417101382_MFV_II-III.doc
- 18 -
Rev: 5-02/10
4
Function and Use
4.1
Functional Description
The following functions are done by two spring loaded diaphragms:
a) Pressure holding function
Protection against sucking empty at under pressure or empty lifting due to creation of an
artificial counter pressure.
Fig. 4.1
In normal operation a diaphragm valve must be
pressed against a preset spring pressure of 1
bar for passage to the metering line by the
delivery pressure of the metering pump.
b) Overpressure function
Protection against impermissible overpressure in the metering line (adjustable opening
pressure).
Fig. 4.2
If the counter pressure in the metering line rises
above a spring pressure set at the multifunction
valve (see chapter
5.3
Setting opening pressure
overpressure function), a diaphragm valve
opens and delivery into the bypass takes place.
c) Vent
function
Suction aid for first-time startup of the pump.
Fig. 4.3
By turning knob 2 to the right (pressure relief
valve) the metering counter pressure is relieved.
)
NOTE
If the knob is turned by more than
approx. 20°, the knob snaps back to
the initial position.
d) Emptying function
Emptying and therefore relief of the pressure line at machine standstill.
Fig. 4.4
The metering line is emptied by turning the two
knobs 1 and 2.
)
NOTE
If the two knobs are turned by more
than approx. 20°, they snap back to
the initial position.
