Abstract: A coupling is provided preferably for a vortex valve for use on an outlet pipe in a sewerage system. The coupling comprises an outer component for insertion into a bore of a pipe, and an inner component which is inserted into the outer component, ramp means being provided between the two components, whereby the outer component is expanded to seal against the bore when the inner component is inserted into the outer component so as to engage the second ramp portion. The ramp means comprise first and second portions of different inclinations. The vortex valve has a circumferential inlet which is adjustable.

Abstract: A hydrodynamic treatment device comprises a vessel (2) within which is disposed an inner partition (24). The inner partition (24) divides the interior of the vessel (2) into outer and inner regions (22, 28). Flow enters the vessel (2) through a tangentially oriented inlet (14) and establishes a complex circulating flow within the vessel (2). Settleable solids migrate to the bottom of the vessel (2) and are deposited in a sump (20) through a solids outlet opening (18). Flow enters the inner region (28) through apertures (34) in the inner partition (24), and is discharged through an outlet duct (8). The inner region (28) is closed at its lower end by a frusto-conical, downwardly diverging lower wall (30) which projects outwardly from a central cylindrical wall (26).

Abstract: A separator comprises a gully chamber 2 having inlet and outlet ducts 10, 12. Inlet and outlet housings 20, 22 are disposed within the separator and are connected by a bypass duct 24 which extends around the wall of the chamber 2. Flow enters the chamber through an inlet which is oriented to create a circulating flow. Flow exits from the chamber through an outlet opening provided in the outlet housing 22. The outlet opening is oriented in the direction of the circulating flow so that liquid has to reverse from that flow to pass through the outlet opening. The inlet and outlet housings 20, 22 are made from identical mouldings in which appropriate openings are formed. The bypass duct can be cut to length to position the inlet and outlet housings 20, 22 opposite existing inlet and outlet ducts 10, 12.

Abstract: A coupling is provided preferably for a vortex valve for use on an outlet pipe in a sewerage system. The coupling comprises an outer component for insertion into a bore of a pipe (62), and an inner component (26) which is inserted into the outer component, ramp means being provided between the two components, whereby the outer component is expanded to seal against the bore when the inner component (26) is inserted into the outer component so as to engage the second ramp portion. The ramp means comprise first and second portions (28, 30) of different inclinations. The vortex valve has a circumferential inlet (11) which is adjustable.

Abstract: An overflow chamber (2) is provided for use in a combined sewer overflow. An inlet (12) and an outlet (14) open into the chamber (2) below a screen (20), and an overflow outlet (15) opens into the chamber above the screen. Baffles (26) are provided underneath the screen (20) across the general flow of storm water. In storm conditions, the storm water in the chamber (2) will reach the level of the screen (20), which traps aesthetically offensive material and gross solids, leaving the water to flow through the screen (20) to the overflow outlet (15). The baffles (26) circulate the storm water, and this dislodges material accumulated on the underside of the screen (20) and so helps to prevent blinding of the screen (20) in storm conditions.