Dual purpose dimple for HVAC circular ductwork
Sealing HVAC ductwork along its joints to reduce air leakage is achieved by the combination of a gasket and mechanical locking mechanisms.
1. A circular sheet metal duct comprising:
(a) sheet metal formed into the shape of the circular duct having a female end, a male end, and a longitudinal snap locking mechanism to join the ends of the sheet metal to form the circular duct;
(b) locks formed into the longitudinal snap locking mechanism, the locks having a frequency of greater than two inches; and
(c) a notch formed at the female end of the circular duct by eliminating a portion of the longitudinal snap locking mechanism extending from the female end inwardly to a depth that the male end enters the female end.
2. A circular sheet metal duct as recited in claim 1 including:
(a) a push-lock female transverse positioning lock; and
(b) a push-lock male transverse positioning lock.
3. A circular sheet metal duct as recited in claim 2 including a gasket on the female end that seals the connections of the duct.
4. A circular sheet metal duct as recited in claim 3 wherein the push-lock female transverse positioning lock is a dimple.