Flowserve ZK210 - Manual (Page 6)

6
Explanatory Notes
(continued)
Function
Every control valve is equipped with a ZK radial stage nozzle .
This is a system comprising several sleeves nesting within one another and containing radial
orifices drilled in them. By rotation of the sleeves, the orifices are shifted relative to one
another, thus forming a large number of throttling points in parallel, with turbulence chambers
(expansion chambers) in between.
The throughput through the ZK radial stage nozzle
is set by means of the valve plug.
Depending on its position, this valve plug opens up the individual orifices partially or
completely, thus producing different flow rates.
As a result of this design, the pressure drop is reduced in steps and the medium flowing
through is split up into many partial flows. This ensures high resistance to wear and reduces
the noise level.
On the valve plug, there is a control edge which is separate from the seat surface and closes
the orifices of the sleeve insert before the valve plug comes to rest completely against the
seat ring. As a result, wear is prevented on the surfaces of the seat. Because of the multiple,
step-by-step expansion in the turbulence chambers, the pressure drop in the region of the
seat is minimised.
Control valve ZK 210: 3-stage radial nozzle, ∆p
max
100 bar
Setting slots Control edge
Orifices of sleeve
insert (sleeves
not shifted)
Seat
Flash chambers
(sleeves shifted) Orifices