Multi-layer diaphragm pump
Serie 409.2 ML
Operating instruction
20
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Technical modifications reserved!
TA 431
Rev.
8 en
06/2015
8.1.2
How to prevent a backflow of the
dosing medium
When the dosing line is linked with a main line:
•
install an injection fitting (dosing valve).
Main line
Injection fitting
Tank
Multi-layer
diaphragm pump
Shut-off fitting
Suction line
Fig. 22 Installation of injection fitting
CAUTION!
There will be an unintentional mixture in the dosing line if
a possible backflow from the main line is not eliminated.
CAUTION!
Pay attention to/avoid chemical reactions arising from a
backflow of the dosing medium.
8.1.3
How to eliminate undesired siphoning
When dosing into a main line with negative pressure:
•
install a pressure keeping valve into the dosing line.
CAUTION!
When installing a pressure keeping valve, make sure that
an uncontrolled dosing is avoided (by a positive pressure
difference (≥ 1bar) between pressure and suction side).
Main line
Pressure keeping
valve
Injection line
Multi-layer
diaphragm pump
Dosing line
Shut-off fitting
Tank
Suction line
Fig. 23 Installation of pressure keeping valve