Saeco RI9722/11, Service Manual

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4. FUNcTION/TIMING INCANTO
Saeco International Group
REV.5 FEB.2005 Saeco Austria AG
4.9.2. Froth valve functioning
The backpressure in the froth valve and, consequently, on the membrane of the froth valve, is minimal
when the flow valve is open. Accordingly, the valve needle is kept by the spring pressure in almost home
position and the flow is at maximum (Fig. 3).
If the flow valve moves towards a minimum position, a backpressure results which creates an increased
pressure on the membrane in the valve chamber. The membrane yields to the pressure and the valve needle
further reduces the flow speed (Fig. 4).
Fig. 3 Fig. 4