Why this ducting earns its place
Between the lightweight 350 mm and the heavy-duty 450 mm, 400 mm ducting strikes the practical middle ground for most commercial kitchens. It's large enough to handle multi-appliance extraction without the back-pressure that makes systems noisy and inefficient, yet compact enough that routing it through a tight kitchen doesn't become a structural puzzle.
At 3 kg per metre, it carries real weight — 1000 mm lengths need solid mounting — but it's still light enough that standard commercial brackets and hangers do the job. Aluminium construction means it resists the thermal shock of hot extraction air cycling through and stands up to grease vapours without corrosion creeping through. When you're running extraction 12+ hours a day, durability compounds: a 400 mm system that holds up for five years is cheaper and less disruptive than swapping out a corroded steel equivalent.
Sizing ducting right matters. Too small, and you fight pressure drop and noise. Too large, and you're paying for capacity you don't need, and airflow velocity drops (weaker capture at the cooking zone). 400 mm is the "just right" diameter for a single cooking station pushing moderate to high volume — a bank of fryers and a grill, say — or for the main trunk when several smaller lines merge.
