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Variax® Fans
The Variax® variable pitch axial fan combines one of the highest efficiency levels available today with an exceptionally flexible, customer focused design, manufacturing and aftermarket service. With almost 3000 units soldworldwide, the Variax® fan is the proven, reliable and robust choice across awide range of applications.

Key Benefits

  • One of the highest efficiency levels available in fan technology
  • Exceptional design standards to make it easier for customer operation and monitoring
  • Customer focussed manufacturing and aftermarket support teams
  • Modern high-pressure blade profiles have significantly reduced the size of the fan needed to satisfy a given duty.

Standard features

  • Blade design and aerodynamics selected to maximise performance
  • Oil lubricated blade bearings
  • High efficiency Variax(R) hub as standard
  • Hydraulic cylinder uses a continual flow of oil through the system even when the blade position is constant
  • Guide vanes custom designed for the application
  • Roller mounted diffuser for easy maintenance access
  • The hub and the blades are separately balanced before the impeller unit is assembled
  • Main bearings can be supplied as either roller bearings or sleeve bearings depending on the individual project.

Optional features

  • Single and two-stage versions designed depending on pressure and volume requirements
  • Choice of lubrication system configuration
  • Choice of main roller bearings to suit the project (roller bearings or sleeve bearings).
Detailed specifications

Our possible combinations of blade profile, impeller diameter and material, hub design and size produce a choice of many thousands of configurations.  In addition, we can design Variax® fans for vertical as well as horizontal alignments, and turn the inlet box to suit particular installations.  Specific challenges, such as the complex C-position fans required for flue gases with temperatures close to the acid dew point, are well within our experience.

Designed for pressures of 300 Pa/1 to 15,000 Pa/120 InWG at volumes between 25m3 and 1600m3 per second /50,000 ACFM and 3,400,000 ACFM. 

Designed for pressures of 1500 Pa/6 InWG to 30,000 Pa/120 InWG at volumes between 15m3 and 1600m3 per second /32,000 ACFM and 3,400,000 ACFM.  In two-stage VARIAX® fans, the inlet box is also mounted on rollers and tracks to allow access to the first stage impeller unit while the moving diffuser gives access to the second stage.


VARIAX® fans are found in a wide spectrum of situations where high volumes, high pressures and precise flow control are required, and where reliability and continuous running for months on end are demanded. They are the fans of choice in critical applications within the power industry, where they are used in both primary air (PA fans), forced draught (FD fans) and induced draught (ID fans) positions including boiler draught and FGD and SCR booster applications.

  • Primary Air (PA)
  • Induced Draught (ID) 
  • Forced Draught (FD)
  • Booster applications - FGD and SCR
Spare Parts

The VARIAX® fan is the subject of continual research and development, and the interchangeability of parts makes it possible to retrofit, adapt and upgrade with ease. For example, the recent super high pressure blade profile brought a pressure increase of up to 30% while raising the flow by up to 15% and allowing a smaller hub.

For every VARIAX® installation we maintain a complete, detailed record of specification and any subsequent maintenance or retrofits, to allow us to offer a guaranteed spares and service programme.We can carry out regular monitoring and inspections as well as offer a troubleshooting and emergency service.

All VARIAX® fans are designed with rolling diffusers for ease of maintenance, and only a minimum of strategic spares need to be held on-site.  Replacing blades is straightforward, with no need to rebalance the rotor.

Click here for more information about the parts and services that we offer.

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