Fläkt Woods is an industry leader in air movement technology – the company’s expertise in tunnel ventilation ranging from road, rail and metro tunnels to tunnel construction and mining. “Fläkt Woods products have been successfully used in underground projects throughout the world and its AXIJET and JM AEROFOIL product ranges are unrivalled in their technology, innovation and efficiency,” says the company.

Recently Fläkt Woods was called upon for the initial ventilation design on the London’s M25 Holmesdale tunnel. “This is a very restricted tunnel and a Saccardo nozzle system was proposed,” says the company. Previously used in the Channel Tunnel Rail Link, with which Fläkt Woods was also involved, a Saccardo nozzle induces longitudinal airflow in a similar way to an AXIJET longitudinal system, except using several large fans coupled to a nozzle.

Under another recent contract Fläkt Woods supplied ventilation solutions on the Valsassina Tunnel, which connects the Italian city of Lecco to the Valsassina valley. The mixed type ventilation system is said to consist of two large ventilation rooms and 67 of the company’s Jet Thrust Fans, constructed in stainless steel and certified for operation in emergency situations at 400°C for a maximum of two hours. The fans are positioned over the tunnel entrances, along the side roads and near to the slipways.

The peculiarity of this system is the Bione ventilation room, which is said to be unique, as it is not designed on a horizontal plane but vertical. The room occupies a total of four floors and starts at the level of the false ceiling where the ducts are situated, separated for fresh air intake and polluted air extraction.

Serving these ducts are four Fläkt Woods unidirectional Aerofoil JM fans with an impeller diameter of 1600mm, two for each fresh air duct, and two large two-stage JM Aerofoils with an impeller diameter of 2500mm for the extraction of polluted air. The fans are vertically mounted.

Fläkt Woods

Tel: +44 1206 222 549
Web: www.flaktwoods.com/169/ 2756/1


London’s M25 Holmsdale Tunnel The Saccardo system visible at the portal of the Holmsdale Tunnel