18.4.17
Modulating Valves Type: VSR
7. Maintenance and repairs
14
7 .
M a i n t e n a n c e a n d r e p a i r s
7 . 1
Inspection
The GUTH modulating valve requires very little maintenance. Nevertheless, the regulating element
should be inspected regularly, i.e. after approx. 500 operating hours.
During the inspection, the following should be checked:
During the inspection, the following should be checked:
1. Seals of all sealing points, especially of the spindle and the pneumatic connections.
2. Modulating function of the valve, including its behaviour when the spindle is in the stationary
intermediate position.
3. Condition of the electrical connections
Re 1:
The degree of spindle sealing is indicated by means of a leakage hole for standard modulating valve
models. If the medium egresses from this leakage hole, which is to be found directly below the
clamping bracket at the junction between the upper housing and the lantern, then the spindle seal
(or seal set as appropriate) must be replaced or the valve spindle put in order.
Re 2:
Normal modulating behaviour is indicated by the spindle changing its position rapidly. In the station-
ary intermediate position, a minor oscillation around the target value may be observed. However,
more pronounced oscillation of the spindle and post-regulation of the valve positioner indicate a
fault.
Maintenance intervals:
7 . 2
Replacing the Cone-Seat Assembly
Wear induced by the medium flowing through the cone slot at high speed can alter the state of the
cone and seat in the course of time, leading to modulating behaviour that is no longer acceptable.
The wear can be slowed down by the use of modulating valves with hardened cone-seat assem-
blies or by reducing the flow speed (e.g. through the use of multi-stage cones), but even in such
cases the necessity to replace the cone-seat assembly at some stage must be reckoned with.
Instructions for replacing the seat ring including its sealing elements and the spindle with its sealing
elements are to be found in Section 6.1 of the operating instructions.
NOTICE
• Practical maintenance intervals can only be determined empirically by the user as they depend
on the conditions of operation involving, for instance, hours of use per day, switching fre-
quency, type and temperature of the product, type and temperature of the cleaning agent, sur-
rounding conditions.
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