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- valves in which there is an inflow over the disc are equipped with a balancing disc as shown below. Turning the handwheel to the
left raises the balancing disc which results in equalization of upstream and downstream pressure. After pressure equalization the
valve can be opened completely. The balancing disc operation is effective only in closed systems. In an open system where it is
impossible to equalize pressure the balancing is ineffective. In this case, one should consider introduction of other structural
solutions, e.g. a by-pass.
- The maximum differential pressure that can apply on both sides of the closing valve (the valve is closed) in valves where
there is flow under the plug see in the table below.
PN
differential pressure
[bar]
DN15-100
DN125
DN150
DN200
DN250
DN300
6
6
6
6
6
6
6
16
16
16
16
14
9
6
25
25
25
21
14
9
6
40
40
33
21
14
9
6
In order to assure safety performance, each valve (especially rarely used) should be surveyed on regular basis.
Inspection frequency should be laid down by user, but not less than one time per month.
7.
SERVICE AND REPAIR
All service and repair jobs should be carried out by authorized staff using suitable tools and original spare parts. Before
disassembly of complete valve from the pipeline or before service, the pipeline should be out of operation. During service and
repair jobs it is necessary to decrease pressure to 0 bars , valve temperature to ambient temperature and to use personal health
protectives in pursuance of existing threat. After valve disassembly it is necessary to replace flange connection gaskets between
valve and pipeline.
Lift up the gland
Fill the gland packing
Disc
Balancing disc
