Detcon FP-524D-HRT - Manual (Page 44)

Model FP-524D-HRT
FP-524D-HRT Instruction Manual Rev. 0.1 Page 40 of 48
6. Troubleshooting Guide
Refer to the list of failsafe diagnostic features listed in Section 3.6.2 for additional reference in troubleshooting
activities. Listed below are some typical trouble conditions and their probable cause and resolution path.
Figure 22 Replaceable Combustible Gas Sensor
Sensor Current/Voltage Fault
Probable Cause: Plug-in sensor has failed
Remove plug-in sensor and verify resistance between PIN 5 and PIN 7 and PIN 2 and PIN 4 using an
ohmmeter. At room temperature, the normal reading range should be 2.5-3.5 ohms for both catalytic beads.
Replace plug-in sensor if either measurement is open circuit or significantly out-of range.
Zero Fault
Probable Causes: Plug-in sensor has drifted
Perform AutoZero calibration per Section 3.4.1
Replace the plug-in sensor.
AutoSpan Calibration Faults – (Range, Stability, and Clearing)
To clear any AutoSpan Calibration fault, the AutoSpan process must be completed successfully (Section3.4).
Range Fault
Probable Causes: Failed sensor, cal gas not applied or not applied at appropriate time, or problems w/ cal gas
and delivery
Check bridge voltage (should be 2.7 +/- 0.2VDC).
Check validity of span gas and flow rate (check MFG date on cal cylinder).
Make sure correct cal factor is set
Check for obstructions through stainless steel sinter element (including being wet).
Replace the plug-in sensor.
Stability Fault
Probable Causes: Failed sensor, empty or close to empty cal gas cylinder, or problems w/ cal gas and delivery
Check bridge voltage (should be 2.7 +/- 0.2VDC).
Check validity of span gas and flow rate (check MFG date on cal cylinder).
Make sure correct cal factor is set
Check for obstructions through stainless steel sinter element (including being wet).
Replace the plug-in sensor.
Clearing Fault