Protan Ventiflex Duo is a concept developed to transport air through narrow passages or in tunnels with restricted height, without compromising air flow. A large main duct is replaced with two standard ducts with a smaller diameter, together called a duoduct.

The duoduct is installed by means of a common wire suspension, and the two parallel ducts press against the roof when they are full of air. The roof height thus increased by up to 40% as compared with one main duct.

Protan Ventiflex Duo has a larger cross-section than other similar systems, which means lower energy consumption for the same installation height and fan output. It also delivers more air with the same fan output.

The two separate ducts can function independently, and the system’s secure coupling has extremely low friction. The Protan Ventiflex Duo concept has been developed in such a way that it can use all Protan couplings. In addition, it can be installed near the roof of a tunnel because the suspension system is place between the two independent ducts.