Control valve with sand and leaf trap for drain in street or roadway has air access openings in sides of housing and float closing air valve when valve chamber is full of water

摘要

A perforated drain cover (2) lies flush with the road surface and covers the top of a shaft (1). A tray (4) with apertures (7) at the sides acts as a sand and leaf trap. Water flows from the sand and leaf trap onto a flat plate (5) with a central aperture (11) with an upstanding flange (12). Air flows through this aperture into a valve chamber (20). The water flows past a tube (18), with an air inlet (17) in each end, and a valve opening (19) in its center, closed by a float (22) on guides (21) when the chamber is full of water. A sieve (16) on the floor (14) of the chamber covers a small drain hole (15).