GPR-1200 Portable ppm Oxygen Analyzer - Advanced Instruments Inc.

Symptom Possible Cause Recommended ActionErratic O 2 readingorNo O 2 readingErratic O 2 readingorNegative O 2 readingorNo O 2 readingpossiblyaccompanied byelectrolyte leakageTest sensor independent from analyzerChange in sample pressureDirty electrical contacts in upper section ofsensor housingCorroded solder joints on sensor PCB fromcorrosive sample or electrolyte leakage fromsensorCorroded spring loaded contact in uppersection of sensor housing from liquid insample or electrolyte leakage from sensorLiquid covering sensing areaImproper sensor selectionPresence of interference gasesPresence of sulfur gasesUnauthorized maintenanceSensor nearing end of lifePressurizing the sensor by flowing gas to thesensor with:the vent restricted orSHUT OFF valve closedandsuddenly removing the restriction draws avacuum on the sensororpartially opening the valves upstream of theanalyzer when using a pump downstream ofthe analyzer to draw sample from a process atatmospheric pressure or a slight vacuumA pressurized sensor may not leak but stillproduce negative readings.Placing a vacuum on the sensor in excess 4”of water column is strongly discouraged.The front sensing membrane is .000625 thick,heat sealed to the sensor body and subject totearing when vacuum is suddenly applied.A premature adjustment of the ZERO OFFSETpotentiometer is a common problemRemove sensor from housing. Using a volt-meter setto uA output; apply the (+) lead to the outer ring ofthe sensor PCB and the (-) lead to the center circleto obtain the sensor’s output in air. Contact factorywith result.Sensors without PCB use mV setting.Calibrate the analyzer (calibrate at pressure andtemperature of sample)Clean contacts with alcohol (minimize exposure timeof MS sensor to ambient air to extent possible)Replace sensor and return sensor to the factory forwarranty determinationUpper section of sensor housing: Clean contacts withalcohol, flow sample or zero gas for 2-3 hours toflush sample system and sensor housingSensor: Replace if leaking and return it to the factoryfor warranty determinationWipe with alcohol and lint free towel or flow sampleor zero gas for 2-3 hours to flushReplace GPR/PSR sensor with XLT sensor when CO 2or acid gases are presentConsult factoryReplace sensor and install scrubberReplace sensor, obtain authorized serviceReplace sensorZero the analyzer. If not successful replace thesensorAvoid drawing a vacuum on the sensorFrom MAIN MENU select DEFAULT ZERO30