Fitting for insulated duct

Claim 1

A tubular fitting assembly adapted for end-to-side panel attachment to a duct whose side panels are formed of relatively thick but somewhat fragile thermal insulating material and which has a generally rectangular aperture cut therein to receive the fitting, said assembly comprising a tubular body having a rectangular end portion inserted into the duct aperture, said end portion being defined by a flange extending outwardly around three sides of the rectangular perimeter of the fitting and spaced from the end margin of the fitting by a distance substantially equal to the duct panel thickness adjacent the duct aperture so that said flange bears against the outer face of the duct panel, an integral tab extending outwardly from the end margin of the section of said end portion forming the fourth side of the rectangular perimeter of the fitting so as to closely overlie the adjacent inner face of the duct panel, and a member which is generally L-shaped in cross-section, one of its leg portions being formed to receive and hold a section of the marginal area of the inserted portion of the fitting, said member being manually applied to the fitting margin by access through the tubular fitting after it has been inserted in the duct aperture, and said member being positioned diametrically opposite said tab with the other of its leg portions closely overlying the adjacent inner face of the duct panel to thereby secure the fitting to the panel.