Variable Pitch Axial Fans

Howden variable pitch axial fans are used for specialist applications in mining and tunnel ventilation. In the power industry the Variax® fan is used for boiler draught and FGD booster applications in boiler sizes ranging from 100MWe to 1200MWe and beyond.

The Variax^® fan is a constant speed hydraulically controlled VP

axial flow machine that provides a wide range of aerodynamic performance at very high efficiency. Extensive model and full scale testing to AMCA

and VDI

standards has enabled Howden to offer one of the most efficient axial flow fan on the market today.

We offer a wide range of blade materials, with or without erosion shields, several main bearing options, and can supply a number of inlet and outlet configurations and a variety of stall avoidance methods.

The fan is designed for 8000 hours operation per year for 20 years with a minimum of maintenance and a maximum of reliability. Blade replacement can be carried out in-situ, and impeller overhauls can be undertaken without dismantling the fan casing and removing the complete rotating assembly. All maintenance can be carried out on site.

Specialized applications
We engineer our variable pitch axial fans to meet the specific requirements of specialized applications, for example mine and tunnel ventilation. Our fans can be supplied with the following design features:

flow reversal in a range between 40 to 60% of nominal flow achievable by varying the blade pitch or changing the direction of rotation
operation in temperatures up to 400°C for 90 minutes
explosion resistance due to the appropriate material combination for blades and fan casing
output control by speed variation or a combination of variable pitch control and speed control

We use the experience we have gained from a wide range of installations throughout the world to assess the needs of the customer and provide the optimum fan for each application.