18
19
www.vexve.com
NOTE:
·
It is recommended to fill the pipeline via by-pass valves.
·
The pipeline must be flushed carefully, see chapter 4.8 for instructions
Figure 23. By-pass valve.
Figure 24. Pipeline needs to be flushed after
valve installation
It is recommended to fill the pipeline via by-pass valves in order to avoid pressure shocks and to reduce
forces caused by opening the butterfly valve under pressure (see Figure 23.).
To avoid pressure shocks and to reduce the
forces caused by opening the valve under pres-
sure, a by-pass valve must be used in
connection with butterfly valves
(see Figure 23.).
4.7 Before commissioning
4.8 Flushing
Pipeline needs to be flushed carefully after the
valve installation.
Before starting the flushing, turn the valve disc
so that the opening angle is 30–40°.
Close the valve gradually during the flushing until
the opening angle is approximately 5-10°.
Decreasing the opening angle increases the
velocity of the flow through the valve. This
produces efficient removing of impurities from
sealing surfaces of the valve.