Specifications

c. Operational Description. The Model PP814T
Torque Type Power Positioner is a pneumatic
driven, double acting piston type power cylinder
in which the linkage lever is positioned to a
specific setting for each input signal. The power
positioner is mounted on a steel floor stand. The
unit is covered and protected by a splash proof
metal dust cover. The power positioner is used to
position devices such as inlet vanes, control
valves, and dampers.
1. Automatic Operation. Figure l-2 depicts a
direct acting power positioner. In this type
of positioner, an increase in signal air
pressure to the receiver causes the
diaphragm to overcome the tension of the
calibration spring and move downward. The
downward motion is transmitted to the pilot
valve through a connecting link. This
positions the pilot valve stem to send supply
air below the piston, forcing the piston,
piston rod, and cylinder lever upward. Air
from above the piston is exhausted through
the pilot valve exhaust tubing and then
through the open exhaust blocking valve.
NOTE
Figure 1-2 depicts the model 8 x 14 power
positioner with the optional handwheel and
airlock. The 8 x 14 power positioner can be
configured without these items. Refer to
Table l-l.
M
TO EXHAWT
BLOCKING VALVE
Figure 1-2. Power Positioner Operation
“5tm-208
1-3