Ecolab Elados EDPL V15 Notice Technique page 42

When metering in pipes with a vacuum, a pressure maintaining valve
is to be installed in the metering line.
NOTE
In order to prevent the metering medium from escaping while the
pump is stopped, we also recommend installing a solenoid valve
which is released with the pump.
Item Description
1 Injection valve / Metering valve
2 External release
3
Solenoid valve
4 Pressure maintaining valve
The metering point should not be positioned
below the discharge container as this
arrangement creates a risk of the discharge
container being siphoned empty(see Fig. 7.4).
If this arrangement is not possible for technical
reasons, an appropriate pressure maintaining
valve must be installed (see Fig. 7.5).
Item Description
1 Overflow valve
2 Injection valve / Metering valve
3
Pressure maintaining valve
For long metering lines or rigid piping, a pulsation attenuator (1) must be
installed in the pressure tube
(directly after the metering pump's pressure valve) to prevent pressure
shocks.
Suction lines should be kept as short as possible. Long and
labyrinthine suction lines can lead to accumulation of air in the
system. The suction height must be a max. of 2 m and the maximum
flow rate is 0.3 m/s.
(Also refer to chapter
The suction line must always be installed sloping upwards towards the
metering pump.
For system designs with a suction tube length of more than about 3 m
and/or that must reach a suction height of > 2 m, an appropriate lifting
vessel must be installed to support the suction process. The lifting
vessel must be positioned above the pump.
Item Description
1
Lifting vessel
2 Solenoid valve
417102213_EDP L_V15.docx
A pressure maintaining valve or a metering valve is not
a shut-off device which is absolutely tight sealing.
13.4 "Technical specifications")
Fig. 7.4
Fig. 7.7
Fig. 7.8
Fig. 7.9
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Fig. 7.3
Fig. 7.5
Fig. 7.6
Rev. 1.10.11