3.2 Applications
Due to its EPDM sealing materials the standard version of the
VAG TOP-STOP valve can be used for the following fluids:
• Water,
• Raw water and cooling water,
• Weak acids and alkaline fluids
For use with fluids containing oil or gas, the TOP-STOP valve is
also available with an NBR diaphragm.
Due to their abrasive effect, solids contained in the water may
reduce the service life of the diaphragm.
Larger particles of solids in the water may clog the non-return
valve. Therefore the valve must not be used with this kind of
fluids.
For information about the corresponding temperature limits,
please refer to the product-related technical documentation
(KAT 1543-A).
In case of deviating operating conditions and applications,
please consult the manufacturer.
3.3 Permissible and impermissible modes of
operation
The maximum operating temperatures and operating pressures
specified in the technical documentation (KAT 1543-A) must not
be exceeded.
The pressure applied to the closed valve must not
exceed its rated pressure.
The maximum permissible flow velocity (stable flow) is
according to the EN 1074-1 standard.
Valves with PN 10: 3 m/s
Valves with PN 16: 4 m/s
Any exceptions from the above require the manufacturer's
express written approval.
In case of turbulent flow (e.g. installation downstream of elbo-
ws and similar parts) the flow velocity must be reduced accor-
dingly in consultation with the manufacturer. Should this not be
possible, the valve must be serviced at shorter intervals.
2.2 Storage
The TOP-STOP Diaphragm Non-Return Valve is to be stored in
a way that ensures that the diaphragm is in closed position and
free from any loads. Preferably the valve should be placed on
its inlet-side flange (see Fig. 1).
The elastomeric parts (seals) must be protected against direct
sunlight and/or UV light as otherwise their long-term sealing
function cannot be guaranteed. Store the valve in a dry and
well-aerated place and avoid direct radiator heat. Protect any
assembly units important for the function such as the dia-
phragm and the cone of the seat against dust and other dirt by
adequate covering.
Do not remove the protective caps of the connections / flanges
and the packaging materials until immediately prior to assembly.
The valve can be stored in ambient temperatures ranging from
-20 °C to + 50 °C (protected by adequate covers). If the valve
is stored at temperatures below 0 °C, it should be warmed up
to at least +5° C before installation and before it is put into ope-
ration.
3. Product features
3.1 Features and function description
The VAG TOP-STOP valve is a diaphragm non-return valve in
full flange design and can be used between two flanges under
full operating pressure. The rubber diaphragm is located in the
cone of the seat of the body and opens automatically even
under low fluid pressure. In the opposite direction, the valve is
also sealed by pressure and it is resilient seated. Due to its
design the valve closes fast and emits only little noise. Water
hammers are adequately absorbed. To ensure complete sea-
ling, a back-pressure of about 3 m water column is required.
The valve is supplied with two drain plugs as a standard (see
Fig. 2).
As an alternative, a bypass can be installed instead of the drain
plugs (not included in the VAG range). It allows the forced
bypassing of the diaphragm to permit the return flow of the
fluid.
Figure 2: Standard model VAG TOP-STOP Diaphragm Non-Return Valve
4. Installation into the pipeline
4.1 Conditions required on site
When installing the valve between two pipeline flanges, these
must be coplanar and in alignment. If the pipes are not in alig-
nment, they must be aligned before installation of the valve, as
otherwise this may result in impermissibly high loads acting on
the valve body during operation, which may eventually even
lead to fracture.
When installing the valve into the pipeline, make sure it is as
tension-free as possible. The pipeline forces transmitted to the
valve must not exceed the values specified in DIN EN 1074-3.
