Emerson NGA 2000 TO2 Section Troubleshooting, Failure to purge down to ppm levels

Page 67

Model NGA 2000 TO2

Instruction Manual

760008-A September 2001

SECTION 5

TROUBLESHOOTING

5-1 TROUBLESHOOTING

The following provides a short list of common troubleshooting tips. Additional information is contained in the Platform Manual.

a.Failure to purge down to ppm levels

Prior to conducting any changes to the system, try running a quick start se- quence (see section 3.4) to see if the oxygen reading goes lower. If the reading does decrease, the sensor has not been allowed sufficient time to consume the dissolved oxygen in the electrolyte. If the reading continues to read high a leak may exist in the sample lines. The number one problem associated with trace oxygen analyzer installation is the occurrence of leaks in your sample plumbing. If the oxygen reading will not come down to ppm levels or is reading higher than ex- pected, the sample plumbing prior to the instrument may have a leak. A quick check can be conducted by observing the oxygen reading at two different flow lev- els; 0.5 and 2.0 scfh. If the oxygen read- ing drops significantly when the flow is increased from 0.5 to 2.0 scfh, this is a good indication that a leak exists.

To check for leaks prior to the sensor, disconnect the Analyzer Module and cap the inlet line. Pressurize the inlet line to 5 - 10 psig and check all connections with a soapy solution (SNOOP®) to identify leaks.

WARNING.

SENSOR DAMAGE

Do not pressure check the sample line with the sensor connected. Over- pressurization of the sensor can result in damage.

b.Flow sensitivity

Check to make sure that your vent line is not blocked. If you see a rise in reading with an increase in flow, you may be over- pressurizing the sensor due to a blocked vent. Since the sensor is a partial pres- sure measuring device, an increase in sample pressure will cause an increase in reading. If the reading drops with in- creased flow, conduct the leak check out- lined in the troubleshooting tip above.

c.Erratic and very insensitive readings

Check to see that the electrolyte level is within the limits indicated on the reservoir. Add distilled water as required. If the level is within limits, the electrolyte may have been contaminated. Refer to sec- tion 4.2 above for proper procedure to re- place electrolyte. If replacement of electrolyte does not improve the perform- ance of the sensor, the sensor may have been damaged due to over-pressurization or poisoning. Sensor replacement may be required as described in section 4.3 above.

Rosemount Analytical Inc. A Division of Emerson Process Management

Troubleshooting

5-1

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Contents Model NGA 2000 TO2 Essential Instructions Model NGA 2000 TO2 Table of ContentsMaterial Safety Data Sheet System & Network I/O Module Controls SetupAnalyzer Module Interconnection with Instrument Platform List of IllustrationsModel NGA 2000 TO2 Definitions Preface Intended USE StatementSafety Summary Model NGA 2000 TO2 Compliances DocumentationGlossary of Terms System SoftkeysTypical Applications Section Description and SpecificationsFeatures OverviewTrace Oxygen Detector Coulometric Principle Trace Oxygen Analyzer Module Top View Physical SPECIFICATIONS1General SampleGas Connections Model NGA 2000 TO2 Electrolyte Addition Section InstallationUnpacking ElectrolyteSample Flow GasesGAS Connections GAS OverpressureSensor Damage Leak TestElectrical Connections Electrical Shock Hazard Analyzer Module Interconnection with Instrument Platform Outline and Mounting Dimensions Back Panel Connections Displays & Operating Keys OperationMenu Lines & Softkey Functionality Analyzer basic controls calibration & setup…Measure Status… Channel Lock… MFG Data Entering & Changing Variables Signal on mini-bargraphMeasure Back… Ppm O2 Measure Mode DisplayDisplay Status… Main… Channel BasicCal Module Manufacturing Data Displays Startup & Initialization LCDReset AbortInitiate quick start Quick StartMeasure Status… Back… Display Status… Main… Channel Basic CONTROLS, Setup and StatusPower supply voltages… Measure Back… Analyzer Channel StatusDisplay Status… Single Component DisplayMain… Channel BasicCal Multi Component Display Select Status… Tags Off LCDResetRange number Basic Controls and SetupRange number Operation StatusBrightness 70 % Display ControlsBrightness and Contrast Display controls…Measure Channel Back… Expert Controls and SetupAnalyzer and I/O, expert controls & setup… Analyzer module controls…Gas Scale Factor Calibration ProcedureAir background gas concentration Gas scale factor…Span gas 90.0 ppm Measure Status… Back… Span CalibrationAlarm generation isRe AlarmsAlarms… Concentration alarm setup… Measure Back… ClrAlmRange Begin Ppm RangesRanges… Begin / end of ranges…Measurement display configuration… Measurement Display ConfigurationLinearization Gas concentration units Concentration MeasurementGas measurement units Concentration measurement…Ppm to mg/Nm3 conversion factor Temperature compensation at span gasSensor model Clamp low PVA toFlow measurement… Flow MeasurementFlow lower limit 400 ml/min Temperature measurement… Measure Status… Back… Temperature MeasurementTemperature measurement units System SIO module… System & Network I/O Module CON Trols SetupSystem & network I/O module controls… 37.50 ppmSystem SIO Analog output setup…Choose the analyzer module Analog Output SetupChoose signal Select analog output numberHold output during calibration Signal value for 0% outputHold output during calibration Outputs value on analyzer failure Operation modeOutput number Baud rate 19200 Analog Output Updates Per SecondType of installed serial inter- face Output #1 YesChoose source module Relay Outputs SetupInvert signal Communication protocolInput number Choose signal…System DIO Function controlSystem Configuration and DIAG- Nostics Load/Save Module Configura- tion Diagnostic MenusAnalyzer Module Diagnostics Security Codes Date and TimeSystem reset Measure Back… System ResetEntering a level locked by security code Model NGA 2000 TO2 Overview Electrical Shock Hazard Section Maintenance and ServiceSensor Caustic Liquid Refilling Sensor Sensor AssemblySensor Replacement Electrolyte ReplacementSensor Lleak Check Time & Date Analyzer and I/O expert controls & setup…Linearization Do not tilt Sensor excessively as elec- trolyte may leakLinearization raw values sensor current… Linearization temperature values…Linearization… 0000 ppmPrinted Circuit Boards Flow Sensor ReplacementElectronic Components FusesErratic and very insensitive readings Section TroubleshootingTroubleshooting Failure to purge down to ppm levelsModel NGA 2000 TO2 Matrix Section Replacement PartsTO2 NGA 2000 TO2 Trace Oxygen Analyzer Module Replacement Parts Training Customer ServiceSection Return of Material Return of MaterialModel NGA 2000 TO2 Section Index Model NGA 2000 TO2 Product ELECTROLYTE1 Threshold limit value Routes of entry Emergency & first aid proceduresPrecautions to be taken in handling Other precautionsRosemount Warranty Asia Pacific EUROPE, Middle EAST, Africa Latin America
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