The Black Line Tunnel inlet (BLT) from Tulderhof is a tunnel valve made of PU foam. The BLT series is a standard side flap with flanges all around. These are mounted on top of each other, forming a tunnel inlet.
The valves can be easily adjusted with a special fine-tune knob. The pulling force has also been optimized: a five-fold tunnel requires a force of 16 kg. Due to the aerodynamic rounded edges, we achieve 8% more air output with this valve.
The Black Line Tunnel inlet is supplied self-closing as standard. This has the advantage that the valves are always completely draught-proof when closed.
