Axial Flow Fans General Information

Introduction

This section details the performances of a wide range of axial flow fan types:

Duct Mounted Axial Fans

• AP Series - direct driven
• APS Series - direct driven, smoke spill
• APB Series - belt-driven
• BFA Series - bifurcated, direct driven

Wall Mounted Fans

• SQ Series - square plate, direct driven

Axial Roof Units

• RDE/RDLE Series - downflow cowl, exhaust
• RDS Series - downflow cowl, supply
• RVE/RVLE Series - vertical discharge
• RSS/RSSL Series - vertical discharge, smoke spill
• HC Series - high capacity, vertical discharge
• SS Series - smoke spill

Fan diameters range from 315mm to 2000mm. Performance curves for the AP series in Type D Installation are shown on pages C-12 to C-24. Other fan types incorporate casings that impact performance; the Fantech Product Selection Program accounts for these losses.

Test Standards

The International Standards Organisation (ISO) established a standardized fan test code with ISO5801:1997, replacing BS848:Part 1, 1980. Elta 1000 Series fans were tested to BS848:Part 1, 1980, and Elta 1400 and 2000 Series to ISO5801:1997. All three series were tested for sound performance to BS848:Part 2, 1985.

A key difference between standards is the installation types (A, B, C, D), which affect performance variation:

• Type A: Free inlet, Free outlet
• Type B: Free inlet, Ducted outlet
• Type C: Ducted inlet, Free outlet
• Type D: Ducted inlet, Ducted outlet

Both BS848:Part 1, 1980 and ISO5801:1997 reflect updated measurement techniques. Testing to later standards can result in performance differences of up to -5% in volume, -10% in pressure, -5% in efficiency, and +2 to 6dB in noise compared to pre-1980 standards. These differences are due to test methods, not product variations.

Performance Variations

Achieved fan performances can differ from test performances due to:

1. System Irregularities: Abrupt changes near the fan can affect air uniformity. Good design practice ensures uniform inlet air for optimal performance. Refer to "Do's and Don'ts" tips for guidance.
2. Internal Fan Elements: Components like large motor junction boxes, belt drive stacks, or excessive blade tip clearances can alter performance.

Forms of Running

Main series tests used Form B units, with comparative tests on Form A. Performance differences are most noticeable on the outlet side, emphasizing the need for correct inlet ducting or cones.

Down-Stream Guide Vanes (DSGV)

Axial flow fans impart rotational motion ('swirl') to the air. DSGVs convert this swirl into static pressure, increasing static pressure by 10%-25% and improving efficiency without requiring additional fan power. They are most effective at pitch angles over 20° and add 1-2dB to sound levels.

Multi-Stage Axial Flow Fans

Multi-stage axial fans with contra-rotating impellers are available up to 2000mm diameter. A two-stage assembly provides approximately 2.4 times the pressure of a single-stage fan and increases sound levels by 8-10dB. To select a contra-rotating fan, divide the specified static pressure by 2.4. Refer to Fantech or the Product Selection Program for complete selections.

Elta Impeller Range

Fantech's Elta impeller ranges utilize advanced technology for enhanced pressure, efficiency, and reduced noise. Key ranges include:

• Elta 1000: 315-1000mm diameter (150 or 250mm hubs)
• Elta 1400: 800-1400mm diameter (255 or 350mm hubs)
• Elta 2000: 1250-2000mm diameter (400 or 550mm hubs)

For specialized applications like mine and tunnel ventilation, consult Fantech sales engineers.

Impeller Specifications

Stress limits vary by material. The Fantech Product Selection Program can provide solutions with higher pitch angles. All hubs use Fantech TECH-LOCK® taper bushes for easy fitting and removal. Impellers are assembled with high-tensile, zinc-plated set screws and self-locking nuts.

Operating Speeds and Temperatures

Impeller performance is influenced by vibration, torques, and temperature cycles in OEM applications. The table below provides a guide; use the Fantech Product Selection Program for precise figures.

*Up to 1000mm diameter. **Applicable to 20°C. ***1400 Series only. #1400 Series = 800mm to 1400mm; 2000 Series = 1250mm to 2000mm.

Reversal of Air Flow

Fans with three-phase motors can reverse airflow by reversing motor rotation. This results in approximate performance impacts:

• Air flow reduction: -30%
• Pressure reduction: -55%
• Power reduction: -25%

Truly Reversible: Equal volume flow in both directions is achievable through blade reversal during assembly. This impacts performance compared to standard settings:

• Air flow reduction: -15%
• Pressure reduction: -25%
• Power reduction: -20%

Construction

Axial fan casings are constructed from pre-galvanised or hot-dip galvanised steel (AS/NZS4792:2006). Standard casings fully enclose the impeller and motor, featuring weatherproof external terminal boxes. Motors are wired via flexible conduit with a separate earthing screw. Inspection hatches or sight holes are fitted on fans 1000mm diameter and over, or on smaller fans as an option. Flameproof or increased-safety motors are wired externally for client connection to their own terminal boxes.

Axial Flow Fan Range - Duct Mounted

Descriptions of various duct-mounted fan series:

• Direct-drive - AP Series (315 to 2000 mm): Available in a wide range of speeds. Flameproof or special application motors can be fitted.
• Direct-drive - APV Series (315 to 2000 mm): Designed for vertical mounting with integral outriggers.
• Direct-drive - APS Series (315 to 2000 mm): For smoke spill applications, tested to Australian Standards AS/NZS1668.1:1998 and AS4429:1999.
• Belt-drive - APB Series (315 to 2000 mm): Suitable when the motor must be outside the air stream. Account for pressure loss: no extra loss for open belts; 5% for sealed belt guards.
• Bifurcated - BFA Series (400 to 1250 mm): Designed for toxic, noxious, abrasive, and hot gases. Maximum continuous operating temperatures are 100°C for aluminium impellers and 70°C for GRP. Higher temperatures are possible with special builds. Specific allowances for the central shroud are required based on size (1.0 x pdF for 400-560mm, 0.7 x pdF for 630-1250mm).

Images of various duct-mounted axial flow fans are presented.

Axial Flow Fan Range - Wall Mounted & Roof Mounted

Wall Mounted

• Square Plate - SQ Series (315 to 1250 mm): Features a bell-mouth entry. Air flow direction must be nominated at order. Type A installation is required. Square plates are heavy-gauge steel, hot dip galvanised.

Roof Mounted

• Alpha & Beta Industrial - RDLE, RVLE & RSSL (500 to 1000 mm): Available in vertical and downflow configurations, including a vertical exhaust smoke-spill model (RSSL). Cowls are plastic; windbands are galvanised steel. All have pressed galvanised steel bases.
• New Generation Series - RDE, RDS, RVE & RSS (315 to 1250 mm): Vertical and downflow configurations. Includes downflow supply (RDS) and vertical exhaust smoke-spill (RSS) models. Galvanised steel bases have bell-mouth entries.
• High Capacity and Smoke-Spill Series - HC & SS (500 to 1800 mm): HC series is for vertical discharge; SS series is for smoke-spill applications. Both feature hot dip galvanised steel construction.

Flameproof or special application motors can be fitted to roof units. Refer to "Smoke-Spill Applications" on page C-8. Use the Fantech Product Selection Program for accurate selections.

Images of wall-mounted and roof-mounted axial flow fans are presented.

Smoke-Spill Applications

Smoke-spill fans must comply with Standard AS4429:1999 and AS/NZS1668.1:1998. Fantech conducted extensive tests for airflow and temperature. Fans are available in diameters from 315mm to 2000mm, compliant with standards for various conditions:

• 200°C for two hours
• 200°C for four hours
• 250°C for four hours
• 280°C for 0.5 hours
• 300°C for 0.5 hours
• 300°C for two hours

Discharge Damper Fail-Open Latching: Standards require specific damper functions in unsprinklered buildings. Fantech offers manual release types (requiring manual closing) for dedicated smoke spill fans, and electro-mechanical types (automatic closing) for dual-purpose ventilation/smoke-spill fans. Fantech holds provisional patents for these designs.

Consult Fantech sales engineers for wiring requirements and additional information.

Computer Selection

The Fantech Product Selection Program offers:

• Fan selection
• Attenuator selection
• Acoustic analysis
• Project schedule building
• Downloadable drawings (dwg/dxf) and Revit models
• Easy updates from the Fantech website

Contact Fantech Sales Offices for a CD copy.