Most sluice gates (penstocks) are fabricated from various grades of stainless or corrosion-resistant steel, but certain sizes can also be manufactured from cast iron. Aluminium is usually used for handstops and stoplogs. Gates may be supplied with or without seals, depending on customer's requirements.
Operation of gates can be manual, electric, hydraulic or pneumatic.
Sluice gates (Penstocks) may be broadly divided into the following types :
Wall mounted gates, which are used to close off an opening in a wall, or the end of a pipe, and seal around the complete periphery of the opening. They can be either of the slide or roller type, and can be arranged to seal against on- or off-seating pressure, the former being where the pressure or flow tends to force the gate on to its frame and the latter where the gate tends to be forced off its frame. By fitting double music-note seals, a gate can be arranged to seal in both directions if necessary.
When a large gate has to be operated against a high unbalanced pressure, the force required to open it may be excessive, in which case rollers are fitted in order to reduce friction, and hence the operating effort.
Channel gates, used to control flow in open channels or canals, are of the 3-sided sealing type, having no seal along the top edge of the gate. They are normally screw operated, with handwheel or gearbox mounted on a bridge which forms part of the headframe. Wide gates may require twin lifting spindles.
Channel gates are usually mounted in slots cast into the sides and floor of the channel, but can also be wall-mounted if required.
Radial gates, which are often 3-sided sealing, are used in canals, or on dam walls, for flow control.
Weir gates, are either downward-opening, or bottom-hinged tilting type, and the flow over the top of the gate is controlled by adjusting its height. Depending on water level, and whether the gate must seal off the opening, weir gates may be either 3- or 4-sided sealing.
Twistlock gates. Quick-action hand-operated gates which can be locked in any partially open position simply by turning the T-handle.
Handstops and stoplogs. Simple hand-lift gates which do not normally have seals, as a certain amount of leakage is often permissible. However seals can be fitted if required.
Flow dividers. These are vertically pivoted swing gates used for diverting flow into either of two channels. Seals are optional.
Flap gates. Non-return gates, allowing flow in one direction only.
Telescopic bellmouths are used to draw off scum and surface fluids in tanks. Adjustment of the upper (sliding) tube is by means of an extended spindle.
Sludge drain valves. These are used in reservoirs and tanks to allow complete emptying. They are screw operated by means of an extended spindle, but can also be opened and closed hydraulically or pneumatically.
Hand-flushing valves. Lever operated valves for rapid draining of tanks, etc.
Ground water relief valves, for casting into floors of reservoirs, tanks, canals,etc., to prevent the build-up of excessive ground water pressure, which can cause lifting of the floor.