Barton 227C User Manual

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3-6. Complete Calibration (Cont.) (DP=Differential Pressure)
2. Attach linkage between drive arm and
movement. Fig. 3-3 shows alignment
at 50% DP. Inspect parts for straight-
ness and pivot-t without binding.
3. Set pointer at zero on scale by slip-
ping pointer on hub. Hold tip of
pointer and turn hub with wrench.
4. Apply 100% DP. If pointer exceeds
100% on scale,
lengthen range arm.
Remove pressure.
5. Set zero and span,
using hub for zero
adjustment and
range adjust screw
on the movement for span adjustments.
6. Apply 50% DP. If pointer does not indicate 50% scale, a linearity adjust-
ment is necessary. Loosen drive arm screw and move arm to shift pointer
in direction of error (approx. 10:1). Tighten drive arm screw.
7. Release pressure and reset pointer at zero. Check the span. If gear in move-
ment reaches limit of travel as a result of linearity adjustment (step 6), slip
range arm along gear approximately 5 degrees from normal 37.5 degree
angle to approximately 43 degrees. Range arm is slipped by applying pres-
sure to range arm with thumb, while holding gear rmly in place. Retest
pointer response at 50% and 100% DP, and adjust linkage until readings
are acceptable.
8. Apply 0%, 25%, 50%, 75%, 100%, 75%, 50%, 25%, and 0% of DP
consecutively to instrument without overshoot. Lightly tap indicator to over-
come friction. Pointer should accurately indicate each applied pressure.
10. Test instrument repeatability by applying 0%, 50%, 0%, 50% DP. Indicator
should accurately indicate each applied pressure.
11. Set overrange stops to prevent pointer from striking snubbers on scale. See
para. 3-7 (Overrange Stop Adjustment). Tighten all screws. Test setting by
manually moving pointer from zero position to 50%, then let the pointer
return freely. An off-set in zero reading indicates pointer slippage. If neces-
sary, tap pointer hub to tighten it to shaft.
3-7. Overrange Stop Adjustment
1. Apply sufcient pressure to the high pressure housing to deect the pointer
against the snubber on the scale plate. Slide the upper overrange stop
against the drive arm and tighten the overrange stop screw.
2. Apply sufcient pressure to the low pressure housing to deect the pointer
against the zero stop snubber on the scale plate. Slide the zero-stop against
the drive arm and tighten the zero-stop screw.
3. Remove the pointer and calibration scale. Replace the pointer at zero
(adjust zero as necessary). Replace the lens and bezel assembly.
Figure 3-3. Linkage at 50% DP

Barton 227C Specifications

General

Brand	Barton
Model	227C
Category	Measuring Instruments
Language	English