GB
MU1H-1207GE23 R0420
5
valve must be fitted to allow for water expansion
and prevent the pressure rising above the permitted
level.
CAUTION!
If soldered union connectors are used the backflow
preventer must not be connected to the union
connectors during soldering.
4.3 Commissioning
As supplied the electrical changeover valve
is closed and
the backflow preventer is in the shut-off position.
Commissioning should be in the following sequence:
1.
Connect the electrical changeover valve
of the
backflow preventer with the appropriate signal emitter
on the downstream system (pressure sensor, flow
sensor - e.g. SW 295 -, water level sensor etc.).
2.
Install electrical power supply.
3.
Slowly open shut-off valve
(The backflow
preventer goes to the open position when the supply
pressure exceeds the inlet opening pressure setting).
4.
Slowly open shut-off valve
, fill the system and
vent.
5.
After filling the system, or when no more water is
being drawn, the emitter must operate the changeover
valve
, whereby hydraulic switchover occurs and
the backflow preventer goes to the maximum shut-off
position.
6.
If, when water is being drawn off from the downstream
system, the inlet pressure falls to the set opening
pressure of the backflow preventer, then the backflow
preventer automatically opens to provide a minimum
air gap of 20 mm.
7.
The operating position is indicated on the spring
bonnet
•
Shut-off position: Green spring cap
is visible
•
Flow position: Green spring cap
is not visible
Correct opening pressure
The set pressure of the backflow preventer is determined by
the maximum pressure which will occur in the downstream
system. It must be at least 0.5 bar higher than the pressure in
the system to be protected.
If the highest possible dirty water level in the system to be
protected or the highest take off point are 10 metres above
the installation location of the backflow preventer, then the set
pressure must be greater than or equal to 1.5 bar. The
backflow preventer begins to go to the shut-off position if the
inlet pressure falls to the set pressure (in this example,
1.5 bar)
Set opening pressure: pa > 0.5 bar plus:
•
The pressure head difference H to the highest
possible takeoff point after the backflow preventer
•
The permissible maximum excess pressure pü in the
appliance or installation
CAUTION!
The higher the set opening pressure, the sooner the
shut-off position will reached.
5
Maintenance
In order to comply with EN 806-5, water fixtures must
be inspected and serviced on an annual basis.
As all maintenance work must be carried out by an
installation company, it is recommended that a
servicing contract should be taken out.
In accordance with EN 806-5, the following measures must
be taken:
5.1 Inspection
5.1.1 Testing of function
•
Close the valve
fitted before the backflow
preventer.
•
Relieve the pressure in the isolated section through
the small drainoff valve
•
Visually check that the backflow preventer goes to
shut-off position.
5.1.2 Checking for seal
•
Visually check that no water is emitted when backflow
preventer is in the flow position
These inspections and tests should be carried out at least
twice a year by the user or by a specialist (depending on
operating conditions, it may be necessary to carry out these
tests and inspections more frequently).
5.2 Maintenance
The backflow preventers are safety devices which require
very little maintenance and which are installed to prevent
backflow of uncleaned water into the supply network, into
separate systems or into other sections of an installation.
Depending on operating and flow medium conditions, to
ensure trouble free operation it is necessary at fixed time
intervals to check seal components, piston guides and rating
springs and where necessary replace them.
6
Disposal
Observe the local requirements regarding correct waste
recycling/disposal!
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Accessories
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8
Spare Parts
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