The access door is also used as an inspection hatch for rectangular ducts. To the access door belongs a fixing frame, which is attached to the rectangular duct. This is normally done with blind rivets through the folded-down edge of the done frame. It can also be provided with folding tabs on request.
It is easy to remove the access door from the fixing frame by using over-centre catches. In the insulated versions, the inner side will always be in level with the innermost boundary line of the duct, irrespective of whether the duct is insulated internally or externally. The table below shows the insulation thickness of the door at different duct insulation alternatives.
The door should not be placed closer than 50 mm from the nearest side of the rectangular duct.
Maximum square measurement of the access door is 1170×1170 mm.