Detcon FP-624D-HT - Manual (Page 40)

Model FP-624D-HT
FP-624D-HT Instruction Manual Rev. 1.1 Page 36 of 44
Probable Causes: Failed sensor, cal gas not removed at appropriate time, problems with cal gas and delivery,
or background combustible gases preventing clearing
Confirm that no combustible gasses are present in background.
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 and gas factor is set
Check for obstructions through stainless steel sinter element (including being wet).
Replace the plug-in sensor.
Poor Calibration Repeatability
Probable Causes: Failed sensor, use of wrong cal gas, problems with cal gas and delivery, or poison or
inhibitor gases
Check for adequate sensor life.
Check bridge voltage (should be 2.7 +/- 0.2VDC).
Check validity of span gas and flow rate (check MFG date on cal cylinder).
Check for obstructions through stainless steel sinter element (including being wet).
Evaluate area for presence of poisoning or inhibiting gases as listed in Section 2.3.
Increase calibration frequency.
Note the sensor’s serial # and report repetitive problems to Detcon’s Repair Department.
Replace plug-in sensor.
Unstable Output/ Sudden spiking
Possible Causes: Unstable power supply, inadequate grounding, or inadequate RFI protection
Verify power source is stable.
Verify field wiring is properly shielded and grounded.
Contact Detcon to optimize shielding and grounding.
Add Detcon’s RFI Protection Circuit accessory if problem is proven RFI induced.
Nuisance Alarms
Check condulet for accumulated water and abnormal corrosion on terminal blocks.
If nuisance alarms are happening at night, suspect condensation in condulet.
Add or replace Detcon’s
Condensation Prevention Packet P/N 960-202200-000.
Investigate the presence of other target gases that are causing cross-interference erroneous readings.
Determine if cause is RFI induced.