| 摘要 |
PURPOSE:To enable a smoke insulatio net to be easily cleaned while the net is not removed from a ventilation pipe in a case of a vent hole with the smoke insulation net of a ventilation pipe for an underground tank by installing the net at its lower section in such a way that no projection is made on the attaching surface of the pipe in the lower side of the net. CONSTITUTION:A smoke insulation net 11 is installed at its lower side by fitting a hold spring 13 onto a spring groove 9 on the attachment 7 to a ventilation pipe. The attachment 7 is screwed in with the external thread of the ventilation pupe 3. This configuration does not include any projected portion over the connecting section B with the smoke insulation net 11. Accordingly, this configuration enables the smoke insulation net 11 to be cleaned by pulling the net 11 down with the holding spring 13 removed. This configuration enables the smoke insulation net to be easily cleaned without removing the net from the pipe. |
