial Paddle (RP)
Radial flat or curved-paddle impeller with large blade passage width — allows dust and coarse particles to pass without clogging. Self-cleaning geometry: particle impact angle minimises adhesion. Replaceable Hardox 400/500 wear liners on impeller blades and inlet cone for abrasive service. η_ts = 55–65% (lower than BC, but acceptable for the duty). Shaft seal options: labyrinth, mechanical, or purge-air for high-dust applications. Handles inlet dust concentrations up to 200 g/Nm³. Operating range: 1,000–300,000 m³/h, 200–6,000 Pa, to 400°C with water-cooled bearings.
Corrosion-Resistant Fan (FRP / SS 316L)
Centrifugal fan with FRP (glass-fibre reinforced polypropylene or vinyl ester) or SS 316L impeller, casing and inlet cone. Designed for continuous duty in saturated acid or alkali gas downstream of wet scrubbers, where carbon steel would corrode within weeks. FRP option: pH 1–13, T ≤ 120°C, non-sparking (no ATEX impeller requirement in scrubber service). SS 316L option: pH 0–14, T ≤ 300°C, ATEX Zone 21 with non-sparking coating. Rubber-lined carbon steel casing available as alternative to full FRP for large flow units. Mechanical seal or packed stuffing box; grease-purged labyrinth seal for most wet service.
When to Specify a Process Fan Through Lozzar
Your dryer, scrubber or filter requires a dedicated ID or FD fan as part of the gas circuit
Lozzar co-engineers the fan with the process system — curve, duct and drive are matched by the same team that designed the dryer or scrubber. No interface risk.
Gas temperature exceeds 200°C or dust concentration exceeds 10 g/Nm³ and a standard fan vendor recommends a generic catalogue selection
Request an engineered selection: bearing arrangement, shaft seal, impeller geometry and material must be specified for the actual gas conditions — catalogue defaults will lead to premature failure.
Energy cost is significant and fans are running on a fixed-speed motor with damper control at variable process load
Retrofit VSD: reducing fan speed by 20% saves 49% of shaft power. For a 75 kW fan running 6,000 h/year, this is €15,000–25,000 annual saving at European electricity rates.
ATEX certification is required and the fan vendor cannot provide a complete ATEX equipment dossier
Lozzar provides ATEX-rated fans with a complete equipment dossier: zone classification, ignition hazard assessment, non-sparking impeller certification, motor ATEX certificate and earthing continuity test report.
When NOT to Request a Standalone Fan
Simple HVAC or building ventilation duty — no process gas, no dust, no corrosion, standard ambient temperature
Gas circuit requires particulate separation — a fan alone cannot clean the gas
Gas contains acid gases (HCl, SO₂) that must be removed — a fan only moves the gas, it does not absorb pollutants
Very high pressure rise required (>20,000 Pa) — centrifugal fans cannot achieve this without multi-staging or a blower/compressor
Not sure which dryer is right for your process? We'll review your specifications and recommend the optimal solution.
Ask a technical question →Frequently Asked Questions — Industrial Fans
Fan duty is defined by two parameters: volumetric flow Q (m³/h) at operating conditions (not at standard conditions) and total static pressure rise ΔP_ts (Pa). The operating flow is derived from the process mass balance: if a dryer evaporates 1,000 kg/h of water and uses air at inlet T=120°C, the exhaust volume is calculated from the psychrometric mass balance and converted to actual m³/h at fan inlet temperature and pressure. The static pressure is the sum of all resistances in the duct system: inlet duct + cyclone ΔP + bag filter ΔP + outlet duct + discharge stack. Typical values: inlet duct 200–500 Pa, cyclone 500–1,500 Pa, bag filter 800–2,500 Pa, outlet 100–300 Pa. Total: 1,600–4,800 Pa for a complete dryer gas circuit. Add 10–15% design margin to the calculated duty and select a fan with its BEP within this range. Gas density must be corrected for temperature: ρ = ρ_STP × (273/T_K) × (P/101,325), since fan pressure rise scales linearly with density.
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ID fan is always required downstream of a bag filter to overcome filter pressure drop (800–2,500 Pa) — specify fan and filter together for matched performance guarantee
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Wet scrubber ID fan must handle saturated acid/alkali gas — FRP or SS 316L impeller required; co-specify with scrubber to match resistance curve
View productCyclone Separator
Cyclone adds 500–2,500 Pa to system resistance — include in fan duty calculation; fan placed after cyclone sees lower dust load, allowing BC impeller instead of radial paddle
View productRotary Dryer
Every rotary dryer requires a dedicated exhaust fan — radial paddle impeller for pre-filter duty, BC impeller if fan is placed after cyclone and bag filter
View productRequest a Quote for This Equipment
Include in your enquiry:
- →Volumetric flow rate (m³/h at operating conditions, NOT Nm³/h unless specified)
- →Fan inlet temperature (°C) and altitude above sea level (m)
- →Required static or total pressure rise (Pa)
- →Gas moisture content (%v/v or dew point °C)
- →Dust concentration at fan inlet (g/Nm³) and particle d50 (µm)
- →Gas chemistry: any acid gases (HCl, SO₂, HF ppm), pH of condensate
- →Duty: induced-draft (ID) or forced-draft (FD)? Continuous or batch?
- →Drive type: direct, belt or VSD? Available motor voltage (V/Hz)
- →ATEX zone classification required? (Zone 21 / Zone 22 / Zone 1 / Zone 2)
- →What equipment is upstream and downstream of the fan in the gas circuit?