Depending on its nominal diameter, the VAG ZETA^® Knife Gate Valve can be used for operating pressures of up to 10bar. Due to design improvements of nominal diameters DN1000 to DN1400, valves of this size can now be used for an operating pressure of 4bar. The main field of application is the use in media containing solids, such as wastewater, sludge and storm water. The parts of the body are made of premium-quality cast iron grade EN-JL- 1040 in the VAG-Group’s own foundry. In order to provide the required strength, nominal diameters DN1000 to DN1400 are made of ductile iron grade EN-GJS-400-15 (GGG-40). The knife is made of stainless steel grade A2 as a standard or also of grade A4 upon special request. The seals are produced from NBR, a material suitable for use in wastewater. A premium- quality epoxy coating with a coating thickness of 250μm is applied to protect the parts of the body against corrosion.
Designed as a wafer-type and endof- line valve, the knife gate valve can be installed universally at full differential pressure even without a counter-flange. Thanks to its fully flanged design, the leak-tightness of the valve is ensured in both flow directions. When the valve is closed, the pipeline can be dismantled on one side even under operating pressure. The advantages stated result in the reduction of potential installation errors during assembly at the construction site and thus considerably increase safety of assembly: The VAG ZETA^® Knife Gate Valve is the universally applicable standard valve for the user and features clear advantages compared to conventional valves available in the market. The complete leak-tightness of the valve in both flow directions provides high reliability of operation. This is made possible by its integrated scraper system which ensures permanent cleaning of the knife. The closed and compact body construction made of stainless sheet steel also offers a high level of protection against personal injuries that might be caused by the moving components. At the same time, the construction of the body serves as an effective guard and protection of the knife and external actuating parts against adverse environmental impacts such as dust, dirt, aggressive atmospheres or intensive solar radiation.
Valves with nominal diameters greater than DN600 are equipped with elastic PTFE slide bearings which ensure optimum guiding of the knife. This unique ZETA sliding system prevents the knife from coming into contact with the body, thus reducing operating torques, increasing the useful life and improving the reliability of the valve. One of the main tasks of the designers of the ZETA^® Knife Gate Valve was to ensure high maintenance-friendliness for its users. This could be realised by the maintenance-friendly sealing concept featuring a pressure-supported sealing system of the knife. It is additionally supported by the smooth and unrestricted flow passage which eliminates the risk of incrustations. As a result, operating torques are consistently minimal, providing for minimal wear and a long service life at the same time. Whenever necessary, the lateral seal of all nominal diameters can be replaced without the need of dismantling the valve from the pipeline.
The special feature of the ZETA^® Knife Gate Valve is that it can be retrofitted at any time with all available actuator varieties and without dismantling it from the pipeline. Its compact body design also allows for the easy and universal installation of limit sensors on the valve.