GENERAL MONITORS Model S104

The information and technical data disclosedin this document may be used anddisseminated only for the purposes and tothe extent specifically authorized in writingby General Monitors.

Instruction Manual 04/97

General Monitors reserves the right tochange published specifications and designswithout prior notice.

Part No. MANS104Revision J/04-97

Model S104Combustible Gas

Enhanced Smart Sensor

GENERAL MONITORSModel S104

Warranty

General Monitors warrants the Model S104to be free from defects in workmanship ormaterial under normal use and service withintwo (2) years from the date of shipment. Gen-eral Monitors will repair or replace withoutcharge any such defective equipment to befound defective during the warranty period.Full determination of the nature of, and re-sponsibility for, defective or damaged equip-ment will be made by General Monitors’personnel. Defective or damaged equipmentmust be shipped prepaid to General Monitors’plant or representative from which shipmentwas made. In all cases this warranty is lim-ited to the cost of the equipment supplied byGeneral Monitors. The customer will assumeall liability for the misuse of this equipmentby its employees or other personnel.

All warranties are contingent upon proper usein the application for which the product wasintended and do not cover products whichhave been modified or repaired without Gen-eral Monitors’ approval or which have beensubjected to neglect, accident, improper in-stallation or application, or on which theoriginal identification marks have been re-moved or altered. Except for the express war-ranty stated above, General Monitorsdisclaims all warranties with regard to theproducts sold, including all implied warrantiesof merchantability and fitness and the expresswarranties stated herein are in lieu of all obli-gations or liabilities on the part of GeneralMonitors for damages including, but not lim-ited to, consequential damages arising outof/or in connection with the use or perform-ance of the product.

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Warning

The Model S104 Combustible Gas EnhancedSmart Sensor Assembly contains componentswhich can be damaged by static electricity.Special care must be taken when wiring thesystem to ensure that only the connectionpoints are touched.


Table ContentsWarrantyWarning - Electrostatic Damage

1.0 Introduction1.1 General Description1.2 Features and Benefits1.3 Applications

2.0 Sensor Assembly2.1 Sensor Signal Processing2.2 Power Supply2.3 Control Electronics

3.0 Installation3.1 Receipt of Equipment3.2 Sensor Location Considerations3.3 Installation Instructions3.4 Terminal Connections3.5 Applying Power3.6 Maintaining the X/P Integrity

4.0 Operation4.1 Calibration4.2 Digital Display Codes4.3 Fault Codes & Their Remedies

5.0 Appendix5.1 Specifications

5.1.1 System Specifications5.1.2 Electrical Specifications5.1.3 Mechanical Specifications5.1.4 Environmental Specifications

5.2 Engineering Documentation5.2.1 Termination & Outline Drawings5.2.2 Termination & Outline Drawing - CE Marked Unit

5.3 Ordering Information5.3.1 Configuration Codes5.3.2 Spare Parts and Accessories

5.4 FMRC Approval

Page Numberii

111

344

5567910

111415

171717181819192122222325

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Table of Figures

Figure 1 Combustible Gas Sensor DiagramFigure 2 Input Signal Circuit Flow DiagramFigure 3 Power Supply Circuit Flow DiagramFigure 4 Control Electronics Flow DiagramFigure 5 Overall and Mounting DimensionsFigure 6 Conduit, Drain Loop, and Seal DrawingFigure 7 Terminal ConnectionsFigure 8 Terminal Block Operation DrawingFigure 9 Wire Strip Length DiagramFigure 10 0-20mA Output Signal ConnectionsFigure 11 Input Power ConnectionsFigure 12 GMI Logo and Display Window DrawingFigure 13 Display Diagram, Automatic CalibrationFigure 14 Display Diagram, Calibration in ProgressFigure 15 Display Diagram, Calibration CompleteFigure 16 Display Diagram, Zero IndicationFigure 17 LED Flashing SequencesFigure 18 Display Diagram, Test Gas ModeFigure 19 Termination Drawing - Standard UnitFigure 20 Outline & Dimensional DrawingFigure 21 Termination Drawing - CE Marked Unit

Page Number

3344677888911111212121213192021

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1.0 Introduction

1.1 General Description

The Model S104 Enhanced Smart Sensor as-sembly is used to detect combustible gases.The microprocessor based electronics, whichare contained within an explosion proof hous-ing, process sensor input at the sensor site. Anoptional digital display provides indicationsand display codes that can be viewed througha window in the cover. An analog output sig-nal (4-20mA) provides remote and/or discreteindications of the sensor’s operation. TheModel S104 Enhanced Smart Sensor Assem-bly is rated explosion proof for use in Class I,Division 1, Group B, C, and D hazardous ar-eas.

1.2 Features and Benefits

Microprocessor Based Electronics: monitors9 individual fault conditions, processing inputsignals from the sensor and providing outputsin the form of LED flashing sequences, dis-play codes, and an analog output signal.

One Person Calibration: initiate the calibra-tion sequence with a magnet, apply the gas,and wait for the LED switch or optional dis-play to indicate that the unit has completed thecalibration. No tools or adjustments are re-quired.

2 Digit Display: (optional) indicates gas con-centrations, fault codes, and calibration cues.

4 to 20 mA Output: transmits fault, calibra-tion, and gas concentrations to a remote dis-play, computer or other device.

1.3 Applications

This is a partial listing of applications.

l Drilling and Production Platformsl Fuel Loading Facilitiesl Compressor Stationsl Oil Well Loggingl LNG/LPG Processing and Storagel Waste Water Treatmentl Gas Turbinesl Solvent Vaporsl Hydrogen Storage

1GENERAL MONITORSModel S104

2.0 Sensor Assembly

2.1 Sensor Signal Processing

General Monitors uses a low temperaturecatalytic bead to detect the presence of com-bustible gases. Combustible gases are foundin many gases and vapors. The catalytic beadconverts the combustible gas to heat. Achange in heat is converted to a change in re-sistance.

By taking a matched pair of catalytic beadsand coating one so that it does not respond tothe presence of combustible gases, we cancompare the change in resistance between thetwo beads. The bead that is coated is calledthe reference bead and the other is called theactive bead (figure 1). Environmental factorscan also influence the temperature of the cata-lytic beads. Because the beads are a matchedpair, they will respond to changes in ambienttemperature, humidity, and pressure equally.

figure 1

By connecting one end of each catalytic beadtogether, a series circuit is formed. This cir-cuit is supplied with a constant voltage. Thevoltage drop across each of the beads will beidentical in the absence of combustible gases.As combustible material is converted to heat,the resistance of the active bead increases,causing the voltage drop across each bead tobe different. This difference is proportional tothe amount of combustible gas that is present.

The voltage from the sensor is amplified andfed to an Analog to Digital (A/D) converterand then made available to the microprocessor(figure 2).

figure 2

The baseline and the gain for the amplifier aredetermined by digital potentiometers. Theyare adjusted by the microprocessor duringcalibration.


Sensor Assembly

2.2 Power Supply

The Model S104 operates from a +24 VDC(nominal) input. This unregulated source isfed to a converter board that produces volt-ages (see figure 3). These signals are thesource for operating all of the circuitry on thecontrol and the display boards, and supplyingthe sensor with power. Terminal connectionsinside of the housing have been provided foraccepting the input power.

2.3 Control Electronics

The control electronics are centered around aneight bit microprocessor (figure 4). The Sen-sor Signal, the CAL Switch, the Non-VolatileMemory (NOVRAM), and certain Fault con-ditions are monitored as inputs. By process-ing these inputs, the following outputs aregenerated: 4-20mA Output Signal, DigitalDisplay Indications, and Calibration Values(NOVRAM). As the microprocessor (MPU)receives and processes the inputs, it deter-mines what value is output to the display, andthe 4-20mA current generator. When theCAL Switch is activated, the MPU allows theuser to choose between the Calibration or theTest Gas Modes. While the unit is in one ofthese modes, the MPU will fix the 0-20mAoutput signal to 1.5mA (0mA signal is op-tional for the calibration mode only).

Calibration Mode : When the unit is placedin this mode, the MPU accepts a ZERO valueand waits for the signal from the sensor to in-crease and then stabilize. It accepts this finalvalue as the SPAN value. These values arestored in NOVRAM and are used to adjustthe digital potentiometers associated with theInput Amplifier.

figure 3

Test Gas Mode: In this mode, the MPU willoutput the gas concentration to the displaywhile fixing the analog output at 1.5mA.When the gas concentration drops below 10%LEL, the unit will return to normal operation.The purpose of this mode is to check the re-sponse of the unit to a known level of gas anddetermine if calibration is necessary.

figure 4

4 GENERAL MONITORSModel S104

3.0 Installation

3.1 Receipt of Equipment

All equipment shipped by General Monitors ispacked in shock absorbing containers whichprovide considerable protection against physi-cal damage. The contents should be carefullyremoved and checked against the packingslip. If any damage has occurred or if there isany discrepancy in the order, notify GeneralMonitors as soon as possible. All subsequentcorrespondence with General Monitors mustspecify the equipment part and serial num-bers.

Each Model S104 is completely checked bythe factory. However, a complete check-outis necessary upon initial installation and startup to ensure system integrity.

3.2 Sensor Location Considerations

There are no standard rules for sensor place-ment since the optimum sensor location is dif-ferent for each application. The customermust evaluate conditions at the facility tomake this determination. Generally, theModel S104 Enhanced Smart Sensor shouldbe easily accessible for calibration checks.The sensor assembly should be mountedpointing down to prevent water build-up onthe sensor head. The sensor assembly shouldnot be placed where it may be coated by con-taminating substances. Although the ModelS104 is RFI resistant, it should not bemounted in close proximity to radio transmit-ters or similar equipment.

l Locate the Model S104 where prevailingair currents contain the maximumconcentration of gas.

l Locate the Model S104 near possiblesources of gas leaks.

l Observe the Model S104’s temperaturespecification and locate the unit awayfrom concentrated sources of heat.

l Sensor Assemblies should be mounted inan area that is as free from wind, dust,water, shock, and vibration as possible.See Appendix, section 5.1.4 for theenvironmental specifications of the unit.

Sensors may be adversely affected by pro-longed exposure to certain materials. Loss ofsensitivity or corrosion may be gradual if suchmaterials are present in low concentrations, orit may be rapid at high concentrations. Themore important materials adversely affectingsensors are:

l Prolonged presence of Hydrogen Sulfide(H2S) gas

l Silicones (often contained in greases andaerosols). Silicones do not chemicallyattack the sensor, they coat it and reduceor inhibit its response to the presence ofcombustible gas.

l Halides . . . compounds containingFluorine, Chlorine, Bromine, and Iodine

l Heavy metals, (e.g. Tetraethyl Lead)

The presence of poisons and contaminants inan area does not necessarily preclude the useof a Model S104 Enhanced Smart Sensor. Thefeasibility of using a sensor in such areas mustbe determined by an analysis of the specificfactors in each application and General Moni-tors should be consulted before attemptingany such installation.


InstallationSensor Location Considerations(continued)

Sensors used in these areas usually requiremore frequent calibration checks than normal,and typically have a shorter life. In manysuch applications the normal two year war-ranty would not apply.

CAUTION :General Monitors discourages the paintingof sensor assemblies. If the sensor head ispainted over, the gas will not be able to dif-fuse into the sensor. If the assembly coveris painted over, the digital display cannotbe read.

Remoting the Sensor from the Electronics:If it is necessary to remotely mount the sensorfrom the electronics and the housing, themaximum distance can be no greater than 100feet, using 14 AWG wire. Sensors that are re-motely placed must be contained in a sensorhousing (GMI P/N 10252) and the cable runmust be contained in a conduit running fromthe sensor housing to the electronics. See Ap-pendix, section 5.4.

3.3 Installation Instructions

The overall and mounting dimensions for theModel S104 (figures 5 & 20) should be usedwhen making installation determinations. Acomplete list of the mechanical specificationscan be found in the Appendix (section 5.1.3).

To prevent possible corrosion due to moistureor condensation, it is recommended that theconduit connected to the Model S104 housingbe sealed or contain a drain loop (figure 6).Each conduit run from a hazardous location toa non-hazardous location should be sealed sothat gases, vapors, and/or flames can not passbeyond the seal. The purpose of seals in aClass I hazardous location is to prevent thepassage of gases, vapors, or flames from oneelectrical installation to another through theconduit system. However, it is not required toadd a seal to the Model S104 housing tomaintain its explosion proof integrity. Spe-cific information on Class I location seals anddrainage can be found in the National ElectricCode handbook, Article 501-5.

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figure 5


InstallationInstallation Instructions (continued)

NOTE: Acetic acid will cause damage tometal components, metal hardware, ce-ramic IC’s, etc. If damage results from theuse of a sealant that outgases acetic acid(RTV silicone), the warranty will be void.

Once correctly installed, the Model S104 re-quires little or no maintenance other than peri-odic calibration checks to ensure systemintegrity. General Monitors recommends thata schedule be established and followed.

NOTE: The system’s full two year war-ranty will be voided if customer personnelor third parties damage the system duringrepair attempts.

Sensor heads exposed to the elements may re-quire the accessory mounting threads to be lu-bricated. Greasemust not be used. As analternate, PTFE (teflon) tape may be used onthreads thatdo not contact the sensor hous-ing.

The removal of particulate matter from sensoraccessories may be done through the use of anappropriate halogen-free solvent. Water orethanol are examples of suitable solvents. Theaccessories should be thoroughly dried, withcompressed air if necessary, before refitting tothe sensor body.

General Monitors recommends that the com-plete system, including all alarm circuitry, betested at least annually. Some typical items tocheck during maintenance examinations are:

l The sensor mounting, to see it is secure.

l The sensor screen, to see it is clear ofwater, oil, dust or paint which might clogit.

l The cable connections for tightness andpossible damage.

l All sensor placements, to see that they areup to date with the layout of the plant(e.g. modifications to the plant).

l The complete system, to see it has a backup supply for the full prescribed time.

3.4 Terminal Connections

The terminal blocks (TB) are located inside ofthe housing and can by accessed by removingthe cover (figure 7, CE Mark units see figure21). TB2 contains the three sensor connec-tions, White (W), Black (B), and Red (R).

figure 7figure 6


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InstallationTerminal Connections(continued)

TB1 contains the connections for Power, Re-mote Functions, and Output Signal (see figure7, CE Mark units see figure 21).

TB1 position Function

1 4-20mA Output2 Calibration Switch3 Calibration Switch4 LED5 LED6 Common (Ground)7 +24VDC Power

NOTE: Contact with PCB componentsshould be avoided to prevent damage bystatic electricity. All wire connections aremade to the Terminal Blocks.

It is recommended that three wire (red, black,white) shielded cable be used for makingpower and output signal connections on theModel S104. The terminal block accepts 16AWG to 22 AWG stranded or solid wire.Each wire should be stripped before wiringthe Model S104 Combustible Gas EnhancedSmart Sensor. To connect wiring to the ter-minal block, insert a screw driver into the or-ange tab and press down (figure 8), openingthe terminal.

figure 8

Insert the wire into the terminal and releasethe orange tab, clamping the wire in the termi-nal. Check the connection by GENTLY tug-ging the wire to ensure it is locked in.

figure 9

NOTE: 14 AWG wire can be used if it iscarefully stripped (figure 9).

A 4 to 20mA output signal is provided by theModel S104 Combustible Gas EnhancedSmart Sensor and can be sent up to 9000 feet(2740 meters) to a General Monitors read-out/relay display module, industrial analog todigital converter, computer based monitor,PLC, DCS, etc. The 4 to 20mA signal pro-vides for control room or other locations re-mote to the Model S104 to display indicationsof operation and alarm conditions.

To connect the 4 to 20mA output signal withanother unit, connect the white wire into TB1,position 1 (CE Mark units - TB3, position 1),labeled 4-20 mA OUT. For making outputsignal connections to display devices, refer tothe specific manual for that device (figure 10).

figure 10


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InstallationTerminal Connections(continued)

If a device other than a General Monitorsreadout/relay display module is being used,the commons, COM, of both systems must beconnected together. See Appendix, section5.4.

The Model S104 Enhanced Smart Sensor op-erates on a nominal power of +24 VDC. Pri-mary DC power must be provided by thecustomer unless one of the following GeneralMonitors Modules is being used with theModel S104:

l DC110 Readout/Relay Display Modulewith Power Supply & Relay Module

l DC130 Readout/Relay Display Module

l TA102A Trip Amplifier Module with aPS002

The following General Monitors Modulesprovide power connections for the ModelS104, but need a customer supplied DCsource:

l DC110 Readout/Relay Display Modulewithout Power Supply & Relay Module

l DC120 Dual Channel Display Module

l TA102A Trip Amplifier Module withouta PS002

Since the Model S104 is designed to operatecontinuously, a power switch is not includedin order to prevent accidental system shut-down.

NOTE: Power must remain disconnecteduntil all other wiring connections have beenmade.

The maximum distance between the ModelS104 and the power supply is 4500 feet (1372meters). See the Appendix (section 5.1.2) forcable length specifications. The cable runshould be as short as possible.

figure 11

To connect +24VDC to the Model S104, con-nect the red wire to TB1, position 7 (CE Markunits - TB3, position 3), labeled +24VDC.Connect the black wire to TB1, position 6(CE Mark units - TB3, position 2), labeledCOM (figure 11).

3.5 Applying Power

Before applying power to the system for thefirst time, all wiring connections should bechecked for correctness and the housing coverreplaced. Upon first power-up the sensor maytake up to fifteen minutes to stabilize.

At the initial application of power, or after afault condition, the unit will enter a fifty sec-ond Start-Up mode. During this period thedisplay will indicate an SU.


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Installation

3.6 Maintaining the X/P Integrity

The Model S104 is rated explosion proof forClass I, Division 1, Group B, C & D hazard-ous locations. Some of the factors that influ-ence the explosion proof integrity of theModel S104 Housing:

l Strength of the enclosure materiall Thickness of the enclosure wallsl Flame path between the housing and

coverl Flame path of threaded joints

The acceptable limits for explosion proofhousings that are used in Class I hazardous lo-cations are defined in CSA Standard C22.2No.30-M1986.

Anytime the cover of the smart sensor hous-ing is removed or the cover bolts are loos-ened, the flame path between the lid and thehousing is effected. If power is left on beforeloosening the cover bolts on the Model S104,it will be necessary to de-classify the area.When replacing the cover, the gap betweenthe lid and the housing should be less than.0015 inch (.038 mm). This can be verifiedby tightening the cover bolts to a torque set-ting of 50 inch-pounds or by using a feelergauge to ensure the gap between the coverand the housing is less than .0015 inch (.038mm).

There are four entry holes in the Model S104housing. These holes are dedicated for thesensor, the calibration switch and conduit.Each hole is tapped for 3/4 NPT threads. If aparticular entry hole is not used it must beplugged during operation in the field. Thefactory installs plugs for two of the entryholes.

A plastic red cap plug is placed into the re-maining hole and must be removed beforeconduit can be attached to the housing.

An S104 without a display will have the fol-lowing items placed in the remaining threeentry holes:

l A sensor, if present (if not, a plasticred cap-plug)

l A calibration switchl An aluminum housing plug

An S104 with a display will have the follow-ing items placed in the remaining three entryholes:

l A sensor, if present (if not, a plasticred cap-plug)

l Two aluminum housing plugs

The sensor, calibration switch and aluminumhousing plugs have seven threads. Each ofthese components is screwed into the housingusing five to seven turns. If it becomes neces-sary to replace one of these components, theuser must use five to seven turns to ensure theexplosion proof integrity of the housing.


4.0 Operation

4.1 Calibration

Activating the Calibration Switch will auto-matically disable the alarm circuits by sendinga 1.5mA (0mA optional) output signal. Thiswill prevent activation of the relay contactswhen using a General Monitors Readout/Re-lay Display Module with the Model S104.

General Monitors recommends that the ModelS104 Combustible Gas Enhanced Smart Sen-sor be calibrated one hour after start-up, andthat calibration be checked at least everyninety (90) days to ensure system integrity.General Monitors is not implying that the cus-tomer should expect problems with sensor lifeor stability but “frequent” calibration checksmerely ensure the integrity of the life protect-ing equipment.

The above statement is not intended to dis-courage the customer from checking calibra-tion more frequently. Frequent calibrationchecks are recommended for environmentsthat have problems such as mud collecting onthe sensor head, sensors accidentally beingpainted over, etc.

NOTE: A calibration check consists of ap-plying a known concentration of gas to thesensor and observing the reading on theModel S104, the Readout/Relay Module, orother computer data collecting systems.

General Monitors recommends that a calibra-tion schedule be established and followed. Alog book should also be kept showing calibra-tion dates and dates of sensor replacement.

Procedure with digital display:

l If it is suspected that combustible gas ispresent, it will be necessary to purge thesensor environment withZero Air. IfZero Air is not available, cover the sensorfor about thirty seconds before applyingthe calibration gas.Zero Air is air that ishydrocarbon free.

figure 12

l Place the magnet over the GMI Logo onthe cover (figure 12) of the unit and hold itthere until “AC” (figure 13) appears onthe display (about ten seconds). Allowabout five seconds for the unit to acquirethe zero reading before applying thecalibration gas. If the GMI Portable PurgeCalibrator (P/N 1400150) isnot usedwhen calibrating the Model S104 withMethane (CH4), the SPAN gas flow rateneeds to be 440cc/min to 460cc/min. SeeAppendix, section 5.4.

11

figure 13


OperationCalibration (continued)

l Apply a 50% LEL gas concentration to thesensor. The display will change from“AC” to “CP” (figure 14) indicating thatthe sensor is responding to the calibrationgas.

l After one or two minutes the display willchange from “CP” to “CC” (figure 15)indicating that the calibration is complete.

l Remove the gas and wait for the unit toreturn to normal operation. The displaywill indicate less than 5% LEL and thendrop to “0” (figure 16).

l The unit is now calibrated and the newZERO and SPAN values have been storedin the non-volatile memory.

The Model S104 can be returned to normaloperation if the magnet is re-applied ninetyseconds after initiating the calibration se-quence. If the Model S104 is placed in theCalibration Mode and no gas is applied for sixminutes, the unit will revert to a Fault condi-tion. Re-applying the magnet over the GMILogo will return the unit to the CalibrationMode.

Procedure without digital display:

See figure 17 for LED flashing sequences.

l If it is suspected that hydrocarbons arepresent, it will be necessary to purge thesensor environment withZero Air. IfZero Air is not available, cover the sensorfor about thirty seconds before applyingthe calibration gas.Zero Air is air that ishydrocarbon free.

l Place the magnet next to the end of theLED switch and hold it there until theLED comes on steady.

l Apply the calibration gas (50% LEL) andwait for the LED to blink slowly (aboutone or two minutes).

l Remove the calibration gas and allow theunit to see clean air.

l The unit is now calibrated.

figure 14

figure 15

figure 16

figure 17


OperationCalibration (continued)

Test Gas Mode(available with display only):If it is desired to check the sensor for its re-sponse without sending a gas concentrationsignal to a remote display device, this can beaccomplished by placing the Model S104 intothe “Test Gas Mode”. Procedure for checkingthe calibration:

l Place the magnet over the GMI Logo onthe cover of the Model S104. Remove themagnet when aflashing pair of bars, “--”, (see figure 18) appears on the display(about three seconds).

figure 18

l Apply the test gas to the sensor and thevalue of the gas concentration will beindicated by the flashing display in aboutone to two minutes.

l When the reading has stabilized and thetest is complete, remove the gas and theunit will return to normal operation whenthe concentration drops below 5% LEL.

The “test” gas concentration must be at least10% LEL before the unit will complete thetest sequence. If the Model S104 is placed inthe Test Gas Mode and no gas is applied forsix minutes, the unit will revert to a Fault con-dition. Re-applying the magnet over the GMILogo will return the unit to normal operation.

Calibration Equipment :ThePortable Purge Calibrator is a compact,accurate and safe system containing no explo-sive gas. The lecture bottle is filled with astandard 50% LEL mixture of gas/air. Using aknown gas/air mixture reduces the likelihoodof error in field calibration. The hose and cupadapter permits calibration without having toremove the sensor. The following pre-mixedcalibration gases at approximately 50% LELare available, in a lecture bottle, at 1200 psia,8.3 MPa maximum pressure.

l Butadienel Butanel Ethanel Hydrogenl Methanel Propane

Methane and Hydrogen lecture bottles may bereturned to General Monitors for refilling. Itwill be necessary to specify the gas. Sparebottles containing these gases may be ordered.

ThePortable Calibration Chamber is a 3 li-ter (3000 cc) sample chamber with a springdriven mixing fan. A porthole allows thechamber to be placed on the sensor for calibra-tion. A syringe is included for accurate meas-urement of volatile test liquids. Sensorsshould be calibrated to a specific vapor forgreatest accuracy. A hydrocarbon sensor cali-brated for 50% LEL Acetone, for example,will detect all hydrocarbons and most combus-tible solvent vapors. It will accurately readONLY the % LEL of Acetone. The indicatedmeasures of volatile liquids in the next columnproduces 50% LEL vapor mixtures at 75°Fahrenheit (25° Celsius) temperature andstandard pressure when used with the PortableCalibration Chamber. See Appendix, section5.4.


Operation

Volatile liquids are not supplied by General Monitors.Below is a list of volatile liquids and the volume required

(in microliters) to produce 50% LEL in the 3 liter chamber.

Acetaldehyde 137Acetic Acid 140Acetone 113Acetonitrile 96Acrylonitrile 121Amyl Acetate 100Amylamine 156Benzene 71Butyl Acetate 137Butyl Acylate 132Butyl Alcohol 79sec-Butyl Alcohol 95tert-Butyl Alcohol 139Butyl Cellosolve 88Butyraldhyde 103Cyclohexane 86Decane 96Diethyl Ketone 104Diisobutyl Ketone 82Dimethylformamide 104p-Dioxane 105Dodecane 84Ether, Ethyl 120Ethanol (Ethyl Alcohol) 119Ethyl Acetate 120Ethyl Amine 140Ethyl Benzene 75Ethylene Oxide 91Gasoline 100 Octane 107Heptane, Normal 94Hexane, Normal 87Isopentane 100Isoprene 92Isopropyl Alcohol 94Isopropyl Ether 121JP-4 Jet Fuel 183Laktane 76Methanol 149Methyl Ethyl Ketone (MEK) 77Methyl Metacrylate 112Naptha (Petroleum Ether) 94Octane 100Pentane, Normal 106Propanol 1152-Propanol 93Propyl Acetate 108Propylamine 101Propylbenzene 68Propylene Oxide 99Styrene 63Tetradecane 80Tetrahydrofuran 100Tetrahydrofurfuryl Alcohol 89Toluene 711,1,1-Trichlorethane 459Trichloroethylene 440Triethylamine 103Vinyl Acetate 147Vinyl Ethyl Ether 100o-Xylene 67p-Xylene 82Xylenes 83

4.2 Digital Display Codes

The following codes will appear on the dis-play when the unit is placed in a mode otherthan the normal operating mode.

SU Start-Up- - (steady) Magnetic Switch Activated- - (flashing) Test Gas ModeAC Automatic CalibrationCP Calibration in ProgressCC Calibration is CompleteF1 Failed to Zero during calibrationF2 Failed to complete the calibrationF3 Failed to Span during calibrationF4 Sensor Reference Bead ErrorF5 Sensor Active Bead ErrorF6 Low Supply VoltageF7 EEPROM Verification FailureF8 Negative Zero DriftF9 Calibration check period exceeded

When the unit is in the normal operatingmode, the display will indicate the presence ofcombustible gas in percent of the Lower Ex-plosive Level (% LEL). The range of detec-tion is from 0 to 99% LEL.

99 (flashing) Over-Range, a gas concentrationexceeding 100% LEL is present.

SU This is displayed for about fifty secondsduring start-up and after a Fault conditionhas been corrected.

- - Appears on the display when the magnethas been properly positioned over theGMI Logo and when the Test GasMode can be or has been entered.


OperationDigital Display Codes(continued)

AC These codes appear on the displayCP during the calibration process. ForCC more information about these codes,

refer to Section 4.1 Calibration.

F1,F2,F3, These codes will appear on theF4,F5,F6, display if a Fault condition occurs.F7,F8,F9 For more information about these

codes, refer to Section 4.3 FaultCodes & Their Remedies.

4.3 Fault Codes & Their Remedies

The Model S104 has self-diagnostics incorpo-rated into the microprocessor’s program. If aFault is detected, the output signal will drop to0mA and a Fault code will be displayed. Theoutput signal will inform a remote displaymodule that the Model S104 is in the FaultMode. The display will indicate a Fault codethat can be viewed at the sensor site. Thereare nine Fault conditions that are monitored bythe microprocessor.

When a Calibration Fault (F1, F2, F3) has oc-curred and has been corrected, the unit willautomatically revert to the calibration processand the unit must be re-calibrated. If a Faultother than a Calibration Fault occurs, after it iscorrected, the unit will return to the Start-UpMode (SU).

F1 = Failed to Zero during Calibration

Faulty Sensor - If both Catalytic Beads arenot closely matched. This may happen as asensor approaches the end of its useful life orif the Beads have become corroded.AC-TION - Replace the sensor.

Gas Present- If the magnet was applied witha high level of gas present, the Model S104will not be able to obtain a valid ZERO.AC-TION - Ensure the sensor is in clean air.

F2 = Failed to complete the Calibration

This Fault will occur if the unit is placed in thecalibration mode and no gas has been appliedwithin six minutes.

F3 = Failed to Span during Calibration

Low Gas - If the gas concentration applied tothe unit does not give sufficient response for avalid SPAN parameter.ACTION - Use thecorrect gas concentration, i.e. 50% LEL.

Bad Sensor- If the sensor response has gonebelow an acceptable level.ACTION - Re-place the sensor.

NOTE: If the unit fails to calibrate and anF1or an F3 code is displayed, the calibrationgas must be removed from the sensor andthe sensor must see clean air for at least fiveminutes before a second calibration is initi-ated.


OperationFault Codes & Their Remedies(continued)

F4 = Sensor Reference Bead Error

This fault may occur as a result of one of thefollowing:l excessive negative driftl an open sensor reference beadl the sensor BLACK wire is disconnected

ACTION - Attempt to recalibrate the unit. Ifthis is unsuccessful make sure that theBLACK sensor wire is connected to the termi-nal block. If both of these actions do not curethe fault condition, then replace sensor.

F5 = Sensor Active Bead Error

This fault occurs if the sensor active bead be-comes open circuited or, if the sensor WHITEor the sensor RED lead becomes disconnected.ACTION - Check the WHITE and RED wiresor replace the sensor as appropriate.

F6 = Low Supply Voltage

This fault occurs if the supply voltage dropsbelow +17VDC approximately.ACTION -Ensure that the supply voltage is at least+20VDC at the Model S104.

Correcting this Fault will initiate the Start-UpMode.

NOTE: With long supply leads, a consider-able voltage drop may occur due to the elec-trical resistance of the leads.

The maximum cable resistance which theModel S104 can tolerate is dependent on thesupply voltage. A maximum of 20 ohms perconductor (40 ohms loop) at +24VDC mini-mum, or a maximum of 10 ohms per conduc-tor (20 ohms loop) at +20VDC minimum.

F7 = EEPROM Verification Failure

This fault occurs during calibration when anattempt to verify the calibration parametersjust written to the non-volatile memory fails.The usual cause of this is electrical interfer-ence corrupting the data (although on rare oc-casions it may indicate a problem within theelectronics module). ACTION - Place themagnet over the GMI Logo and the unit willattempt another EEPROM write and verify.

F8 = Negative Zero Drift

If the zero baseline of the sensor drifts 10% offull scale below zero for more than 20 secondsthis fault will occur. ACTION - A routine re-calibration will be required.

F9 = Calibration Check Period Exceeded

If the Model S104 is left in the Test Gas Modefor more than six minutes without a Test Gasbeing applied, this fault will occur.ACTION- Place the magnet over the General MonitorsLogo to return the unit to normal operation.

NOTE: Anytime a sensor is replaced, the unitshould be disconnected from all alarms, as theunit may go upscale upon power-up.

NOTE: Model S104 without display haslimited fault diagnostic capabilities. It cansense calibration, sensor and low voltagefaults. See figure 17 for LED sequences.


5.0 Appendix

5.1 Specifications

5.1.1 System Specifications

Sensor Type:Diffusion, low temp. catalytic bead

Standard industrial types: CombustibleGas; Solvent Special; Standard and HighTemperatureVersions (See section 5.4)

Typical Life: 3 years in normal service

Warranty:Two Years

Readout/Relay Modules (See section 5.4):DC100 Single Channel DisplayDC110 Eight Channel DisplayDC120 X/P Dual Channel DisplayDC130 Dual Channel DisplayTA102A Single Channel, 02 Series

Fault Conditions Monitored:Low DC Supply, Sensor Bead Open,Calib. Out of Range, EEPROM Failure

Accuracy:+3% LEL at ambient

Zero Drift:Less than 5% per year

Response Time:With 100% LEL Methane Applied,T50 < 10 sec. & T90 < 30 sec.

Approvals:FM approved

CSA certified to C22.2 No.152

Cenelec certified (display only withSST flame arrestor sensors)

CE Mark approval against EMC Directiveand Product Safety

5.1.2 Electrical Specifications

Input Power:24 VDC @ 250mA nom., 1A during SU20 to 30 VDC range

Output Current: (0-22mA @ 300 Ohms max. load)Fault: 0.0mACalibration: 1.5 mA (0.0mA optional)0-100%LEL: 4 to 20mAOver-range: 20 to 22mA

Electrical Classification:Class I, Division 1, Groups B, C & DNEMA 4x rated

Recommend Three Wire Shielded Cable:

Maximum distance between the ModelS104 and the power source.

AWG Feet Meters22 750 22820 1100 33518 1600 48816 2250 68514 4500 1372

For interfacing with 250 ohm inputimpedance devices, the followingmaximum cable lengths apply, withrespect to the Analog Signal, with thetotal loop resistance less than 300 ohms.

AWG Feet Meters22 1600 48820 2400 73018 3800 116016 5200 158514 9000 2740

NOTE: Good design practices dictate cablelengths conservatively shorter than the maxi-mum given values.


Appendix5.1.3 Mechanical Specifications

Weight (approx) 5.5 LB 2.5 kg

Length 6.34" 161 mm

Height (w/bolts) 3.40" 86 mm

Width at the base 4.10" 104 mm

Between mounting hole centers5.00" 127 mm

Between outside edges of mounting flanges6.00" 152 mm

5.1.4 Environmental Specifications

Operating Temperature Range:

Sensor (See section 5.4)-65°F to 200°F-55°C to 93°C

High Temperature Sensor(See section 5.4)

-65°F to 400°F-55°C to 200°C

Electronics (pc board assemblies)-40°F to 140°F-40°C to 60°C

Storage Temperature Range:

Smart Sensor Assembly-58°F to 158°F-50°C to 70°C

Humidity Range:

10 to 95% Relative Humiditynon-condensing


Appendix

5.2 Engineering Documentation

5.2.1 Termination & Outline Drawings

19

NOTE: The Calibration Switch isonly available on the Model S104without a display. If the calibra-tion switch is not present, it willbe replaced with a housing entryplug. If the Model S104 is or-dered with a display, the TB1 des-ignations for positions 2, 3, 4 & 5will not be used.


figure 19

Appendix

20

NOTE: The CalibrationSwitch is only available onthe Model S104 without adisplay. If the calibrationswitch is not present, it willbe replaced with a housingentry plug.

figure 20


Appendix5.2.2 Termination & Outline Drawings CE Marked Unit

21

figure 21


Appendix

5.3 Ordering Information

5.3.1 Configuration Codes

The standard configuration for the ModelS104 is: S104 - 3 0 0 - 1 01 - 1 0 1

S104 - 3 0 0 -o oo -o 0 o

22

Active Channels0 = No Sensor, Electronics Only1 = Sensor Included ........ (standard)

Combustible Gas Sensor (See section 5.4):00 = No Sensor01 = 10001-1 ...................(standard)02 = 10001-1R03 = 10014-104 = 10014-1R05 = 10022-106 = 10058-107 = 10058-1R08 = 10059-109 = 10164-110 = 10387-411 = 10391-112 = Consult the Factory

Display Option:1 = No Display CSA, FM(standard)2 = With Display CSA, FM3 = With Display CSA, Cenelec

Calibration Signal:1 = 1.5 mA.......................(standard)2 = 0.0 mA


Appendix5.3.2 Spare Parts & Accessories

To order spare parts and/or accessories, pleasecontact your nearest General Monitors Repre-sentative or General Monitors directly andgive the following information:

l Part Number of Spare Part or Accessory

l Description of Spare Part or Accessory

l Quantity of Spare Part or Accessory

Sensors:

10001-1 General Purpose, Alum.,

10001-1R General Purpose, Alum.,Poison Resistant

10014-1 General Purpose, Alum.,High Temperature

10014-1R General Purpose, Alum.,Hi-Temp, Poison Resistant

10022-1 General Purpose, Alum.,Industrial PTB

10058-1 General Purpose, SST

10058-1R General Purpose, SST,Poison Resistant

10059-1 General Purpose, SST,Industrial PTB

10164-1 Hydrogen Specific, Alum.

10387-4 General Purpose, Alum.,Super Poison Resistant

10391-1 General Purpose, SST,Hi-Temperature

10102-1 Dummy Sensor

Sensor Housing:

10252 Universal Housing

Sensor Accessories:

10460-2 Test Gas Applicator

10041 Duct Mounting Plate

10044-1 Dust Guard Kit - 1 Guard12 Replaceable Screens

10042-1 Replaceable Screens,Box of 12

10395-1 Splash Guard Assembly

50060-1 H2S Guard Filter

50061-1 Purafil Insert Assembly

10110-1 Dust Guard Assembly

1800822 Dust Guard, Sintered SST

Calibration Equipment:

10221-1 Model RC-3, RemoteCalibrator Assembly

10378-1 RC-3 InterconnectionAssembly

10345-1 RC-3 Position Indicator

10375-1 RC-3 Battery Assembly

10233-1 RC-3 Wind Shield

1400200 3 Liter CAL Chamberwith syringe

1400204 Fan Motor for the 3 literChamber

1400207 Fan Blade for the 3 literChamber


AppendixCalibration Equipment (continued)

928-700 Dish for the 3 liter Chamber

928-715 250 microliter syringe

1400150-M Portable Purge Calibrator,Methane @ 50% LEL

1400150-H Portable Purge Calibrator,Hydrogen @ 50% LEL

1400150-BD Portable Purge Calibrator,Butadiene @ 50% LEL

1400150-B Portable Purge Calibrator,Butane @ 50% LEL

1400150-E Portable Purge Calibrator,Ethane @ 50% LEL

1400150-PR Portable Purge Calibrator,Propane @ 50% LEL

1400155-M Replacement Cylinder,Methane @ 50% LEL

1400155-H Replacement Cylinder,Hydrogen @ 50% LEL

1400155-BD Replacement Cylinder,Butadiene @ 50% LEL

1400155-B Replacement Cylinder,Butane @ 50% LEL

1400155-E Replacement Cylinder,Ethane @ 50% LEL

1400155-PR Replacement Cylinder,Propane @ 50% LEL

922-009 Pressure Regulator Gauge

1400152-1 Small Calibration Cup

1400154 Large Calibration Cup

Smart Sensor (S104) Replacement Parts:

30441-1 Control Board Electronics

30261-1 Converter Board Electronics

30080-1 Display Board Electronics

30343-2 Cover Assy (with window)

30343-3 Cover Assy (no window)

925-5007 O-Ring for Cover Assy

30060-1 Calibration Magnet

30021-1 Calibration/LED Switch

Recommended Spare Parts for One (1) Year:

1 Extra Calibration Magnet (30060-1)

1 Extra Screwdriver (10450-1)


Appendix

5.4 FMRC Approval

Factory Mutual Research Corporation1151 Boston-Providence TurnpikeNorwood, Massachusetts 02062

Approval of the transmitter does not includeor imply approval of apparatus to which thetransmitter may be connected and which proc-esses the electronic signal for the eventual enduse. In order to maintain an FMRC approvedsystem, the control instrument, to which thesubject instrument is connected, must beFMRC approved.

The following sensors have been FMRCapproved for use with the Model S104:

l 10001-1 Aluminum Body GeneralPurpose Combustible Gas Sensor

l 10058-1 Stainless Steel Body GeneralPurpose Combustible Gas Sensor

The following apparatus have been FMRCapproved (although they have not beenverified as part of a Model S104 system):

l Model DC100 Single Channel ReadoutRelay Display Module

l Model DC110 Eight Channel ReadoutRelay Display Module

l Model DC120 Explosion Proof DualChannel Readout Relay Display Module

l Model DC130 Dual Channel ReadoutRelay Display Module

Factory Mutual Research Corporation hastested the Model S104 according to the crite-ria listed under FMRC Approval Standardsfor Combustible Gas Detectors, Class Num-bers 6310 & 6320.

FMRC has tested the Model S104 using thespecifications listed in section 5.1, permittingan operating temperature range of -40°F to+140°F (-40°C to +60°C), a general purposesensor (10001-1 or 10058-1) attached to thehousing (i.e. not remoted), calibration per-formed with a General Monitors’ PortablePurge Calibrator using 50% LEL gas (Meth-ane, Hydrogen, Butadiene, Butane, Ethane orPropane) and the procedure listed in section4.1 of this Instruction Manual.


GENERAL MONITORS Model S104

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