Drainage pipe backwash valve seal involves float valve and counterweight on common shaft so seal closes automatically by counterweight without external force.

摘要

In a backwash situation the rising float (7) and counterweight (9) automatically close the open seal (5) without external force, using the weight for sufficient closing power. The float, counterweight and seal combinations lie on a common shaft (3) clear of the valve housing (1). Additional components include the sealing sleeve (6) and runoff pipe (8).