Reference Manual

1−5
Figure 1-7. Three Way Valve with
Balanced Valve Plug
W9045-1
Figure 1-8. High-Performance Butterfly
Control Valve
W4641
for throttling service or for on-off control. Soft-seat
constructions can be obtained by utilizing a liner or
by including an adjustable soft ring in the body or
on the face of the disk.
D Require minimum space for installation
(figure 1-8).
D Provide high capacity with low pressure loss
through the valves.
Figure 1-9. Eccentric-Disk Rotary-Shaft
Control Valve
W8380
D Offer an economic advantage, particularly in
larger sizes and in terms of flow capacity per dollar
investment.
D Mate with standard raised-face pipeline
flanges.
D Depending on size, might require high output
or oversized actuators due to valve size valves or
large operating torques from large pressure drops.
D Standard liner can provide precise shutoff
and quality corrosion protection with nitrile or
PTFE liner.
Eccentric-Disk Control Valve
Eccentric disk rotary control valves are intended
for general service applications not requiring
precision throttling control. They are frequently
applied in applications requiring large sizes and
high temperatures due to their lower cost relative
to other styles of control valves. The control range
for this style of valve is approximately one third as
large as a ball or globe-style valves.
Consequently, additional care is required in sizing
and applying this style of valve to eliminate control
problems associated with process load changes.
They are well-suited for constant process load
applications.
D Provide effective throttling control.
D Linear flow characteristic through 90 degrees
of disk rotation (figure 1-9).
D Eccentric mounting of disk pulls it away from
the seal after it begins to open, minimizing seal
wear.