VAG GmbH

As early as in the 1930s, the performance of water supply systems and hydropower stations was increased in a way that the requirements in terms of pipeline diameters and pipeline lengths as well as operating pressures and flow velocities increased as well. The shut-off devices used at that time, mostly wedge gate valves, had to be optimised and adapted to the new demands. Wider sealing rings were used, wedge guides were reworked or also extended, but in the end the conventional gate valve was not a suitable control valve.   

At that time, the annular slide valve constituted a special type within the valve business. However, the round cross-section of the annular slide valve was transformed into an annular cross-section by an internal body, which turned into a round cross-section again at the outlet of the valve. This was how the annular slide valve got its name. In the course of the years, the annular slide valve evolved into the needle valve and afterwards to annular piston valve and plunger valve.

Plunger valves are special control valves, designed specifically for control tasks in all kind of water supply systems. Unlike gate valves and butterfly valves, which are mainly used as shut-off valves only in pipeline networks, plunger valves meet the special requirements of control functions. Plunger valves are mainly used where volumetric flow rates need to be precisely apportioned or where water pressures have to be accurately controlled or reduced.

The VAG RIKO Plunger Valve is a straightway control valve, i.e. it has an annular flow cross-section in any position. Inside the body, the plunger (also referred to as piston) is moved axially in flow direction by a crank gear towards the sealing seat of the valve. VAG RIKO Plunger Valves are control and regulating devices which generate different pressure losses in pipeline systems by way of continuous narrowing towards the seat to change the flow rate in dependence of the regulating distance. Depending on the application, the nominal diameter of the valve has to be large enough to ensure that at the lowest pressure difference the highest required flow rate is achieved and/or that maximum differences in pressure are reduced without causing any cavitation. Additionally, any damage to the downstream pipeline system or structure by vibration or cavitation must be prevented over the entire regulating distance.

The first VAG Plunger Valve was developed in 1932 in Mannheim/ Germany. Meanwhile VAG has evolved the VAG RIKO Plunger Valve, proven for decades, to make it suitable for control tasks in water supply systems. Today’s VAG RIKO Plunger Valve is available in almost all nominal diameters between 6in up to 90in and in pressure ratings ranging from class 150 to 580 PSI. Meanwhile a great number of plunger valves are in use worldwide – even valves of sizes 24in and 32in with a nominal pressure of 1,500 PSI. In all sizes and pressure ratings, the compact body is made of premium-quality ductile iron ASTM A536 60-40-18 or cast steel ATSM A216 WCB. For special applications VAG can provide the RIKO Plunger Valve in FULLY STAINLESS STEEL version as well. For all nominal diameters up to and including 90in, the piston is guided by bronze-welded longitudinal guides. This ensures optimal longitudinal guiding and thus the backlash-free sliding of the plunger with very low operation torques at the same time.

Due to its linear control characteristic, the VAG RIKO Plunger Valve ensures excellent cavitation behaviour and minimum pressure loss in fully opened position at the same time. Its outlet type is variable and, in the form of a kit, allows the change of the valve characteristic. This is an essential advantage as the valve can be adapted to different operation conditions even after its delivery. The cylinders divide the flow into separate water jets which meet again on the discharge side downstream of the plunger in the centre line of the pipe and dissipate the energy of the water without the risk of cavitation.

Depending on the application and the operation specifications, different types of outlets such as standard seat ring, orifice cylinder or slotted cylinder as well as various special customized trims ae available to prevent cavitation.

The VAG RIKO® Plunger Valve is NSF 61-certified for contact with drinking water.

Howell-Bunger Discharge Valves were first developed and introduced for dam outlet works service in the early 1930’s by Mr. C. H. Howell and Mr. Howard P. Bunger, with the United States Bureau of Reclamation. VAG acquired the product line from Allis-Chalmers in 1990, has continued to develop the design for optimal performance and owns the trademark for Howell-Bunger Valves.

VAG KSSplus Howell-Bunger Discharge Valves provide controlled discharge of water while protecting the downstream environment. The valve breaks up the water into a large, hollow, expanding spray and can be used in most
situations, including submerged applications. An additional steel stationary hood concentrates the discharge spray
into a “jet” for a more controlled flow stream. They are ideally suited for low level outlet works for power projects,
turbine bypass, gate surge relief, flood control systems, irrigation facilities, and draining reservoirs or ponds.

Proven Performance
VAG KSSplus Howell-Bunger® Discharge Valves are proven performers with over 650 installations globally in the past 80 years.

Smooth, Vibration Free Operation
Cylindrical sleeve with adjustable sliding caps provide efficient, free-discharge operation for high and low heads, operating through the entire stroke range without vibration or cavitation.

Drip-Tight Sealing
Downstream primary metallic sealing, secondary flexible sealing, and upstream quad o-ring provide optimal sealing 
performance and prevent twist, roll, and point loading.

Easy to Operate and Maintain
Long guides with adjustable sliding caps provide smooth, non-binding movement. Sealing can be replaced without 
dismantling the valve from the line
 

Valve Operation
VAG KSSplus Howell-Bunger® Discharge Valves are typically operated by a manual, electric, or hydraulic actuator mounted above a double bevel gearbox. The gearbox transmits torque to the twin power screws (one on each side of valve) which in turn engage bronze thrust nuts to open (retract) or close (extend) the cylinder gate. 

In open positions, flow is directed outward around the deflector cone at a 45° angle (approximate) in a wide spray pattern into the atmosphere, dissipating remaining hydraulic energy without erosion of the surrounding area. By using a stationary hood, the wide spray pattern is redirected inside the hood to create a jet-like stream. This is often helpful where the wide spray pattern of Howell-Bunger Valves is objectionable or subject to freezing or ice build-up. Depending on the application, a venting device may be required for cavitation-free operation.

Howell-Bunger Valves are manufactured from fabricated steel or if required completely in STAINLESS STEEL. Meanwhile VAG can proof couple of Stainless steel installations in the US.  

Since 1935, over 650 VAG Howell-Bunger Discharge Valve have been installed in applications ranging from 8” valve with 1400’ of head, to a 112” valve with 209’ of head. In settings throughout the world, Howell-Bunger Valves have been the valve of choice wherever the control of water flow under free discharge is needed.

 

The double-offset VAG EKN^® Butterfly Valve is the universally applicable standard valve that provides significant benefits to 
endusers in comparison to conventional single-offset butterfly valves available on the market. The double O-ring sealing of the shaft bearings, the closed bearing lugs in the shaft bearing area assure a dry-shaft design. The high-alloy, chromium weld-overlay seat on the body ensures uninterrupted and reliable operation, even over decades. The EKN Butterfly Valve design ensures versatile installation of the valve even at full differential pressure. The pressure-supported profiled sealing ring on the disk
guarantees leak tightness in both flow directions. When the valve is closed, the pipeline can be disassembled on one side and the sealing ring can be replaced without dismantling the valve from the pipeline. The advantages mentioned result in a reduction of potential installation errors during assembly at the construction site, thus greatly enhancing assembly reliability. 

The platform of the VAG EKN^® Butterfly Valve is available in different versions:

- Standard version for waterworks application acc. to AWWA standards with high quality ductile iron body and disk design
- Customized version for Dam and Hydropower application for high velocities up to 65 fps
- Customized version with VAG HYsec hydraulic actuator and counter-weight for emergency closure demands
- Customized version for Industry applications with internal rubber lining of body and disk
- Customized version with locking devices on the body to secure the disk in closed position for maintanance purpose
- Customized version with fabricated body and but welds ends instead of flanges, to be welded into steel pipelines

The customized version with VAG HYsec hydraulic brake-and-lift unit is suitable for emergency closure against full flow. Dry-bearing design assures for long lifetime, a lattice type flow through disk provides low flow resistance, suitable for very high flow velocities up to 65 fps. The factory-assembled unit consisting of valve and actuator can be used as pipe-burst safety device in bottom outlets of dams or as turbine inlet valves/ turbine shut-off valves as well as in bypass lines. Available from 6” up to 168” in fabricated body and disk design made of carbon steel or stainless steel.

The main fields of application of the VAG EKN Butterfly Valve include water extraction, water distribution, water treatment, drinking water supply, cooling water in industrial and power plants, Dam and Hydropower applications where the EKN Butterfly Valves have stood the test for decades.