DAM & CANAL GATE

Radial Gate

A side view of a Radial gate resembles a slice of pie with the curved part of the piece facing the source or upper pool of water and the tip pointing toward the destination or lower pool. The curved face or skin plate of the gate takes the form of a wedge section of cylinder. The straight sides of the pie shape, the trunnion arms, extend back from each end of the cylinder section and meet at a trunnion which serves as a pivot point when the gate rotates. Pressure forces acting on a submerged body act perpendicular to the body’s surface. The design of the Radial gate results in every pressure force acting through the centre of the imaginary circle of which the gate is a section, so that all resulting pressure force acts through the pivot point of the gate, making construction and design easier. When a Radial gate is closed, water bears on the convex (upstream) side. When the gate is rotated, the rush of water passing under the gate helps to open and close the gate. The rounded face, long radial arms and trunnion bearings allow it to close with less effort than a flat gate. Radial gates are usually controlled from above with a chain/gearbox/electric motor assembly.
Radial gates are rotary gates consisting of cylindrical sections. They may rotate vertically or horizontally. Radial gates are a vertical design that rotates up to allow water to pass underneath. Low friction trunnion bearings, along with a face shape that balances hydrostatic forces, allow this design to close under its own weight as a safety feature.

Vertical Lift Gate

These are gates that moves within a vertical groove incised between two piers. The vertical lift gates used for controlling flow over the crest of a hydraulic structure are usually equipped with wheels. This type of gate is commonly used for barrages but is nowadays rarely used for dam spillways. Instead, the radial gates (discussed next) are used for dams. This is mostly due to the fact that in barrage spillways, the downstream tailwater is usually quite high during floods that may submerge the trunnion of a radial gate. The fixed-wheel vertical lift gates comprise of, in general, a structural steel frame consisting of end vertical girders with properly spaced horizontal girders between them. The spacing depends on the design water pressure and on dimensions of the gate. The frame is held a piece by secure welding or riveting. Skin plate protects the structural framework from damage due to ice and heavy debris, minimizes downpull, reduces corrosion and facilitates maintenance.

Sluice Gate

A sluice is a water channel controlled at its head by a gate. A mill race, leet, flume, penstock or lade is a sluice channelling water toward a water mill. The terms sluice, sluice gate, knife gate, and slide gate are used interchangeably in the water and wastewater control industry.A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway. Sluice gates commonly control water levels and flow rates in rivers and canals. They are also used in wastewater treatment plants and to recover minerals in mining operations, and in watermills. “Sluice gate” refers to a movable gate allowing water to flow under it. When a sluice is lowered, water may spill over the top, in which case the gate operates as a weir. Usually, a mechanism drives the sluice up or down. This may be a simple, hand-operated, chain pulled/lowered, worm drive or rack-and-pinion drive, or it may be electrically or hydraulically powered.

Stop Log Gate

Stop logs are a hydraulic engineering control element that are used in floodgates to adjust the water level or flow rate in a river, canal, or reservoir. Stop logs are sometimes confused with flash boards, as both elements are used in bulkhead or crest gates. Stop logs are typically long rectangular timber beams or boards that are placed on top of each other and dropped into pre-made slots inside a weir, gate, or channel. Present day, the process of adding and removing stop logs is not manual, but done with hydraulic stop log lifters and hoists. Since the height of the barrier can only be adjusted through the addition and removal of stop logs, finding a lighter and stronger material other than wood or concrete became a more desirable choice. Other materials, including steel and composites, can be used as stop logs as well. Stop logs are designed to cut off or stop flow through a conduit. Stop logs are modular in nature, giving the operator of a gated structure the ability to control the water level in a channel by adding or removing individual stop logs. A gate may make use of one or more logs. Each log is lowered horizontally into a space or bay between two grooved piers referred to as a stop log check. In larger gate structures, there will be multiple bays in which stop logs can be placed to better control the flow rate through the structure.

Trash Rack

The principal spillway for dams can be one of several designs. The proper operation of these spillways is an important part of maintaining the overall safety of the dam. Pipe and riser, drop inlet, and slant pipe spillways are susceptible to obstruction and damage by floating debris such as leaves, branches, and logs. One device used to ensure that these spillways operate correctly is a trashrack. A well-designed trashrack will stop large debris that could plug the conduit, but allow unrestricted passage of water and smaller debris. The larger the outlet conduit, the larger the trashrack opening should be. In the design of a trashrack, the openings should be sized so that they measure one-half the nominal dimension of the outlet conduit.

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