Channel gates are used in open channels for fluid flow control and therefore do not have a seal along the top edge of the gate. These gates are usually manufactured with an allowance of 100 mm to 200 mm above the maximum flow depth of the channel. Channel gates are normally mounted in slots within the side walls and floor of a channel, however the frames can be adapted to be bolted against a wall face if necessary.
Downward opening weir gates are similar to wall mounted gates, with the exception that the gate is used for the purpose of level control, being closed in the upward position and lowered to open. The fluid flows over the top of the gate and is controlled by adjusting the gate height. Depending on the water level, and if the application requires, the gate can be sealed off. As a standard, the gate will be sealed on all four sides or on three sides leaving the top open.
Flap gates are used in walls or on the end of pipes to prevent return of flow. The device consists of a frame with a gate or flap which is hinged at the top. To ensure closure against the frame the gate is double hung.
Hand stops are used in small open channels, a simple hand-lift operation where seals are optional, as a certain amount of leakage is often permissible. Normally the gate is manufactured from aluminum and frame stainless steel with HDPE guides.
For deep channels, the gate is manufactured in sections, known as a stop log system. The maximum width is generally 1000 mm.
Stop Logs are used to contain water in ponds, tanks, or channels, as well as in applications where installation or removal thereof is required infrequently. Stop logs are used in small open channels and simple hand-lift operations where seals are optional, as a certain amount of leakage is often permissible. Normally the stop log is manufactured from aluminum and frame stainless steel with HDPE guides.
Telescopic Bell-mouths are used extensively in wastewater purification works to draw off surface fluids and scum. A Bell-mouth consists of a lower outer tube which is
connected to a drain pipe, and an upper inner tube which slides up and down to vary the fluid level as required. Seals are fitted between the inner and outer tubes to prevent leakages. Telescoping valves are also used to regulate fluid levels, either by draining one tank into another or filling an adjacent tank with a higher water level. Operation is generally manual by means of hand wheel and spindle connected to the inner tube.
Tilting weir gates are used for wide openings where the vertical flow required is not more than approximately 500 mm. The gates are hinged at the bottom and the flow over the top is controlled by the adjustment of the angle or height of the gate. Depending on the water level, and if the application requires the gate to be sealed off, the gate can be sealed on three sides leaving the top open. For 2 m or wider twin spindle design will apply.
Wall mounted gates, also referred to as pen-stocks are used to close off an opening in a wall or the end of a pipe, and provide a complete seal around the periphery of the opening in the wall or pipe. Generally, seals are Ethylene Propylene Diene Monomer/ Music Note (EPDM) J seals which allow water pressure to force the seal against the seating surface of the frame. Where o-seating pressures occur, the seals are reversed. If both seating and o-seating pressure conditions are present, double seals are used. Ideally this kind of gate should use rising type spindle as the threaded section is out of the fluid.