Atex fans

ATEX Compliant Axial Fans

• 315-1600 mm diameter
• Volume flow up to 65 m3/s
• Static Pressures up to 2000 Pa
• 800mm up to 2900 rpm; 1400 mm up to 1450 rpm and 1600 mm up to 960 rpm
• Fully adjustable die cast aluminium impellers; X-ray inspection
• Long short mild steel casing variants - hot dipped galvanised after manufacture
• Tested to ISO 5801
• Motor protection IP55
• High Energy efficiency - AMCA Certified
• Low installed noise levels
• Multiple blade configurations for optimum performance to duty
• Multi-stage available for higher pressure development

The ATEX Impact on Performance of Axial fans

The construction of axial fans to comply with ATEX may have a profound effect on the performance of the fan when compared with fans for use in safe environments.

Normally axial flow fans are designed to 0.25% tip gap (as a % of diameter); ATEX construction requires a minimum running clearance of up to 1% of diameter (minimum 2mm) or 10% of shaft diameter.

The following references quantify the impact the increased clearance has on fan performance:

Daly, Woods Practical Guide to Fan Engineering, suggests, in a table, that a tip gap of 1% reduces the pressure development to 75% that of standard, i.e. an addition of 33% to the calculated resistance is necessary for fan selection.

Bleier, Fan Handbook, Selection Application and Design, MacGraw Hill, presents his results graphically and these indicate 65% pressure development at 1% compared to 0.25%. i.e. an addition of 54% to the calculated resistance is necessary for selection. In addition he suggests that up to 10dB needs to be added to the noise level.

Hunnaball, Journal of Building Acoustics, Control of Axial Flow Fan Noise By Design, presents graphical results indicating 73% pressure development, for 1% compared to 0.25%, i.e. an addition of 38% to the calculated resistance is necessary for selection. +4dB to noise level is also indicated.

Lack, IMechE Fan Conference, suggests that the available pressure with the increased ATEX tip gap of 1% is reduced to approximately 67% of pressure, therefore a 50% increase to the required pressure at selection is required to meet the duty. Fan noise also increases due to the interaction at the impeller tip by between 5-15 dB.

Recent tests at Fläkt Woods concur with the aerodynamic results of Bleier and gave similar acoustic results to Hunnaball.