GDS Corp GASMAX CX User manual

GDS Corp.
1245 Butler Road League City, TX 77573
409-927-2980 409-927-4180 (Fax) ww.gdscorp.com
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Operation and Maintenance
Manual
GASMAX CX + GDS-IR
GASMAX CX Gas Monitor with GDS-IR Infrared Sensor for
Combustibles and Carbon Dioxide

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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CAUTION: FOR SAFETY REASONS THIS EQUIPMENT MUST BE OPERATED AND
SERVICED BY QUALIFIED PERSONNEL ONLY. READ AND UNDERSTAND
INSTRUCTION MANUAL COMPLETELY BEFORE OPERATING OR SERVICING.
ATTENTION: POUR DES RAISONS DE SÉCURITÉ, CET ÉQUIPEMENT DOIT
ÊTRE UTILISÉ, ENTRETENU ET RÉPARÉ UNIQUEMENT PAR UN PERSONNEL
QUALIFIÉ. ÉTUDIER LE MANUE D’INSTRUCTIONS EN ENTIER AVANT
D’UTILISER, D’ENTRETENIR OU DE RÉPARER L’ÉQUIPEMENT.
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REVISION HISTORY
Revision 1.0 2/15/17 Initial Release
Copyright © 2017 GDS Corp. All Rights Reserved
P/N 1200-0934-01

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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Page 3
CONTENTS
1SAFETYINFORMATION_______________________________________________5
2OVERVIEW_________________________________________________________6
3INSTALLATION______________________________________________________7
4INITIALSTARTUP___________________________________________________12
5CALIBRATION______________________________________________________16
6MAINTENANCE_____________________________________________________19
7TROUBLESHOOTING_________________________________________________21
8SPECIFICATIONS____________________________________________________23
9SPAREPARTS______________________________________________________24
10DRAWINGSANDDIMENSIONS______________________________________25
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GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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TABLEOFFIGURES
FIGURE2‐1:GASMAXCX+GDS‐IRLOCALSENSOR........................................................................................6
FIGURE2‐2:GASMAXCX+GDS‐IRREMOTESENSOR.....................................................................................6
FIGURE3‐1:GASMAXCXI/OPOWER&SIGNALWIRING...............................................................................8
FIGURE3‐2:GASMAXCXETHERNETINTERFACE............................................................................................9
FIGURE3‐3GASMAXCXOPTIONALRELAY/MODBUSINTERFACE................................................................9
FIGURE3‐4:GASMAXCX+GDS‐IRLOCALSENSORWIRINGDIAGRAM........................................................10
FIGURE3‐5:GASMAXCX+GDS‐IRREMOTESENSORWIRINGDIAGRAM....................................................10
FIGURE3‐6:MODBUSWIRINGJUNCTIONBOX............................................................................................11
FIGURE3‐7:MODBUSJBOXLOCATIONOPTIONS........................................................................................11
FIGURE4‐1:GASMAXSINGLECHANNELDISPLAY........................................................................................12
FIGURE4‐2:GASMAXDUALCHANNELDISPLAY...........................................................................................12
FIGURE4‐3:USERMENUSCREEN.................................................................................................................13
FIGURE4‐4:ACCESSINGCALMODE.............................................................................................................13
FIGURE4‐5:GASMAXDATADISPLAY...........................................................................................................14
FIGURE4‐6:GASMAXTRENDDISPLAY.........................................................................................................14
FIGURE5‐1:CALIBRATIONFLOWCHART......................................................................................................16
FIGURE5‐2:CALIBRATIONSETUP.................................................................................................................17
FIGURE5‐3:IRZEROFORLOCALSENSORS...................................................................................................18
FIGURE5‐4:IRZEROFORREMOTESENSORS...............................................................................................18
FIGURE6‐1:GDS‐IRDISASSEMBLY...............................................................................................................20
FIGURE9‐1:GASMAXCX+GDS‐IRLOCALSENSORSPAREPARTS................................................................24
FIGURE10‐1GASMAXCX+GDS‐IRDIMENSIONS(VERTICAL)......................................................................25
FIGURE10‐2GASMAXCX+GDS‐IRDIMENSIONS(HORIZONTAL)................................................................26

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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Page 5
1SAFETYINFORMATION
Important–ReadBeforeInstallation
UsersshouldhaveadetailedunderstandingofGASMAXCXoperatingandmaintenanceinstructions.Use
theGASMAXCXonlyasspecifiedinthismanualordetectionofgasesandtheresultingprotection
providedmaybeimpaired.ReadthefollowingWARNINGSpriortouse.
WARNINGS
CAUTION:KEEPEXPLOSIONPROOFCOVERTIGHTWHILECIRCUITSAREALIVE
MISEENGARDE:GARDEREXPLOSIONCOUVERTUREPREUVETIGHTCIRCUITSPENDANTQUESONT
ALIVE
Unitmustbeinstalled,operatedandmaintainedinaccordancewithinformationcontainedherein.
Installationinanyhazardousareamustcomplywithallapplicablerestrictions,requirementsand
guidelinesforsaidhazardousareas.Itistheendusercustomer’sfinaldecisiontoensurethatthe
GASMAXCXissuitablefortheintendeduse.
TheGASMAXCX+GDS‐IRisdesignedandconstructedtomeasurethelevelofcertaingasesin
ambientair.Accuracyinatmospherescontainingsteamorinertgasescannotbeguaranteed.
TheGDS‐IRinfraredsensormaybemountedverticallyorhorizontally.DonotmounttheGDS‐IR
upsidedown.IfusingtheGDSRainShield[IRRS],thesensormustbemountedhorizontally.
Donotpainttransmitterorsensorassembly.
DonotoperatetheGASMAXCX+GDS‐IRiftheenclosureisdamagedorcrackedorhasmissing
components.Makesurethecover,internalPCB’sandfieldwiringaresecurelyinplacebefore
applyingpower.
DonotexposetheGASMAXCX+GDS‐IRtoelectricalshockorcontinuousseveremechanicalshock.
ProtecttheGASMAXCX+GDS‐IRandrelatedsensorassembliesfromdrippingliquidsandhighpower
sprays.
Calibratewithknowntargetgasatstart‐upandcheckonaregularschedule,atleastevery90days.
Morefrequentinspectionsareencouragedtospotproblemssuchasdirt,oil,paint,greaseorother
foreignmaterialsonthesensorhead.
Periodicallytestforcorrectoperationofthesystem’salarmeventsbyexposingthemonitortoa
targetedgasconcentrationabovetheHighAlarmsetpoint.
Useonlyforapplicationsdescribedwithinthismanual

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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2OVERVIEW
TheGASMAXCXisanext‐generationsingleordualchannelfixed‐pointgasmonitordesignedtoprovide
continuousmonitoringoftoxicorcombustiblegasesinhazardousareas.Gasvaluesaredisplayedin
calibratedengineeringunitsonahighlyvisiblecolorLCDdisplay.TheGDS‐IRisahighperformancegas
sensorthatusesinfraredtechnologytodetectthepresenceofcombustiblehydrocarbongases.
TheGASMAXCX+GDS‐IRcombinationisavailableinbothLocalSensorandRemoteSensorconfigurations
asshownbelow:
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Figure 2-1: GASMAX CX + GDS-IR Local Sensor
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Figure 2-2: GASMAX CX + GDS-IR Remote Sensor
TheGASMAXCXisenclosedinaCSA/FM/IECExcertifiedanodizedaluminumexplosionproofyellow
enclosuredesignedtoprotecttheelectronicsandmakeiteasyforworkerstoidentifyinindustrial
environments.Thescrew‐onfrontcoveriseasilyremovedforinstallationandmaintenance;however,
built‐inuserinterfacemagneticswitchesallowoperatorsandtechnicianstoadjust,calibrateor
troubleshoottheGASMAXCXwithoutdeclassifyingthearea.
SeetheGASMAXCXUser’sManualformoreinformationontheGASMAXCXgasmonitor.
GDS‐IRRainShield
Vertical
Configuration
Horizontal
Configuration
GASMAXCX
GasMonitor
LocalGDS‐IR
InfraredSensor
GASMAXCX
GasMonitorRemoteGDS‐IR
InfraredSensor
RemoteGDS‐IR
InfraredSensor
withRainShield

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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3INSTALLATION
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SELECTINGALOCATION
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Factorssuchasprevailingwinds,targetgasdensity,potentialleaksources,airmovementmachineryand
similarenvironmentalvariablesareimportantwhenselectingalocationfortheGASMAXCX+GDS‐IRgas
monitororgassensor.EventhoughtheGASMAXCX+GDS‐IRisdesignedforruggedservice,sensorsand
electronicsshouldbeprotectedfromenvironmentaldamageduetowater,snow,shock,vibrationand
dirt.Inaddition,thesensorand/ordisplayshouldbelocatedsuchthatregularmaintenanceandperiodic
sensorreplacementcanbereadilyaccomplished.Whiletherearenoindustrystandardsforgasdetector
placement,professionaltoolsexistthatcansimulateleaksorspillsandprovideexcellentguidancefor
locatinggasdetectorsthroughoutafacility.
INSTALLATION
GASMAXCXmonitorswithGDS‐IRsensorsarecertifiedforuseinClass1Division1hazardousareas.
Installationintheseareasshouldfollowbestindustrystandardpracticesandallappropriateelectrical
codes.Generally,thesecodesrequirerigidmetalconduit,pouredsealsandotherinstallationelements
necessarytoensuresafety.
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FormaximumprotectionagainstRFinterferenceorelectricalsurge,theGASMAXCXenclosure,allremote
sensorsandinterconnectingconduitmustbeproperlygrounded.
INTRINSICALLYSAFEINSTALLATION
TheGASMAXCXisnotcertifiedforuseasanIntrinsicallySafedevice.
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MOUNTINGTHEGASMAXCXINSTRUMENTENCLOSURE
TheGASMAXCXstandardenclosureisacastaluminumexplosion‐proof(NEMA7)enclosure.Twochannel
GASMAXCXunitswithduallocalsensorheadsincludea“Y”adapter.TheGASMAXCXorremotesensor
shouldalwaysbemountedwiththesensorheadopeningfacingdown.
WheninstallingtheGASMAXCX+GDS‐IR,leaveaminimum
of12inchesofclearancebelowthesensorforvertical
configurationsand12”belowand12”totherightof
horizontalconfigurationstoallowforgasflowandremoval
ofthestainlesssteelbarrelformaintenanceandcleaning.
12”MIN
12”MIN
12”MIN

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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CONNECTINGDCPOWER&OUTPUTSIGNALWIRING
ToaccesstheGASMAXsignalandpowerconnections,removethecoverontheGASMAXCXexplosion‐
proofenclosure,loosenthe2thumbscrewsholdingthedisplayassemblyandremoveit.Thedisplaywill
remainconnectedtotheIO/PowerSupplyPCBmountedinthebackoftheenclosurebyashortribbon
cable.
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Figure 3-1: GASMAX CX I/O Power & Signal Wiring
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Routethepowerandsignalwiresthroughtheconduitentryandconnecttoterminalblock“TB1”.
Plus24VDCconnectstoTB1‐1.DCGroundconnectstoTB1‐4.ChannelOne4‐20mAoutputisavailableon
TB1‐2andChannelTwo4‐20mAoutputisavailableonTB1‐3.
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GDSCorpalwaysrecommendsusingshieldedwireforsignalandpowercable.
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CONNECTINGTOANETHERNETNETWORK
TheGASMAXCXprovidesastandard10/100EthernetnetworkinterfaceonthePowerI/Oboardas
showninFig.4‐2.BothDHCPandfixedIPaddressmodesareprovided.TheEthernetinterfaceprovides
accesstotheMODBUSdatabaseviaMODBUS/TCPaswellasremoteaccessandsetupviaabuilt‐inweb
server.




COM
420OUT2
420OUT1
PWR
R/PWR
C/420IN1
A/COM
420IN2
CH1CH2
E‐NET
LOCAL
SENSOR
TO DISPLAY
TB1
–
1:+12‐30VDCInput
TB1–2:Channel14‐20mAOut
TB1–3:Channel24‐20mAOut
TB1–4:Power/SignalCommon
NOTE:THEMAXIMUMDISTANCE4‐20MASIGNALSCANTRAVELISDEPENDENTUPONCABLE
GAUGE,DCPOWERSUPPLYVOLTAGELEVELANDINPUTIMPEDANCEOFTHERECEIVINGDEVICE.
ASSUMINGANOMINAL24VDCPOWERSUPPLY,100OHMLOADANDMAXIMUMTOTALLOOP
RESISTANCEOF750OHMS:
#18GA,0.0064OHM/FT=>9.6MILES/15.5KM
#24GA,0.026OHMS/FT=>2.3MILES/3.7KM
Note:
LocalGDS‐IRoutputisonChannel2
RemoteGDS‐IRoutputcanbeconfigured
foreitherchannel.

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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Page 9
CONNECTINGETHERNETSIGNALWIRING
TheGASMAXCXprovidesastandardRJ‐45EthernetconnectoronthecenteroftheIO/PowerSupplyPCB.
DatacanbeaccessedusingtheMODBUS/TCPdataprotocolorviathebuilt‐inwebpage.SeeGASMAXCX
manualformoredetails.

Figure 3-2: GASMAX CX Ethernet Interface

OPTIONALRELAY/MODBUSINTERFACE
TheoptionalRelay/Modbusboardisconnected“piggyback”tothebackoftheGASMAXCXDisplay
Assemblyandprovidesthreelevelalarmrelays,aFAULTrelay(“K3”),twoRS‐485ModbusRTUserialports
andaccesstotheDigitalInput/RemoteACKport.


Figure 3-3 GASMAX CX Optional Relay / MODBUS Interface

NOTE:THEFAULTRELAYISPROGRAMMEDTOOPERATEINFAILSAFEMODEONLY;THERELAYISACTIVE
WHENNOFAULTEXISTS(C‐>NO),ANDBECOMESINACTIVEIFAFAULTISPRESENT(C‐>NC).

COM
420OUT2
420OUT1
PWR
R/PWR
C/420IN1
A/COM
420IN2
CH1CH2
E‐NET
LOCAL
SENSOR
TO DISPLAY
2
3
4
1
TB1
5
B
S
A
A
B
TB2
RelayWiring:
1Fault1NC
2Fault1Common
3Fault1NO
4Relay3NC
5Relay3Common
6Relay3NO
7Relay2NC
8Relay2Common
9Relay2NO
10 Relay1NC
11 Relay1Common
12 Rela
y
1NO
MODBUSinterface
ModbusWiring:
1Modbus1A
2Modbus1B
3ShieldTiePoint
4Modbus2A
5Modbus2B
RemoteAlarmAcknowledge
S1
–
Ethernet
RJ‐45Connector
NOTE:USERMENUCHANGESTO
NETWORKSETUPPARAMETERS
REQUIRESADEVICEREBOOT.
NOTE:STANDARDETHERNET
CABLESWITHMOLDEDSTRAIN
RELIEFFITTINGSARENOT
RECOMMENDEDDUETOSPACE
CONSTRAINTS.

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
Page 10
LOCALGDS‐IRSENSORWIRING
AGASMAXCXwithlocalGDS‐IRsensorispre‐wiredatthefactoryasshownbelow.TheGASMAXCX
includesasensorpersonalityboardthatadaptstheGDS‐IRwiringtotheGASMAXCXinputsandprovides
amagneticswitchthatallowstheusertoperformthe“IRZero”functionwithoutopeningtheenclosure.


Figure 3-4: GASMAX CX + GDS-IR Local Sensor Wiring Diagram

REMOTEGDS‐IRSENSORWIRING
WiringbetweentheGASMAXCXandaremoteGDS‐IRsensorisprovidedbythecustomer.Theinterface
requiresafour‐conductorshieldedcableasshownbelow.Theremotejunctionboxprovidesbotha
magneticswitchandlocalpushbuttonforthe“IRZero”function.


Figure 3-5: GASMAX CX + GDS-IR Remote Sensor Wiring Diagram

COM
420OUT2
420OUT1
PWR
R/PWR
C/420IN1
A/COM
420IN2
CH1CH2
E‐NET
LOCAL
SENSOR
TODISPLAY
BlackWire–CommonGround
BlueWire–Sensor4‐20mAOutput
WhiteWire‐IRZeroInput
RedWire‐+18to+30VDCInput
Important–RemoveDCpowerbeforeconnectingor
disconnectinganywiringto/fromtheGDS‐IR
Sensor
Personality
Board
Sensor
Personality
Board
Remote
GDS‐IR
Sensor
Remote
Sensor
Junction
Box

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0

Page 11
+24 GND A
+24 GND A
PWRto
MODBUSto
+24
GND
“
A
”
“B”
+24
GND
“
A
”
“B”
OPTIONALMODBUSWIRINGJUNCTIONBOX
MODBUSsystemarchitecturerequiresthatthedevicesinanyMODBUSloopbeconnectedinadaisy‐
chainlayout.Thisminimizessignalreflectionsandimprovessignalnoisemargin.AMODBUSTermination
JumperinstallsaloadresistoracrosstheMODBUSsignallinesandshouldonlybesetto“A”(ON)atthe
lastdeviceinthestring.
CableselectionforMODBUSsystemsisimportantforbothsignalintegrityandpowerdistribution.
MODBUS/RS‐485transmissionsuselow‐voltagedifferentialsignalingtoachievereasonabledatarates
oververylongdistances,upto4000feetwithoutarepeater.For
MODBUSdatasignals,GDSCorprecommends20GAto24GAtwisted
shieldedcable.Daisy‐chainpowerdistributionmayrequirelarger
gaugewiresinceitiscriticalthatthesupplyvoltagefortheGASMAX
CXatthefarendofthestringnotfallbelow12VDCduringpower‐up.
NotethatwhiletheGASMAXCXhastwosetsofwiringterminalsfor
MODBUS“A”and“B”signals,daisy‐chainpowerwiringrequiresthat
twowiresbeinstalledinthe“+24”and“GND”terminalsonthe
GASMAXCXI/OPowerSupplyboard.Thiscanbedifficultifwiresizes
arelargerthan#18GA.Forthesereasons,ifMODBUSisrequiredGDS
CorprecommendstheadditionoftheMODBUSWiringJunctionBox
(seeFig.5‐7).Thisoptionminimizestheneedtoaccesswiringinside
theGASMAXCX,providesindividualwirelandingpointsforincoming
andoutgoingMODBUSandpowerwiringandshields,andmakesit
easytotemporarilydisconnecttheGASMAXCXpowerorMODBUS
connectionswithoutaffectinganyotherMODBUSdevice.
TheMODBUSwiringjunctionboxisattachedtotheGASMAXCX,
eitheronthebottomfittingoroneofthesidefittings,dependingon
installationrequirements.SpecifyBOTTOM,TOP,LSIDEorRSIDEwhen
ordering(Seebelow).


Figure 3-7: MODBUS JBOX LOCATION OPTIONS

Figure 3-6: MODBUS Wiring
Junction Box
“TOP”
“RSIDE”

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
Page 12
4INITIALSTARTUP

WhenpowerisappliedtotheGASMAXCX,thescreenwillshow‘GASMAXCX”followedbyoneortwo
SmartSensorinformationscreensifthesensor(s)arelocallyconnected.Certainsensorsmayinitially
indicateoff‐scalehighorlowvalues,butshouldquicklyreturntozerowithinafewminutesifnotarget
gasispresent.Duringthiswarm‐updelayperiod,the4‐20mAoutputisheldat4.0mAtoeliminatefalse
alarmsinanyreceivingdevices.
GASMAXUSERINTERFACE
TheGASMAXCXdisplayisshowninFigure5‐1.Therearefourmagneticswitchesonthefaceofthe
GASMAXCX,arrangedinaquadrantaroundtheLCDdisplay;thesearelabeledNEXT,EDIT,DOWN/CAL
andUP.Toactivate,or“press”amagneticswitch,swipethemagneticwandneartheswitch.Forthe
balanceofthismanual,theterm“press”willbeusedtodescribeactivationofanykeyviathemagnetic
wand.

Figure 4-1: Gasmax Single Channel Display

PressingtheNEXTkeycausestheGASMAXdisplaytoswitchdisplayscreens.Insinglechannelmode,the
displaywillswitchbetweenDATAandTREND.Indualchannelsystems,thesequencewillbe:DATA1,
DATA2,TREND1,TREND2,DUALCHANNEL,followedbyDATA1.

Figure 4-2: Gasmax Dual Channel Display


GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0

Page 13
PresstheEDITkeytoaccesstheUSERMENUdisplaymode.Wheninusermenudisplaymode,useUP
andDOWNtoselectanitem,EDITtochangeanitem,andNEXTtoexitthemenuorfunctionandreturn
theGASMAXCXtodisplaymode.SeeChapter8formoreinformationonUserMenus.

Figure 4-3: User Menu Screen
NOTE:TAKECAREWHENCHANGINGGASMAXMENUSETTINGS–INCORRECTSETTINGSCOULDCAUSE
THEGASMAXTOBECOMEINOPERATIVEANDMAYCOMPROMISETHESAFETYOFTHEGASDETECTION
SYSTEM.BESURETOUNDERSTANDWHATTOCHANGEANDWHYBEFOREENTERINGTHEUSERMENU.
PresstheDN/CALkey,followedbytheEDITkey,toaccessCALIBRATIONMODE.Regularcalibrationis
criticallyimportanttothecontinuedsafeoperationofanygasdetectionsystem.SeeChapter6formore
informationoncalibration.

Figure 4-4: Accessing Cal Mode
NOTE:TAKECAREWHENAPPLYINGCALIBRATIONGASTOTHEGASMAXWHILENOTINCALIBRATION
MODE.THISWILLCAUSEANINCREASEINTHE4‐20MAOUTPUTSIGNALANDMAYRESULTIN
UNINTENDEDANDUNEXPECTEDALARMCONDITIONS.

ToaccessCal
Mode,pressthe
DN/CALkeyfirst
ThenpresstheEDIT
keytoconfirm
CalibrationMode

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
Page 14
MOREINFORMATIONONDISPLAYSCREENS
TheDATAdisplayscreenshowsasinglechannel’sinformation.Thecurrentvalueisshownincalibrated
engineeringunits.AhorizontalbargraphtracksthecurrentvalueandshowstheAlarm1andAlarm2
valuesingraphicalform.Theuser‐programmableEngineeringUnits(“Eunits”)andMeasurementName
textstringsareshownbelowthereal‐timereading.
AbovetheLCDdisplay,threeLEDsindicatethestatusofthelevelandfaultalarms.Ifrelaysareinstalled,
theLEDsindicatewhethertherelaysareactive.NotethatifanyrelayissetforFAILSAFEoperation,ifLED
isONtherelaywillbede‐energized.Indualchannelmode,ifeitherchannelisinalarmthecorresponding
A1orA2indicatorLED(andrelay)willbeenergized.

Figure 4-5: GASMAX Data Display
TwoLEDsmonitortheMODBUSRS‐485transmit(TXD)andreceive(RXD)buffers.Flashingindicatessent
orreceiveddata.RXDwillflashwheneveramessagefromtheMODBUSmasterisreceivedandTXDwill
flashwhenanyresponsemessageistransmittedfromtheGASMAX.


Figure 4-6: GASMAX Trend Display

TheTRENDscreendisplaysagraphwiththelast30minutesoflivereadings.TheEUNITSvalueisshownat
thetopandAlarm1andAlarm2levelsareshownasdotted(A1)anddashed(A2)lines.

EngineeringUnitsValue
HorizontalBargraph
AlarmLevels
“MeasurementName”
MODBUSCommunicationsLEDs
EngineeringUnits
30MinuteTrend
Alarm2Level(RED)
Alarm1Level
(
YELLOW
)


GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0

Page 15
ALARMSETUP–ALARM1,2AND3
Eachchannelcanbeprogrammedforuptothreeindependentalarmlevels,andcanbesettoalarm
ABOVEthetargetvalueforBELOWthetargetvalue.Allprogrammingisdoneinengineeringunitsthat
correspondtothechannelsZEROandSPANsettings.Alarmprocessingwilltriggeranalarmcondition
whentheinputexceedstheprogrammedvalue,andincludeshysteresistokeepthealarmfromrapidly
switchingONandOFFiftheinputremainsclosetotheprogrammedalarmvalue.
NOTE:ALARMRELAYSARENORMALLYTRIGGEREDIFEITHERCHANNEL1ORCHANNEL2ALARM
THRESHOLDSAREEXCEEDED.
NOTE:IFTHEOPTIONALALARMRELAYSARENOTINSTALLED,ALARMSETTINGSAFFECTTHEOPERATION
OFTHEFRONTPANELDISPLAYONLY.SEPARATEALARMSETTINGSMAYNEEDTOBEPROGRAMMEDIN
THE4‐20MARECEIVINGDEVICE.
ALARMOPERATION–FAULT
FAULTistypicallyusedtoindicateFAULTconditionsthatsuggestsensorfailureor“outofmeasurement
range”conditions.

SYSTEMSETUP
Onceoperational,theusershouldverifythefollowingsettingspriortoinitialcalibration:
1. Localtimeanddate:Checkdatevalueandadjusttimeforpropertimezone.
2. TagnameorEngineeringUnitssettings:Editvaluesasnecessary.
3. CALSPANGASvalue:Settomatchconcentrationofcalibrationgascylinder.
4. CALMARKERvalue:AdjustdesiredoutputmAduringcalibration.
5. ALARM1,ALARM2,ALARM3settings:Setfordesiredlevels.NOTE:Ifrelaysarenotinstalled,
GASMAXCXprogrammablealarmlevelsaffectoperationofdisplaycoloronly(Sec7‐3).


GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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5CALIBRATION

CALIBRATIONOVERVIEW
CalibrationiscriticallyimportanttoensurecorrectoperationoftheGASMAXCX.Thebuilt‐inCALMODE
functionisdesignedtomakecalibrationquick,easyanderrorfree;asuccessfulZEROandSPAN
calibrationfortheGASMAXCXrequiresonlyfourkeystrokes.
DuringCALMODEzeroandspan,thesensoroutputisdisconnectedandtheGASMAXCXtransmitsafixed
mAvalue,calledtheCALMARKER,tonotifythereceivingdevicethatacalibrationisinprogress.During
thefollowingCALPURGEDELAYtime,theGASMAXCXtransmitsafixed4.0mAsignaltopreventexternal
alarmsduringcalibration.
Alwaysfollowthesegeneralcalibrationguidelines:
Calibrationaccuracyisonlyasgoodasthecalibrationgasaccuracy.GDSCorpcalibrationgasesare
traceabletoNIST(NationalInstituteofStandardsandTechnology).
Neverusecalibrationgasthathaspasseditsexpirationdate.
ChecktheSPANGASVALUEsettingandmakesureitmatchesthecalibrationgasvalue.
AlwaysuseaGDSCorpcalibrationcuporwrapthatcompletelysurroundsthesensorhead.
BesuretouseZEROAIR,amixtureof21%oxygenand79%nitrogen,asazeroreferenceunlessyou
arecertainthatnotargetgasexistsinthearea.Ambientgasmayresultinan‘elevatedzero’
conditionthatwillcauseaFAULTtooccuroncetheambientgasisnolongerpresent.
Alwayscalibrateanewsensorbeforedependingonthedeviceforpersonnelorequipmentsafety
Calibrateonaregularschedule.GDSCorprecommendsafullcalibrationevery3months,with
periodic‘bumptests’onamorefrequentbasistoensurethatthesensorhasnotbeenaffectedby
temperatureextremesorthepresenceofincompatiblegases.

TheflowchartshowninFigure5‐1illustratestheaboveprocedure.UP,CAL,NEXT&EDITlabelsindicate
keystrokesusingthemagneticwand.ZEROorSPANcalibrationwillfailifthereadingsexceedbuilt‐in
limitsformaximumallowablezeroorminimumallowablespan.

Figure 5-1: Calibration Flowchart

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0

Page 17
CALIBRATIONPROCEDURE 
TheGDS‐IRinfraredsensorishighlystableandshouldnotrequirecalibrationmorethanonceeverysix
monthsundernormalconditions.However,eachinstallationisuniqueandGDSCorprecommends
performingacalibrationuponinitialstartupandwithin3months.
Allowatleast30minutesfrominitialpower‐upforthesensortostabilizebeforebeginningany
calibrationprocedure!
Beforebeginningcalibration,makesureyouhavethefollowingitems:
1. Cylinderofcalibrationgaswithfixedflowregulator(1.0LPMisrecommended)
2. Cylinderof‘zeroair’forzeroreferenceandspangaspurge(ifneeded)
3. 3’lengthofflexibletubing
4. GDS‐IRcalibrationwrapaccessory(p/n20‐0243)



Figure 5-2: Calibration Setup

STEPONE–GDS‐IRZERO 
1. Connectthecylinderofzeroairtothefixedflowregulator,andconnectthetubingtothecalibration
portonthebottomoftheGDS‐IRsensor.
2. InstalltheGDS‐IRcalibrationwrapaccessoryaroundtheGDS‐IRtoblockthesensor’sgasaccess
holes.
3. Turnontheregulatorandallowgastorunfor30seconds.
4. Localsensor:UsethemagneticwandtotriggertheIRZeroreedswitchlocatedontherightsideof
theSensorPersonalityBoard.Remotesensor:UsethemagneticwandtotriggertheIRZeroreed
switchlocatedontherightsideoftheSensorJunctionBoxboardorpresstheGDS‐IRZerobuttonon
theSensorJunctionBoxboard.Pressoractivatethebuttonorswitchfor10seconds.Ifsuccessful,the
GASMAXCXDisplaywillshowthemessage“IRZERO”.(SeediagramonnextpageforIRZerobutton
access).
5. Turnofftheflowofzeroair.TheIRZerofunctionisnowcomplete.


CylinderofSpanGasor
ZeroAir
Regulator
Flexible
Tubing

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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
Figure 5-3: IR Zero for Local Sensors




Figure 5-4: IR Zero for Remote Sensors

STEPTWO–GASMAXCXCALIBRATION
1. PresstheNEXTkeyuntilthattheDATADisplayforthedesiredchannelisshown.
2. ToenterCALMODE,presstheDOWN/CALkeyandwithin5secondspresstheEDITkey.
3. ThescreenwilldisplayanAPPLYZEROmessage.Turnontheregulatorandwait30seconds.Pressthe
EDITkeytocompletethezeromeasurement.
4. IftheZEROCALSUCCESSFULmessageisdisplayed,anAPPLYSPANmessagewillappear.Removethe
cylinderofzeroairandconnectthecylinderofspangas.Doublechecktheconcentrationand
expirationdate.Thereadingwillincreaseasthespangasflowsintothesensor.
5. Afterthereadingisstable,(approximately1minute)presstheEDITkeytocompletetheSPANGAS
calibration.IftheSPANcalibrationissuccessful,thedisplayflashesREMOVECALGASandstartsthe
CALPURGEdelay.
6. Immediatelyshutofftheregulatorandremovethecalibrationwrap.AttheendoftheCALPURGE
delay,theGASMAXCXoutputisre‐enabledandtheunitisfullyoperational.

IRZeroButton
IRZeroMagSwitch
IRZero
Mag
Switch
IRZero
Mag
Switch
IRZeroButton
GASMAXCX
RemoteGDS‐IRSensorscanbe
zero’dfromeithertheGASMAXCX
orremoteSensorJunctionBox
LocalGDS‐IRSensorsarezero’d
byplacingamagneticwand
immediatelynexttotheright
sideoftheexplosionproof
enclosureasshownatright

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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6MAINTENANCE
GASMAXCX
NormalmaintenancefortheGASMAXCXprimarilyinvolvesperiodiccalibrationonstandardintervals.GDS
Corprecommendscalibrationatleasteverythreemonths,ormoreofteniftemperatureextremes,
vibration,thepresenceofincompatiblegasesorotherenvironmentalfactorsmayacceleratethe
deteriorationofthesensorelement.Calibrationshouldalsoincludeinspectionsforcloggedorwetsensor
heads,crackedordamagedenclosuresandwaterincursioninsideconduitorjunctionboxes.
GDS‐IRINFRAREDSENSOR
WhenpowerisappliedtotheGDS‐IR,itentersaone‐minutewarm‐upperiod.Theoutputcurrentwillbe
0.8mAduringthewarmuptimeperiod.Attheendofthewarm‐upperiodwithnofaultspresent,the
GDS‐IRautomaticallyentersnormaloperatingmodeandoutputs4.0mA.Ifafaultispresentafterwarm‐
up,thedetectorcurrentoutputwillindicateafault.
Inthenormaloperatingmode,the4‐20mAsignallevel
correspondstothedetectedgasconcentration.Intheevent
ofanoverrangegasrelease,theGDS‐IRwillindicatean
overrangeconditionuptoapproximately23mA.Excessive
gaswillnotharmthesensorandtheoutputwillreturnto
normaloncethegasdissipates.Intheeventthattheinternal
microprocessordetectsafaultcondition,theoutputwillbe
settoaspecificmAreadingthatcorrespondstothetypeof
faultdetected.
TheGDS‐IRshouldbecheckedregularlyfordamage,water
ingressorhydrophobicfiltercloggingduetoexcessivedust
ordirt.Ifthehydrophobicfilterhasbecomecontaminated
bydust,dirtormoisture,unscrewthesensorheadcover,
removethesetscrewandgentlyslidethefilterdownto
remove(SeeFig.7‐1).Carefullycleanthefilterwith
compressedairandreinstall.TheGDS‐IRcanoperate
withoutthehydrophobicfilterinstallediftheatmosphere
containslittledustormoisture.Therearenouser‐
serviceablecomponents.

CLEANINGTHEGDS‐IROPTICS
Ifnecessary,theGDS‐IRcanbepartiallydisassembledtoallowcleaningoftheopticalwindowscovering
theIRsourceandIRreceiver.TodisassembletheGDS‐IR,performthefollowingsteps(Seebelow):
1. Unscrewtheoutercoverinacounter‐clockwisedirection(lookingupfromunderneath)
2. Locatethesmallsetscrewthatholdsthehydrophobicfilterinplace.Carefullyremovethescrew
usingaflat‐bladescrewdriver.
3. Gentlyslidethehydrophobicfilterdownandsetaside.
4. PlaceoneAllenwrenchintheholemarked“A”toholdthetopsectionoftheopticalwaveguidein
place.Placeanotherthroughtheholemarked“B”inthelowersectionoftheopticalwaveguide.
SensorOutput:
0.0 mA Unit Fault
0.2 mA Reference channel fault
0.4 mA Analytical channel fault
0.8 mA Unit warm up
1.0 mA Optics fault
1.2 mA Zero drift fault
1.6 mA Calibration fault
2.0 mA Unit spanning
2.2 mA Unit zeroing
4.0 mA Zero gas level (0%LEL)
5.6 mA (10%LEL)
8.0 mA (25%LEL)
12 mA (50%LEL)
16 mA (75%LEL)
20 mA Full scale (100% LEL)
20.1- 23 mA Over-range (> 100% LEL)

GASMAX CX + GDS-IR Operation & Maintenance Manual, Revision 1.0
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Usingthetwowrenches,rotatethelowersectionoftheopticalwaveguidesuchthatitscrewsinto
theuppersection.ThiswilleventuallyallowthewaveguideassemblytoberemovedfromtheGDS‐IR.
5. Usingacottonswabandalcohol,cleanthesurfacesoftheReceiverandSourceasshown.
6. ReassembletheGDS‐IR
7. Performa‘hardwarezero’oncethesensoriscompletelyreassembled.

NOTE:ITISNOTNECESSARYTOREMOVEPOWERFROMTHEGDS‐IRTOPERFORMTHISCLEANING
PROCESS.




Figure 6-1: GDS-IR Disassembly