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Questions about VAG's Knife Gate Valves
Choose a question:
Can the ZETA knife gate valve be equipped with an E-actuator and non-rising stem?
Is the ZETA knife gate valve easy to install?
Can a knife gate valve be used in combination with drinking water?
Does the ZETA knife gate valve have flush ports?
Can the ZETA knife gate valve be used for regulation purposes in wastewater?
Can the ZETA knife gate valve be equipped with an E-actuator and non-rising stem?
Generally, the rising stem, combined with an output A on the actuator, is preferred because
- The coaxial stem means there is less operating torque on the actuator.
- The bearing of the actuator's spindle nut is ideal, which results in less wear and tear and a longer service life.
- Less stress increases the actuator's operation safety.
Is the ZETA knife gate valve easy to install?
The standard ZETA knife gate valve has a built-in scraper system that continuously cleans the door. This reduces the abrasion stress on the lateral seal in particular for valves that are installed horizontally or hanging. Due to excessive soiling, hanging valves generally require more maintenance than valves that are installed in a normal position. Due to its special technology, the ZETA valves have a considerably longer service life compared to competitor valves.
Can a knife gate valve be used in combination with drinking water?
The ZETA knife gate valve should not be used in combination with drinking water for the following reasons:
a) The gasket's wastewater-specific NBR elastomer composition has neither KTW nor W270 accreditation and may therefore not be used in combination with drinking water.
b) Because knife gate valves are used with wastewater, they must be lubricated around the door and the guide at every maintenance interval. The large amount of grease that is applied facilitates the deposit of coliform bacteria, which is why it is not recommended to use the valve in combination with drinking water.
c) When the valve is open, the door is pulled out of the housing and exposes the valve to the environment. When the valve is shut, impurities can enter the valve and pollute the drinking water.
Does the ZETA knife gate valve have flush ports?
Yes, the door's lateral guide rails are exposed at the ends. This means that impurities around the guide are easily picked up by the flow and flushed out. In contrast to the knife gate valve with the old WEY principle (for example, Sistag VNA or MFA, Burbach) and rectangular door, the ZETA valve's half-round gate has a smooth and easy lower passageway and no hazardous grooves.
Can the ZETA knife gate valve be used for regulation purposes in wastewater?
Technically, this does not make sense because the control curve of standard knife gate valves only has a noticeable effect on the flow rate when the valve is between 80 and 95 per cent closed. The valve can only be regulated in this narrow range. To increase the range toward 100 per cent, so-called restrictors have to be used. It is, however, imperative that the shape of the restrictors in the lower passageway does not prevent sediment being flushed.