| 摘要 |
<p>This seal is designed to be interposed between the collar of a manhole and a vertical tube for access to an external pipeline, the inside diameter of which may have two magnitudes. According to the invention, it includes a cylindrical skirt (9) with an outer collar (11) mounted over the top of it, this outer collar being designed to bear against the upper end of the joining tube, this cylindrical skirt (9) itself being composed of three parts, an upper part (9a) whose thickness, in the compressed state, corresponds substantially to the difference in radii of the collar and of the bore of a vertical connection tube of small diameter, a lower part (9b) whose thickness, added to that of the upper part (9a) and in the compressed state, corresponds substantially to the difference in radii of the collar and of the bore of a connecting tube of large diameter and, between these two parts (9a, 9b), an intermediate part (9c) of very small thickness, to allow the lower part (9b) to be turned up over the upper part. <IMAGE></p> |
