Specifications

SECTION IV. CALIBRATION
4 -1. CHECK POWER POSITIONER CALIBRATION.
Use the following procedure to check calibration of
power positioner. Figure 4-1, Calibration Flowchart is
provided as a quick reference guide.
IS PERCENTAGE
OF TRAVEL OF
DEVICE EQUAL TO
CORRESPONDING
PERCENTAGE OF
CHECK STROKE
POSITION FOR
EACH PERCENT
OF SIGNAL LISTED
IN TABLE 4-2
NOTE
If cam was shaped (characterized), values of
percent output desired must be recorded
upon instalIation in Table 4-1, Schedule D.
This is necessary to check calibration. If
values were not recorded, refer to Appendix
A, paragraph A-2.b and calculate correct
positions using formulas.
a. Device Travel.
1. Measure distance that the controlled device’s
driven lever arm travels from 0% signal air
to 100% signal air. Record this as total
distance.
2. Set signal air to 0%.
I
1
I
IS PISTON IN
PROPER POSITION
FOR EACH SIGNAL
AIR PRESSURE?
CALIBRATE LINKAGE
PARAGRAPH 4-4.
CALIBRATE STROKE
AND I/P. REFER TO
PARAGRAPHS 4-2
POW16
3. Measure controlled device’s driven lever
arm travel from 0% to 10% signal air.
Divide measurement by total distance
measured in step a. Record this as the
percentage of output travel for 10% signal
air. Measure and record percentage of output
travel in the same. fashion in 10%
increments up to 100% signal air.
4. Compare recorded readings with percent
driven lever travel in Table 4-l. Use
ICSPtXth
columns for characterized
systenls, linear, square root, or square. cams.
If recorded percentages of travel are equal to
those in Table 4-1, the system does not need
calibration. If recorded readings do not
equal those in Table 4-l continue checking
procedure.
Figure 4-1. Calibration Flowchart