System for clearing sediment in underground pipes has a flexible pipe section lifted y a counterbalanced pulley to build up a back pressure for periodic release

摘要

A system for automatically clearing sediment in underground drainage pipes is fitted into an inspection shaft (2) and comprises a flexible pipe (5, 6) inserted into the upstream connection into the shaft and a fitted with a short rigid pipe section (7) attached to a pulley system. The pulley raises the rigid pipe section via overhead pulleys (9) and a counterweight (11). This causes the fluid to back up behind the flexible section until sufficient back pressure overcomes the ballast weight and lets the pipe section drop down and release the trapped fluid in a pressure surge which flushes out sediment.