<p>The sliding fire-retardant and or smoke-proof door unit is driven by an electric motor and control. The drive mechanism is contained in an enclosed heat-resistant or smoke-proof compartment (60). The sliding leaf has a door panel of a traditional revolving door seal or at least components of a seal etc. The compartment containing the drive mechanism is a traditional case with heat-resistant or smoke-proof cladding, coating, seal etc. Fixed or automatically controlled movable seals are positioned between the sliding leaf and outer door frame and or mechanism-compartment.</p>
