wT 1255/12
Page 18
12
Conversion of an on/off Valve to a Control Valve
The difference between a KVN piston valve and a KVRLN control valve is the lantern bush.
The control lantern bush features a defined geometry, which results in an almost linear
flow curve and simplifies the control of media flows.
Due to the fact that the sealing system of control valves corresponds to that of piston
valves, the shut-off function is also present in the bore.
The advantage of using the same sealing components lies in the fact that it enables the
conversion of an installed piston valve – requiring only the exchanging of the lantern bush
– into a control valve.
12.1
Conversion instruction
»
Depressurize and purge pipe
»
Fully open piston valve
»
Screw off bonnet securing hex nuts (Pos.27) and remove belleville washers (Pos.33)
»
Turn handwheel (Pos. 3) clockwise (closing direction) until bonnet is moved out of
the body and bonnet flange is located above the stud bolts
»
Subsequently lightly turn bonnet (Pos. 2) out of position, so that the bonnet flange
can rest on the stud bolt faces (Pos. 25). Turn the handwheel counterclockwise
(opening direction) until the piston (Pos. 4) is fully pulled out of the upper valve ring
(Pos. 14) (see Fig. 1)
»
Remove bonnet with the handwheel, spindle and piston and remove valve ring (Pos.
16) from the bonnet
»
Remove the thrust piece (Pos. 19) and upper valve ring (Pos. 14) by means of a
ring extractor hook (see Fig. 2)
»
Remove the lantern bush (Pos. 5) by means of a lantern bush drawer without
damaging the surface of the body’s bore (see Fig. 3)
»
Remove the lower valve ring (Pos. 9) by means of a ring extractor hook without
damaging the surface of the body’s bore
»
Clean the bore of the body and the valve ring seat
»
Installation of the lower valve ring into the body by means of KX-GT assembly tool.
Do not use any grease or lubricant ((DN 65/DN 80/DN 100 see Fig. 4, DN 125/DN
150/DN 200 see Fig. 5)
»
Insertion of the control lantern bush. Ensure that no lantern bush root face rests on
the valve output side in order to achieve an optimized K
v
-value
»
Installation of the upper valve ring by means of KX-GT assembly tool. Note that no
grease or lubricant may be used here, either
»
Insert thrust piece (Pos. 19)
»
Press in the new valve ring (Pos. 16) into the body’s bore by means of assembly
tools
»
Take the bonnet and screw out spindle until it recedes no further (turn handwheel
left)
»
Position bonnet (Pos. 2) on the valve body, after thorough lubrication of the neck of
the bonnet. Hammer it down with a plastic hammer until there is enough
supernatant of the stud bolt (Pos. 25) above the bonnet flange for the screwing of
the bonnet securing nuts (Pos. 27)
»
Place belleville washers (Pos. 33) and screw on hex nuts (Pos. 27) with a few
convolutions