Valves for dams, reservoirs and hydropower
The AVK Group provides an extensive portfolio of high-quality discharge control valves and guard valves produced within our own facilities, together with a broad selection of additional valve types sourced from our brands and carefully chosen partners.
AVK is recognised worldwide as a leading manufacturer of valves for the water sector. Several of our companies specialise in the advanced valves and gates required for dams, reservoirs and hydropower installations. Orbinox has spent more than 40 years delivering customised solutions to diverse projects around the world. Glenfield brings over a hundred years of experience to this field, with early references dating back to 1913, and its robust designs are now produced at our modern large valve facility in China. AC.MO contributes an extensive range of needle valves and AVK’s wide assortment of water supply products completes the offering.
Below you will find a brief overview of our own manufactured products along with links to our product finder, where datasheets for each item are available.
- Discharge control valves: fixed cone and submerged discharge valves, and needle valves
- Radial gates
- Roller gates
- Stop logs and gates
- Penstocks
- Guard valves: butterfly valves, knife gate valves, bonneted gate valves and gate valves
- Check valves: tilting disc check valves and recoil check valves
- Regulating valves: needle valves and ball float valves
- Air valves
- Dismantling joints
Please also find links to our brochure, animations and case stories at the bottom of this page.
Discharge control valves
Discharge control valves are engineered to manage the release of water from dams, reservoirs and hydro by-pass systems while ensuring the safe dissipation of the substantial kinetic energy present in fast-moving flows.
Fixed cone (free discharge) valves create a hollow jet of water discharged directly into the air. Submerged discharge valves release a controlled jet beneath the water surface into a stilling basin or sump. Needle valves are most often installed as inline control valves, though they can also be configured for atmospheric discharge. All three valve types can regulate or close bottom and mid-level outlets in dams and reservoirs and are commonly used within turbine by-pass arrangements in hydropower schemes.
These valve designs are known for their reliability, efficiency and long operational life, making them essential components in dams, reservoirs and other critical water installations worldwide.
Fixed cone (free) discharge valves
Fixed cone valves are lightweight, straightforward discharge control valves that produce a hollow cone-shaped jet in the form of a spray or fan. Because of this jet pattern they are often referred to as hollow jet valves or jet disperser valves. They are also widely known as sleeve valves, as well as Howell–Bunger valves, named after Howell and Bunger who developed an early fixed cone design in the 1930s.
Since these valves discharge directly into the atmosphere, any cavitation takes place in the surrounding air rather than inside the valve, preventing internal damage. The kinetic energy of the water is dissipated naturally against atmospheric pressure before falling like heavy rainfall or being guided, via a hood, as a directed jet into a downstream stilling basin. Fixed cone valves provide linear control and can operate reliably at any opening above roughly 10 per cent, which makes them well suited for regulation duties and environmental flow releases. They also tolerate significantly higher velocities and flow rates (up to around 25 m/s) compared with many alternative control valve designs. As a result, they can often be selected in smaller sizes for a given duty, do not require installation inside a valve chamber and remain straightforward to operate and maintain.
The ORBINOX fabricated fixed cone discharge valve type CH can be tailored to meet the service requirements of individual installations. Units are available up to DN3000, with designs capable of handling heads of up to 400 mWc, manufactured in carbon steel or a choice of stainless steel grades. Manual, electric or hydraulic actuation options are available. An animation illustrating the operating principle can be found at the bottom of this page.
→ Series 1425 fabricated fixed cone discharge valves, type CH
The AVK series 857 fixed cone discharge valves, based on the Glenfield design, feature a robust one-piece ductile iron body that provides excellent structural rigidity. The sleeve is manufactured from acid-resistant stainless steel and combined with epoxy coated ductile iron components to ensure strong protection against corrosion.
This PN16 range is offered in sizes from DN200 to DN2200 and can be supplied with a manual gearbox, electric actuation or hydraulic actuation depending on the installation requirements.
→ Series 857 cast fixed cone discharge valves
Submerged discharge valves
AVK submerged discharge valves, developed from the Glenfield design, offer effective discharge control within a notably compact layout. Their design ensures quieter operation, safer energy dissipation and a more environmentally considerate release of flow. The valves are produced in ductile iron and feature a bronze‑ported, epoxy coated body paired with stainless steel internal components to provide strong corrosion resistance. They are supplied in sizes DN200 to DN1600 for PN16 duties and DN600 to DN1000 for PN25 applications, with options for electric actuation or manual gearbox operation.
→ Series 856 submerged discharge valves
Needle valves (also known as ring needle valves and plunger valves)
AC.MO needle valves are engineered for inline throttling duties, providing reliable control of pressure and flow under moderate flow conditions and high differential pressures. They may also be installed as discharge control valves venting to atmosphere, although they are generally limited to velocities of around 10 m/s and do not dissipate energy. Instead, they produce a concentrated jet, making them well suited for conveying flow along a pipeline or conduit. Needle valves are particularly effective for steady inline regulation from intermediate outlets feeding fish passes, irrigation networks or pipelines supplying water treatment facilities and similar systems. The range extends up to DN2500, with smaller diameters available in ratings up to PN40. Valves up to DN150 are supplied in stainless steel as standard, while the larger units are cast in ductile iron with a fusion bonded epoxy coating for long-term protection.
→ Series 872 needle valves
Radial gates
Radial gates are commonly installed in channels and dam spillways to control upstream water levels or to function as regulating and discharge units for bottom outlets. A radial gate is formed from a curved, sector‑shaped panel constructed as a welded assembly. Sealing is achieved through elastomer profiles fixed to the panel, which press against embedded seating surfaces within the concrete structure. Only a small movement is required to raise or lower the gate, which keeps lifting forces low. Key benefits include quick operation, high discharge capability and reliable, uncomplicated handling.
The ORBINOX type CT radial gates are manufactured in carbon steel and engineered to suit the operational requirements of each installation. Gates used in channels or spillways are sealed on three sides (both sides and the bottom) and are designed to accommodate overspills where necessary, with structural capacity for water loads equal to the maximum gate height plus the specified overspill. Gates intended for deepwater outlets in dams are sealed on all four sides and designed to withstand water heads of up to 100 mWc.
→ Series 1428 radial gates, type CT
Roller gates
Roller gates are typically installed where large openings need to be closed off and where high water loads must be managed. They are frequently used on intake towers, dam inlet structures and as protective elements at hydropower stations, where they may also serve as regulating devices for the turbine’s connection to the grid. The gate is built as a robust, reinforced fabricated structure and is guided by side rollers that help minimise operating forces during movement. ORBINOX roller gates are produced in carbon steel or stainless steel and are tailored to the specific duty conditions of each project. They are designed to withstand water heads of up to 100 mWc and can be supplied with either hydraulic or electric actuation.
→ Series 1429 roller gates, type MV
Stop logs and gates
Stop logs are modular, removable elements used to manage and isolate water flows in hydraulic structures such as dams, reservoirs, spillways and hydroelectric facilities. Usually manufactured from aluminium or steel, the logs are stacked vertically inside guide slots that are cast into concrete piers or walls. Their main purpose is to provide temporary closure or diversion of water so that maintenance, inspection or operational work can be carried out without relying on permanent gates or valves.
ORBINOX stop logs are intended for open channel installations within treatment plants, irrigation networks, hydraulic works and hydro-electric power schemes. Each slide is created by positioning several individual logs on top of one another within the frame. By adding or removing these elements, operators can adjust or completely block the flow in a channel. A sealing arrangement is fitted to the sides and the underside of each log, ensuring a watertight closure. Although the frame is most often cast into concrete, alternative configurations can be supplied for wall mounting or for installation against existing channel structures. The ORBINOX SL series is manufactured from stainless steel, while the SA series is produced in aluminium. Stop gates (type AG) can also be provided on request.
→ Series 772/83 stop logs, type SL
Penstocks
Penstocks are used to isolate and regulate flow in pipelines, channels and reservoirs. They are widely applied in water and wastewater treatment facilities and are equally common in flood management and irrigation schemes, where they provide a dependable and economical means of flow control and shut‑off.
ORBINOX penstocks are manufactured from steel or stainless steel and are engineered for long service life in demanding environments. They feature a robust construction, low leakage performance and a modular design that allows straightforward customisation to suit project requirements. Their self‑adjusting sealing system ensures smooth operation, and they can be equipped with manual, electric or hydraulic actuation. Wall‑mounted penstocks are available in square or rectangular formats, sealed on all four sides, and offer bi‑directional capability up to 1200 x 1200 mm. The range also includes both round and rectangular swing‑flap gate penstocks.
→ Series 772/6X wall penstocks, type MU
Guard valves
Guard valves are high‑velocity emergency closure and maintenance valves installed upstream of discharge control valves. They act as primary isolation units, designed to stop water flow in large‑diameter pipelines, penstocks and intake structures either during emergency situations to ensure operational safety or to allow safe maintenance of downstream equipment.Butterfly valves
Butterfly valves are widely applied in dams, reservoirs and hydropower facilities. Their compact build and quarter‑turn operation make them cost‑effective solutions, particularly where space is limited and rapid shut‑off is required. We supply a broad selection of fabricated and cast double‑eccentric butterfly valves designed to meet the demands of high‑pressure, high‑velocity and large‑diameter duties in water infrastructure.
The ORBINOX type MB double‑eccentric butterfly valves are engineered for the specific operating conditions of each installation and are suitable for liquid velocities of up to 10 m/s. They are typically used as protection valves for penstocks and as main inlet valves at hydropower plants, as well as guard or emergency shut‑off valves positioned upstream of discharge control valves in dam and reservoir outlets. Units can be manufactured up to DN3500 in a wide range of material combinations to meet project requirements and can be supplied with hydraulic, electric or manual actuation.
→ Series 1427 fabricated double eccentric butterfly valves, type MB
AVK double eccentric butterfly valves are designed for shut-off in water applications and are available up to DN3200 and for pressure ratings up to PN25. The slightly tilted disc, optimized seal design, unique shaft pin design and the corrosion protected shaft end zones are all features that exceed the market standards.
→ Series 756 cast double eccentric butterfly valves
Knife gate valves for high pressure/high velocity closure
High pressure knife gate valves, also known as bonneted slide gates, are ideal for large-diameter pipelines where high flow volumes and velocities must be precisely controlled. They are especially effective for media with suspended solids, making them well-suited for dams, reservoirs, and similar applications. The straight-through design ensures minimal pressure drop, while their compact construction offers low operating torque and easy installation - ideal for large-scale infrastructure projects.
ORBINOX fabricated knife gate valves type WS are available up to DN4000. They feature a machined gate with a sharpened edge for full tightness under demanding flow conditions. Designs are tailored to specific pressure, temperature, and velocity requirements. Various configurations are available for materials, sealing systems, flange standards, actuators, and coatings to ensure optimal performance and durability.
→ Series 1432 fabricated knife gate valves, type WS
ORBINOX cast knife gate valves type CW are available in DN80-1000 (bigger sizes on request), and up to PN100 depending on size. They are uni-directional with features and configurations like the fabricated versions.
→ Series 1431 cast knife gate valves, type CW
Bonneted gate valves
A common high dam bottom outlet configuration utilises two bonneted gates installed close together in series. The downstream valve is the working/service valve, with the upstream safety/maintenance valve used only for maintaining the downstream valve. Bonneted gate valves are designed with a rectangular port geometry with a flat metal sealing surface at the bottom. The gate is fully supported all the way down enabling it to close safely into extreme velocities, and to ensure that any debris is flushed through the valve without becoming stuck and preventing its closure. Bonneted gate valves are generally located at bottom or mid-bottom water outlet conduits, with their bodies and bonnets up to their top flange embedded in concrete for extra strength. Due to their size and weight of the gate, they are usually hydraulically operated.
ORBINOX bonneted gate valves are designed for the specific service conditions of each application and are available in sizes up to 2500 x 3500 mm supporting water loads of up to 200 mWc and speeds more than 35 m/s. They are made of carbon steel or stainless steel with bronze rims and moving parts of stainless steel and are normally actuated with a hydraulic actuator due the high stress required.
→ Series 1426 bonneted gate valves, type BU
Gate valves (wedge design)
Gate valves play a critical role in water infrastructure such as dams, reservoirs and hydropower plants by ensuring reliable shut-off of large water volumes under high pressure. Designed for infrequent on-off operation, they offer minimal flow resistance when fully open due to the full bore, making them ideal for isolation duties.AVK metal seated gate valves (Glenfield design) are available up to up to DN2200 in PN10 & 16 and DN1200 in PN25 & 40 and designed for reliable high-strength performance in large diameter water pipelines. Its metal-to-metal sealing makes it ideal for raw water applications. A special ‘Reservoir Spec’ version of the S54 (S54-41) has been developed for use in dams, reservoir & and hydropower applications, where the ability to close reliably into higher velocity flows of up to 9 mps is critical.
→ Series 54 reservoir specification metal seated gate valves (download brochure)
AVK resilient seated gate valves are made of ductile iron with GSK approved epoxy coating and a wedge fully encapsulated in rubber offering 100% tightness and corrosion protection, ideal for water supply and reservoir systems up to DN1200, and as bypass valves.
→ Series 06 resilient seated gate valves
Check valves
Check valves are essential in protecting water infrastructure from reverse flow, pressure surges and pump damage during shutdowns. The robust design, low maintenance needs and available configurations make our check valves ideal for high-capacity installations.
Tilting disc check valves
ORBINOX tilting disc check valves type RA are double eccentric with wafer or flange connection and cast or fabricated carbon /stainless steel body, available up to DN1600 for applications up to PN16, and for horizontal and vertical installations. They are designed with an external counterweight assembly to help initiate closing when normal flow stops and before there is reverse flow. A hydraulic damping system controls closing velocity and prevents any water hammer in the pipelines. The check valves are ideal for rapid, non-slamming protection against reverse flow in high-pressure dam and hydropower systems.
→ Series 1410 tilting disc check valves, type RA
Recoil check valves
AVK multi-door recoil check valves are available up to DN1600, and for pressure ratings up to PN25. They are cast in ductile iron with gunmetal seat and are designed for surge-critical applications, ideal for protecting pumps and pipelines in dams, reservoirs, and hydropower facilities.
→ Series 641 multi-door recoil check valves
Regulating valves
In complex water systems like dams and hydropower plants, regulating valves and air valves support safe and efficient operation of the system. For high-pressure and/or critical flow regulation, needle valves offer accurate throttling by virtue of their near linear flow characteristic, making them ideal for turbine bypasses and bottom outlets.
Needle valves (plunger valves)
AC.MO needle valves, available up to DN1600 and PN40 as standard, are designed for throttling and control of pressure and flow at high flow rates and high differential pressures. The focus is on durability and reliability with the sturdy valve housing made of stainless steel up to DN150 and ductile iron coated with fusion bonded epoxy in larger sizes. They are ideal for turbine bypass and bottom outlet duties in dams and hydropower systems.
→ Series 872 needle valves
Ball float valves
AVK ball float valves are designed to be fitted in the top of a tank or reservoir to automatically control the rate of filling and shut off completely when a predetermined level is reached, and are ideal for maintaining safe water levels in smaller reservoir installations. The balanced equilibrium design makes sure that operation is smooth and reliable. They are cast in ductile iron with lever and float of ABS or stainless steel and available in DN50-300.
→ Series 854 ball float valves
Air valves
Air valves protect pipelines by automatically releasing trapped air during filling and allowing sufficient air into the pipeline to prevent a vacuum forming behind a disc, needle/plunger or gate closing into a high velocity flow, or during pipeline drainage. If a vacuum is allowed to form, then damaging downstream cavitation or even pipe collapse can occur.
AVK double orifice cluster arrangement air valves with VNR function are designed for reliable air release and vacuum prevention in water pipelines up to PN16. They allow air to enter the pipeline freely on separation but controls the expulsion as the column rejoins. This creates an air buffer that effectively reduces the impact velocity and the surge potential of the system. The second orifice automatically discharges accumulated air during normal working conditions. They are cast in ductile iron with all other components in polymer material or stainless steel.
→ Series 851 air valves
Dismantling joints
Dismantling joints facilitate easy installation and removal of flanged pipes, valves, pumps, and other equipment. They allow axial adjustment during assembly and disassembly, thanks to their telescopic design. We offer two main configurations, see more details:
- Central flange design with tie rods ensuring high strength and tight sealing, available in various configurations and up to DN2600 and PN25
- Compact two-flange space-saving design with fewer tie rods, available in mild steel up to DN1600 and PN16
