Air · Primary Ventilation
Corrosion-free polyethylene vasse cones, self-closing fan doors, pedestrian vent doors and drop-board regulators that complement the Polyduct range — non-corrosive, UV-stable and long-lived.
The range
Each unit is fabricated to your shaft, drift or fan-case geometry — standard configurations shown, custom on request. Tap any image to enlarge.
A bellmouth intake at the fan that slows incoming air. Built as a split-flange cone in modular sections for road transport and site assembly — also catalogued as the Modular Vasse / Evase.
A fabricated HDPE inlet transition at the fan, made to suit your fan-case geometry. Corrosion-free and UV-stable.
Bolts to the fan flange and opens or closes with airflow, closing to limit back-flow when the fan is off. Fan pressure opens the doors — no counterweights.
HDPE inner and outer casings around a punched inner cylinder and high-tech sound foam. Built to about 1.5× the fan diameter for maximum noise reduction, with 20 mm HDPE end flanges bolted through the existing steel-flange P.C.D. Detachable bell or bag-cone ends available. The slim sub-50 mm wall keeps the silencer within the fan-flange diameter.
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Custom diameters fabricated to your fan case. Our engineering team prices from your site details and drawings.