ISO 7807:1983

Air distribution — Straight circular sheet metal ducts with a lock type spiral seam and straight rectangular sheet metal ducts — Dimensions

Specifies dimensional characteristics of straight elements of circular and rectangular ducts. Applies to air ducts used in heating, ventilating and air conditioning. Tabulates recommended (R 10 series) and additional sizes for circular ducts (tables 1 and 2) as well as recommended sizes for rectangular ducts (table 3).