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23
Model 581A Differential Pressure Switch
Section 3
Range, page A-18, and Bellows Unit Assembly (BUA) Replacement, page A-22,
for
details or contact the factory for assistance.
Troubleshooting
For switch troubleshooting tips, see Table 3.2 below. For information related
to the DPU, see Appendix A.
Table 3.2—Troubleshooting
Problem
Possible
Source
Probable Cause
Corrective Action
Low or No
Indication
Indica-
tor, Alarm
Switch
Mechanism
Loose linkage or movement
Tighten or replace
Out of calibration
Calibrate
Pointer loose
Tighten pointer
Dirty or corroded mechanism
Clean or replace
Wiring interfering with move-
ment
Re-route wiring
Dirty mechanism
Clean mechanism
High
Indication
Indicator,
Alarm-
Switch
Mechanism
Loose linkage or movement
Tighten or replace
Out of calibration
Calibrate
Erratic
Indication
Indica-
tor, Alarm
Switch
Mechanism
Linkage dragging or dirty
Adjust or clean
Pointer dragging on scale plate
Adjust pointer position
Inaccurate
or No
Electrical
Alarm
Power
Supply
Blown fuse
Replace fuse
Broken or loose wire
Repair
Alarm
Switch
Switch not properly adjusted
Adjust switch
Dirty or burned contacts
Replace switch