Abstract: The head (11) (40) of a belt conveyor roller is press-fit into a cylindric shell (10) of the roller. The head (11) (40) defines a bearing chamber (12) for a frictionless bearing (14-15; 42) which is closed by a ring assembly (21, 29) welded to the head and provided, in the embodiment disclosed, with a stainless steel lamella (33, 59) the opening (60) of which bites into the resilient outer cylindric surface (61) of a hub section (28, 53), to provide a virtually hermetical enclosure of the bearing chamber (12, 41) thus increasing the safety of the operation by isolating the possible point of ignition or explosion on seizure of the bearing (14-15; 41) of the roller. The roller equipped with the assembly of the present invention thus presents a further improvement in the art of belt conveyors for use in hazardous environments.