| 摘要 |
The security trap door (1) for a purifying station has a frame (2) sealed into the ground during installation. A cover (3) is hinged (7) to close the opening and has a handle (24). The trap door has a partial obturator (8,10,11,12) to spontaneously partially close the opening cover to prevent an operative from falling into the station. There can be a grill (8) positioned below the cover, and stops (10-12) to limit the opening angle of the grill. |
