Remote Set Point Zero And Span Adjustment; Remote Set Point Linearity Adjustment - Fisher 4195 KB Series Instruction Manual

4195KA, KB, and KC Series
3. Set the length of link A (key 116) so the lever arms
of pivot assembly A and pivot assembly B are parallel
and link A is perpendicular to them.
4. Set the length of link B (key 126) so the set point
indicator indicates mid-scale on the process scale
span.
5. Replace the tie bar (key 106) and install the two
screws (key 103).
Remote Set Point Zero and Span
Adjustment
For routine remote set point zero and
span calibration, refer to the appropriate
procedures in section 3 or 4. Use the
following maintenance remote set point
zero and span adjustment procedures
only if difficulty is encountered with the
routine procedure or nonlinearity oc-
curs.
Refer to figures 5–19 and 5–23 for adjustment loca-
tions.
1. Decrease the remote set point pressure to 0 per-
cent of the remote set point input range.
2. The set point indicator should indicate the lower
limit of the process scale span. If not, loosen the ad-
justment screw on link A (key 116), and adjust the
length so the set point indicator points to the lower
limit of the process scale. Tighten the screw.
3. Make fine zero adjustments by loosening the zero
adjustment locking screw (key 102) and turning the
zero adjustment screw (key 108). Tighten the locking
screw. Refer to figure 5–23 for the screw locations.
4. Apply remote set point pressure equal to 100 per-
cent of the remote set point input range.
5. The set point indicator should indicate the upper
limit of the process scale span.
6. To increase the span, proceed as follows:
a. Turn the remote set point span adjustment
screw clockwise.
b. To increase the span further than the adjust-
ment screw allows, move both ends of link A (key
116) to the right.
c. Make fine adjustments with the remote set point
span adjustment screw.
7. To decrease the span, proceed as follows:
a. Turn the remote set point span adjustment
screw counterclockwise.
5–34
Note
b. To decrease the span further than the adjust-
ment screw allows, move both ends of link A (key
116) to the left.
c. Make fine adjustments with the remote set point
span adjustment screw.
8. Repeat the adjustments until the upper and lower
indications are aligned with the upper and lower limits
on the process scale.
9. Adjust the remote set point pressure for 50 percent
of the remote set point input range.
10. The set point indicator should indicate mid-scale
2 percent of the process scale span. If the error is
within 2 percent, proceed to step 11. If the error is
greater than 2 percent of the scale span, proceed to
the remote set point linearity adjustment procedure.
11. Adjust the set point indicator to mid-scale 1 per-
cent of the process scale span by loosening the zero
adjustment locking screw and turning the zero adjust-
ment screw. Tighten the locking screw.
12. Adjust the remote set point pressure to the upper
and lower limits of the remote set point input range
and make sure the set point indicator is still within 1
percent at the lower and upper limits of the process
scale.
13. Perform the appropriate flapper alignment proce-
dure and, if necessary, the process indicator zero and
span calibration procedure in section 3 or 4.

Remote Set Point Linearity Adjustment

Adjust the linearity by loosening and repositioning the
linearity adjustment screw in the curved slot on the
lever arm of pivot assembly B (key 115). Adjusting the
linearity affects the zero and span adjustment.
1. Adjust the remote set point pressure to 50 percent
of the remote set point input range. The set point indi-
cator should indicate mid-scale 1 percent of the pro-
cess scale span. If not, make fine adjustments by
loosening the zero adjustment locking screw and turn-
ing the zero adjustment screw.
2. Adjust the remote set point pressure to 0 percent of
the remote set point input range and note the indicator
position relative to the process scale lower limit.
3. Adjust the remote set point pressure to 100 percent
of the remote set point input range and note the indi-
cator position relative to the process scale upper limit.
4. If the greatest misalignment is positive (the set
point indicator is to the right of the process scale lim-
its), loosen the linearity screw and move it clockwise in
the slot. If the misalignment is negative, move the lin-
earity screw counterclockwise in the slot.
5. If the misalignment is greater than 1 percent of the
process scale span at the lower and upper limits, with
one positive and the other negative, perform the re-