The space between the flanges should be wide enough to pre-
vent damage to the coating of the flange gasket frames during
installation.
In case of works around the valve causing dirt (e.g. painting,
masonry or working with concrete), the valve must be protec-
ted by adequate covering.
For assembly in drinking water pipelines, suitable sealing mate-
rials, lubricants and process materials must be used which are
approved for use in drinking water pipelines.
Before putting the valve into operation, clean and purge the
corresponding pipeline sections.
4.2 Installation location
The installation location of the valve must be selected to provi-
de sufficient space for function checks and maintenance works
(e.g. dismantling and cleaning of the valve).
If the valve is installed in the open, it must be protected against
extreme atmospheric influences (e.g. formation of ice) by ade-
quate covers.
To ensure the trouble-free function and long service life of the
valve, several factors have to be taken into account when posi-
tioning the valve.
4.2.1 Stable flow
Subcritical and even flow ensures the vibration-free position of
the valve in the flow even at higher flow velocities (see Section
3.3). To achieve stable flow, a straight damping zone of 3 x DN
should be provided upstream of the VAG TOP-STOP
Diaphragm Non-Return Valve (see Fig. 3).
If it is not possible to provide the required damping zone, tur-
bulences in the flow may cause the diaphragm to vibrate, redu-
ce its service life and result in disturbances in the equipment.
In consultation with the manufacturer, the flow velocity
should be reduced to 2 m/s (e.g. by using a larger nomi-
nal diameter) or maintenance intervals should be shorte-
ned as a counter-measure.
We recommend an outlet section of 3 x DN downstream of the
VAG TOP-STOP Diaphragm Non-Return Valve to allow the flow
to steady upstream of subsequent pipeline installations. For
this purpose please refer to the technical documentation on the
corresponding installations.
4.2.2 Flow velocity
The VAG TOP-STOP Diaphragm Non-Return Valve is suitable
for operation at a maximum flow velocity according to EN 1074-1
(see Section 3.3).
For safe operation, installation with an upstream damping zone
is required (see Section 4.2.1, Figure 3)
If the provision of a damping zone is impossible, the minimum
flow velocity must be reduced according to the installation
situation (e.g. < 2 m/s when installed downstream of elbows).
If the above instructions are not complied with, the diaphragm
will flutter and thus be subject to increased wear and tear which
may result in a shorter service life.
Figure 3: Stable flow
4.3 Installation position
The VAG TOP-STOP Diaphragm Non-Return Valve may be
installed in the pipeline in any position. When installing the
valve, please observe the flow arrow on the valve body to
obtain the proper flow direction.
The VAG TOP-STOP Diaphragm Non-Return Valve closes relia-
bly in all operating positions if there is sufficient back-pressure
(Figure 4).
Flow rate
Damping zone
Pump
