OPERATING MANUAL
07-2022
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The following figures (
fig.1
) show the position of the eccentrics for double eccentric butterfly valves.
Fig. 1. Disk positions depending on the butterfly valve opening angle.
The first eccentric (a) causes the disc rotation axis to be outside of the sealing surface axis. Such construction
ensures full sealing around the entire circumference between the body welded seat and the rubber sealing ring.
The second eccentric (b) is an offset of the butterfly valve disc axis in relation to the butterfly valve axis (body
axis).
It serves to minimise the compressive stress of the sealing ring when the butterfly valve is opened.
•
The valve without a gearbox forms an assembly that can be adapted to various control devices (gearboxes,
actuators).
To ensure proper leak-tightness of the valve, an operator can only be installed by an
authorized service of Fabryka Armatur JAFAR.
The operator must ensure a stable closure actuation angle
within:
➢
0 - 90
for the fully open and fully closed motion;
➢
15
- 90
for flow control (damping);
and the proper operating torque (see Table 1). Long-term operation of the valve with an operator as a flow
damping valve may cause wear of the sealing insert and result in leaks through the closed valve.
