17
Model 288A Differential Pressure Indicating Switch
Section 3
2. Gently turn the knurled head of the screw clockwise, pushing the pin
against the movement shaft and lifting the pointer with the arms. Finger
pressure should be suffi
cient to pull the pointer free. If more pressure is
required, an Allen wrench (inserted into head of the screw) can be used.
However, care should be exercised to avoid breaking the pin.
Figure 3.3—Pointer puller (Part No. 9A-0163-0005B)
Indicator Calibration
A complete calibration of the instrument is required whenever the DPU as-
sembly is replaced.
IMPORTANT: Review all procedures, WARNINGS/NOTICES in Appendix A BEFORE
performing this procedure.
1. Securely mount the instrument in an approximately level position and
connect the DPU, as described in Mounting, page A-5.
2. Remove the bezel/lens assembly.
3. Align the linkage between the drive arm and the movement at 50% diff er-
ential pressure (DP) as shown in Figure 3.4. Inspect parts for straightness
and pivot-fi t without binding.
Figure 3.4—Range/linearity adjustment (50% DP)
Summary of Contents for 288A
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