VAG Operating and Maintenance Instructions • 3
For knife gate valves with premounted electrical multiturn
actuators, the storage instructions issued by the respective
actuator manufacturer must also be observed!
3 Product features
3.1 Features and function description
The VAG ZETA®Knife Gate Valve is a gate valve in full-flange de-
sign and can thus be applied either as wafer type in-between two
flanges or for pipeline-end installation without additional counter
flange and at full operating pressure. Due to its bi-direc- tional
sealing arrangement, any installation position is possible. The kni-
fe slides in a U-profiled gasket made of elastomer bet- ween the
two body parts. Sealing in flow direction is pressure-supported
and soft sealing.
The sealing of the knife at the outlet of the body is realised by a
defined and elastically prestressed lateral seal. This seal can be
readjusted during operation and be easily replaced without dis-
mantling the valve from the pipeline.
Warning!! Ensure the pipeline is depressurised before
performing any replacement works.
In case of suspended installation of the valve, knife must be
field-secured against falling out.
The lateral seal is factory-adjusted (pretensioned) with a sealing
force equal to the nominal pressure (PN). In order to reduce the
operating forces and the wear of the lateral seal, this pretension
may later be adjusted to the actual operating pressure. To do this,
loosen the screws holding the thrust piece accordingly.
The electric multiturn actuator is directly mounted on the valve.
The connection dimensions between the multiturn actuator and
the valve are according to DIN ISO 5210.
The shut-off of the multiturn actuator in closing direction is
factory-adjusted in dependence of the torque. In opening
direction, the actuator is shut off in dependence of the po-
sition. The respective final positions „OPEN“ and „CLOSE“
are signalled by a limit switch!! This factory adjustment
must be observed for the planning and configuration of the
electronic control!
The factory-adjusted torque-controlled shut-off of the multiturn
actuator in „closed“ position guarantees the defined pressing of
the bore seal and prevents premature leaking of the valve. This
adjustment ensures that the knife exerts a constant closing force
on the bore seal which can neither be affected by the com- pres-
sion set of the seal nor by wear and tear of the stem nut or any
other positional changes.
The position-controlled shut-off of the multiturn actuator in
„closed“ position is also available upon the customer‘s express
request. However, we expressly point out that we assume no lia-
bility for the failures that usually result from this shut-off method,
such as leaks due to the compression set of the bore seal and the
required readjustment of the limit position.
For the user‘s information, a clearly visible label has been atta-
ched to the cover of the switch mechanism of the electric actu-
ator (see Fig. 1), bearing the adjustment information, adjustment
torques etc.. The screws of the switch mechanism cover are fac-
tory-sealed with sealing wax. Breaking this seal by unauthorised
opening will result in the loss of warranty.
1 General
1.1 Safety
These operation and maintenance instructions must be observed
and applied along with the general „VAG Installation and Ope-
ration Instructions for Valves“. Arbitrary alterations of this pro-
duct or parts supplied are not allo- wed. VAG will not assume
any liability for consequential damage due to non-compliance
with these instructions. When using this valve, the generally
acknowledged rules of technology have to be observed (e.g.
DIN standards, DVGW data sheets, VDI directives, etc.). The in-
stallation must only be carried out by qualified technical staff.
For further technical information such as dimensions, materials or
range of application, please refer to document KAT 2410-A.
1.2 Proper use
The VAG ZETA®Knife Gate Valve is a valve for installation into the
pipeline, either as wafer type, fitted between flanges, or for end-
of-line applications.
In its standard version, this valve is designed for the shut-off of
pressurised pipelines. For technical data concerning the operating
limits (e.g. operating pressure, medium or temperature) please re-
fer to the product-related documentation KAT 2410-A. Alternative
operating conditions and applications require the manufacturer‘s
written approval.
The valve has been designed for operation in liquids. If it
is operated temporarily in dry media, increased operating
forces as well as increased wear of the lateral seal and the
U-profile seal are to be expected. Permanent dry operation
is impermissible for technical reasons!
2 Transport and Storage
2.1 Transport
The transportation of the valve to the installation site must be un-
dertaken in suitable and stable packing corresponding to the val-
ve size. The packing must guarantee protection against weat- her
influences and damage from external forces.
In some cases, e.g. overseas transport, with specific climatic in-
fluences, the valves must be protected by wrapping them in plas-
tic film and adding a desiccant.
In case of premounted drives or actuators, these have to be stored
in a safe way which prevents the connection areas from being ex-
posed to transverse loads. The factory-applied corrosion protec-
tion coating must be especially well protected at all times. When
valves with pre-mounted electrical actuators are moved, the lifting
equipment must not be attached to the multiturn actuator and not
to the handwheel!
2.2 Storage
Store the ZETA®Knife Gate Valve with the knife in the closed po-
sition. Protect the elastomeric parts (gaskets) against direct sun-
light; failure to do this may deteriorate the seals and thus affect
proper and long-term function.
Store the valve in a dry and well-aerated location. Protect the val-
ve from direct radiator heat. Protect any assembly units impor-
tant for the function such as the stem, stem nut, gaskets or knife
against dust and other dirt by adequate covering.
Connect the multiturn actuator to the mains supply immediately
after assembly so that its heating can prevent the formation of
condensation water!
