Flexible Duct Diameter and Fan Connection Checklist

Measure the real connection

Start with the actual fan outlet, hood spigot or equipment collar rather than an assumed nominal size. Record whether the connection is inside or outside diameter, round or non-round, and whether there is room for a cuff and clamp. A small mismatch can create leakage, a crushed hose end or an unnecessary reducer.

Link diameter to the airflow route

Diameter should be reviewed with airflow, installed length, bends, pressure direction and conveyed medium. A flexible duct is more resistant than straight smooth pipe, especially when it is compressed or routed through tight turns. Keep the specification tied to the complete fan and duct system, not a catalogue image.

Give the supplier a usable RFQ

Send the fan or machine connection size, airflow if known, positive-pressure or suction duty, length, route, temperature, end treatment and quantity. This helps a China flexible duct manufacturer recommend a standard size or prepare a custom ducting quotation with suitable cuffs, flanges or reducers.