Owner's manual

h.
I.
j.
k.
1.
In.
n.
0.
P.
Increase signal to 100%.
Meawe distance from top surface of packing
cover to bottom edge of cl&s head. Label this
distance “B”.
Subtract distance “A” from distance “B”. Record
this as total piston travel.
Set signal air to 0%.
Send a 10% signal to power positioner.
Measure distance from top of packing cover to
bottom of clevis head.
Subtract distance “A” tiom 10% signal and
record this as piston travel for 10% signal air.
Measnre and record piston travel for 20% to
100% signal air in 10% increments.
Compare actual piston movement with piston
movement provided in Table 4-2. Use correct
schedule for cam installed on power positioner.
Schedule “A” is for power pxitioners with linear
cams, schedule “B” is for square root cams,
schedule “c” is for square cams, and schedule
“D” is for a characterized cam. If actual piston
movement is equal to piston movement provided,
refer to paragraph 4-4 and calibrate linkage. If it
is not equal, calibrate piston movement
(paragraph 4-2). Calibrate J/F’ signal converter
@amgraph 4-3).
4-2. STROKE CALIBRATION. Use the following
procedure to adjust power positioner’s piston
movement (stroke).
a. Dhwt Acting Power Positioner.
WARNING
Before performing any maintenance,
adjustment, or repair action on power
positioner, shut off supply air, signal air,
and any electrical signals to power
positioner. Isolate power positioner from all
systems connected to the power positioner.
Severe injury or death may result from
large torque power positioner is capable of
producing, or from electrical shock.
1. Remove power positioner from service.
2. Purge supply air and signal air lines to
remove water and debris.
3. Making sure bypass valve is closed, set
signal air to 0%. Refer to Table 4-3 for
percent to signal air pressure conversion.
4. Loosen set screw (1, Figure 4-2) securing
spring socket (2) in place.
Table 43. Direct and Inverse Calibration Signal Pressures.
POWER POSITIONER ACTION
STROKE
POSITION
0%
100%
DIRECT INVERSE
PNEUMATIC I/P
PNEUMATIC
I/P
O-30 3-15
3-21 O-60 O-30 3-15 O-27 O-60
Psig PSig Psig Psig Psig PSig psig Psig
0 3
21 0 30 15 3 60
30 15
3 60 0 3 21 0