Xentra 4100 Service

8/17/2019 Xentra 4100 Service

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Xentra Analyser Service Manual

Ref: 04000/002C/2Order as part 04000 002C


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I

HAZARD WARNINGS

1. LETHAL VOLTAGES: THE ELECTRICAL POWER USED IN THISEQUIPMENT IS AT A VOLTAGE HIGH ENOUGH TO ENDANGER LIFE.

2. BEFORE CARRYING OUT SERVICING OR REPAIR THE EQUIPMENTMUST BE DISCONNECTED FROM THE ELECTRICAL SUPPLY.

TESTS MUST BE MADE TO ENSURE THAT DISCONNECTION ISCOMPLETE.

3. IF FOR ANY REASON THE POWER SUPPLY CANNOT BEDISCONNECTED, FUNCTIONAL TESTING, MAINTENANCE ANDREPAIR OF THE ELECTRICAL UNITS IS ONLY TO BE UNDERTAKEN

AS A LAST RESORT AND MUST BE CARRIED OUT BY PERSONSFULLY AWARE OF THE DANGER INVOLVED.

WARNINGS, CAUTIONS AND NOTES

This publication includes WARNINGS, CAUTIONS AND NOTES whichprovide,

where appropriate, information relating to the following:

WARNINGS : Hazards which will result in personal injury or

death.

CAUTIONS : Hazards which will result in equipment or property

damage.

NOTES : Alert the user to pertinent facts and conditions.

NOTICE: This service manual for Xentra Analyser covers disassembly proceduresfor this equipment, and brief technical descriptions of component parts of theequipment. It should be thoroughly read and retained by the service engineer.


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II

NOTES


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III

CONTENTS

Section

1. IntroductionRead this section before commencing any work on the analyser.

2. Product OverviewProvides a mechanical and electronic overview. These should be read toprovide orientation for the subsequent sections.

3. Gas Sensor Module Technology OverviewProvides an overview of the technology used in the Xentra Analysers.

4. Spares ListLists the available spares. No other spares are available.

5. Fault FindingDescribes fault finding procedures.

6. Parts Replacement ProceduresDescribed procedures to replace and test parts.

7. Software MaintenanceDescribes software maintenance procedures.

8. Engineering Drawings

Contains a list of drawings and schematics attached to this manual.


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IV

NOTES


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1.1

SECTION 1: INTRODUCTION

LIST OF CONTENTS

Section Page

1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3

1.2 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3

1.3 Location of components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

1.4 Transducer site numbering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

1.5 Output numbering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

1.6 The Xentra user interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6

1.7 Displaying additional information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8

1.8 Permitted Analyser/Transducer configurations . . . . . . . . . . . . . . . . . . 1.8

LIST OF FIGURES

Figure Page

1.1 Key features of the Xentra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5

1.2 Xentra measurement display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7

LIST OF TABLES

Table Page

1.1 Transducer FSD values and availablility in Product Range . . . . . . . . . 1.9


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1.2

NOTES


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1.3

1 INTRODUCTION

1.1 Introduction

This manual contains essential information regarding servicing of Servomex Xentra

Analysers.

A QuickStart manual is included in the front of this manual, reference part number 04000/003C. This details software configuration and operation of the analyser.

A separate Installation manual is also available, reference part number 04000/005C.

Extra copies of any manual may be ordered from Servomex.

This service manual is intended for use by Servomex trained service personnel. Themanual contains technical descriptions, fault diagnosis information, part removal,

refitting and test instructions as well as electrical and mechanical drawings andillustrations.

Repairs to PCB's are effected by board replacement. Component replacement is notrecommended. The only exception to this is the display lamp invertor mounted on thekeypad.

WARNING

The user should note that the Xentra instrument contains no user serviceable

parts inside. The instrument enclosure protects the user from electric shockand other hazards. All servicing should be referred to qualified service

personnel.

1.2 General description

The Servomex Xentra chassis is an analyser into which up to four gas sensor modulesmay be fitted. The chassis provides power, gas connections and other support

functions to the sensors and calculates associated sample gas concentrations. Theseconcentrations are then displayed on the analyser display screen and may be directedto the analogue outputs and/or the serial RS232 output.

The Xentra chassis also supports two external analogue input signals. The data fromthe external inputs may be displayed on the screen, output to the analogue outputsand/or the serial RS232 output.

Designed for use in modern industrial and laboratory environments, the analyser iscontrolled using an integral microprocessor which provides significant user flexibility.


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1.4

The Xentra 4100 is designed to meet the control and product quality monitoringrequirements of industrial gas producers and users. It can monitor up to four gasstreams simultaneously with independent autocalibration for each stream (providedsufficient extra relays are installed).

The Xentra 4200 is intended for monitoring flammable samples, but not thosecontaining hydrogen or acetylene for which the Xentra 4210 must be used. Again, upto four gas streams may be monitored simultaneously and independent autocalibrationcan be used with each stream. The zirconia transducer is not available for theseanalysers.

The Xentra 4900 is a continuous emissions monitoring (CEMs) analyer with a maximumof four transducers with either one or two sample streams. Independent autocalibrationis available for each stream or transducer.

None of the above are suitable for use with corrosive samples.

A number of optional features are available for the Xentra. These may include thefollowing, depending upon analyser configuration:-

Flow meters and needle valves (on the 4900C only) to monitor andcontrol sample gas flow through the instrument.

A sample filter to protect the gas sensor modules from particulatecontamination.

A sample flow alarm to monitor the sample flow and alarm when the flowfalls below a defined level. This is only available on the 4900C.

An Autocalibration manifold (for a single sample stream) to allow theinstrument to be calibrated without user intervention. On the 4100C thisis only suitable for paramagnetic transducers.

Additional relay output contacts to allow autocalibration of the analyser via externally located valves.

Additional signal output cards to extend the number of analogue outputs

and relay outputs available to the user.

Note

The following abbreviations are used throughout this manual:

Gfx Gas filter correlation infra-red transducer IR Pulsed infra-red transducer Pm Paramagnetic transducer Zr Zirconia transducer


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1.5

Figure 1.1 Key features of Xentra

1.3 Location of components

Figure 1.1 identifies the location of the key features of the Xentra analyser, note that theidentification label (including serial number information) is located on the underside of the unit towards the rear.

Key: A FRONT VIEW B REAR VIEW 1 Sample filter (optional) 2 Flowmeter(s) (optional) 3 Display 4 Keypad 5 Display adjustment 6 Needle valve(s) (optional) 7 Rack mounting brackets

(optional)

8 Sample inlet(s) 9 Mains power connector 10 Fan and filter 11 Sample outlet(s)12 Functional earth13 Serial output port14 Signal terminals15 Screen


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1.6

1.4 Transducer site numbering system

The four internal transducers are assigned site locations represented as I1, I2, I3 andI4 on the display.

In the case of the Xentra 4100 and the Xentra 4200, each transducer is served by adiscrete sample inlet and outlet connection on the rear panel.

In the case of the Xentra 4900, either one or two sample streams may be specified -consequently only inlets/outlets numbered 1 and 2 will be used.

1.5 Output numbering system

Identification numbers appear on the rear label to identify the terminals where eachoutput appears and on the display when the outputs are being configured. These have

a two digit identification number of the following format: Card number . Output No.

eg. the outputs fitted as standard on the SIB pcb in card position 1 are :

1.1 Analogue output1.2 Analogue output1.3 Relay

1.4 Relay1.5 Relay

1.6 The Xentra user interface

The Xentra user interface consists of a keypad with nine keys and a large edge-

lit LCD display ( see Figure 1.1).

Use of the keypad and display is detailed in the QuickStart Manual, which

includes relevant illustrations and a copy of the software menu map.

Note

Reminder: some user interface operations require the use of a password.There are two passwords:

1) a supervisor password which gives access to SETUP and CALIBRATION

2) an operator password which gives access to CALIBRATION only.

Both are factory set to 4000, but these may be changed by the user.


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1.7

Figure 1.2 Xentra measurement display

The following details act as a reminder to the information normally shown on themeasurement display, referenced in figure 1.2.

Key: No. module location (2 characters)Value measurement value (6 characters)Unit engineering units (3 characters)Name A user defined message (6 characters).

The module location defines which transducer the process variable represents.

The letter 'I' indicates an internal gas sensor module, the letter 'E' indicates anexternal gas transducer (user supplied) and the letter ‘D’ indicates a derivedmeasurement (as in the case of NOx derivations from an NO transducer installedin a Xentra 4900C). The letter is followed by a number defining the gas sensor module site number - see section 1.4.

The measurement value indicates the concentration measured.

The engineering units field is a user defined 3 character message identifying theunits of measurement. The engineering units field is a message only. Changingthe engineering units message has no effect on the displayed value.

The user defined message field is a 6 character field to represent the processvariable name or tag number.


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1.8

1.7 Displaying additional information

Aside from the measurement display, the Xentra may be interrogated to displaythe following useful information (refer to QuickStart Manual):

alarms present display any current sample concentrationalarms

maintenance faults present display any current maintenance faults

failure faults present display any current failure faults

alarm history An entry is made in the history buffer eachtime an alarm appears or is cleared. Note:that if hysteresis has been specified whenconfiguring an alarm, then the alarm will notclear until the concentration has reached thealarm level plus the hysteresis.

maintenance fault history An entry is made in the history buffer eachtime a fault appears or is cleared.

failure fault history An entry is made in the history buffer eachtime a fault appears or is cleared.

calibration history An entry is made in the history buffer eachtime a calibration or calibration check isperformed.

diagnostics information The signals from gas sensors may bedisplayed. These may be useful in diagnosingany problems which may arise.

1.8 Permitted Analyser/Transducer configurations

Warning

The following table shows the availability of transducers in the current XentraProduct range.

It is not permitted to deviate from the list for 4200C and 4210C by installingalternative transducer configurations.


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1.9

Table 1.1 Transducer FSD values and availablility in Product Range:

Transducer FSD 4100 4200

4210

4900

Gfx1210 CO Standard sensitivity 3000vpm CO - -

Gfx1210 CO High sensitivity 500vpm CO

Gfx 1210 SO2 Standard sensitivity 2500 vpm SO2 - -

Gfx 1210 NO High sensitivity 1000 vpm NO - -

Gfx1210 CO2 High sensitivity 100vpm CO2 -

Gfx 1210 CH4 High sensitivity 500 vpm CH4

Gfx 1210 N2O High sensitivity 500 vpm N2O

IR 1520 100% CO2 100% CO2

IR 1520 50% CO2 50% CO2

IR 1520 25% CO2 25% CO2

IR 1520 10% CO2 10% CO2

IR 1520 5% CO2 5% CO2

IR 1520 2.5% CO2 2.5% CO2

IR 1520 1% CO2 1% CO2

IR 1520 0.5% CO2 0.5% CO2

IR 1520 0.25% CO2 0.25% CO2 IR 1521 100% CH4 100%CH4 - -

IR 1521 50% CH4 50% CH4 - -

IR 1521 25% CH4 25% CH4 - -

IR 1521 5% CH4 5% CH4 - -

IR 1522 50% CO 50% CO - -

IR 1522 25% CO 25% CO - -

IR 1522 10% CO 10% CO

IR 1522 2.5% CO 2.5% CO

IR 1522 1% CO 1% CO

Pm 1158 O2 Control 100% O2

Pm 1111 O2 Basic 100% O2 -

Pm Purity O2 (4100995) 100% O2 - -

Zirconia 703 O2 Trace 210000vpm O2 - -

Zirconia 704 O2 Trace 210000vpm O2 -


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1.10

NOTES


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2.1

SECTION 2: PRODUCT OVERVIEW

LIST OF CONTENTS

Section Page

2.1 Mechanical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3

2.2 Sample Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7

2.3 Electrical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13

LIST OF FIGURES

Figure Page

2.1 4100C Flow driven schematic, Zirconia sensor . . . . . . . . . . . . . . . . . . 2.7

2.2 4100C Pressure driven schematic, Zirconia sensor . . . . . . . . . . . . . . . 2.8

2.3 Sample gland plate without autocalibration . . . . . . . . . . . . . . . . . . . . . 2.9

2.4 Sample gland plate with autocalibration . . . . . . . . . . . . . . . . . . . . . . . 2.10

2.5 Sample gland plate with external autocalibration . . . . . . . . . . . . . . . . 2.11

2.6 Electronic system block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13

LIST OF TABLES

Table Page

2.1 Sample port vs transducer type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.12

2.2 Microprocessor LED states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16


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2.2

NOTES


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2.3

2 PRODUCT OVERVIEW

2.1 Mechanical Overview

2.1.1 General

Refer to figure 6.1

The Xentra consists of a sheet metal chassis [4] and cover [3] fixed with either 9 or 11 screws [2]. The chassis contains the gas sensor modules, associatedelectronics and sample system. On the front of the chassis is a plastic mouldedfascia [5] which is used to mount the display and keypad. Mounted on the frontof the chassis but projecting through the fascia are a sample filter and twoFlowmeters which are optional. The fascia is fixed to the chassis using 8 screws(Figure 6.2[13]).

2.1.2 Keypad

Refer to figure 6.2

The keypad consists of a PCB [21] and a silicone rubber overlay [22]. The rubber overlay has nine keys moulded into it, each has a rubber contact pill whichmakes contact with the PCB when the key is pressed. The fascia has fivelocating pegs [28] which are used to locate the rubber overlay and keypad PCB.The keypad is then fixed to the fascia using four screws [20] with the rubber

overlay sandwiched between. One of the keypad PCB fixing screws has aspacer [27] which prevents the screw breaking through the front of the fascia.

The invertor [41] which provides a high voltage for the cold cathode fluorescentlamp is mounted on the keypad PCB. The potentiometer for adjustment of thedisplay viewing angle is mounted on the keypad PCB [21].

2.1.3 Fascia EMC components

Refer to figure 6.2

The display window [43] is fixed into the fascia independently of the display. Theinner surface of the window is metallised, this metallisation is connected to aconductive coating on the inner surface of the fascia by copper tape withconductive adhesive [30]. A web wall on the inner surface of the fascia whichgoes around the display and keypad carries an EMC gasket [31], this is used toconnect to the front of the chassis thus providing a complete conductiveenvelope around the keypad and display.


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2.4

2.1.4 Display

Refer to figure 6.2

The display is fixed to the fascia by four screws [23], it has no user serviceable

parts.

2.1.5 Card frame

Refer to figure 6.9

The card frame, mounted at the rear of the chassis, consists of a front card-frame [10] and a rear card-frame [7]. Both card-frames have snap-in plastic cardguides [11]. The front card frame fixes to two studs in the base of the chassis.The rear card-frame is suspended from the top rear of the chassis using two

screws [3] which fix into threaded inserts in the chassis. The Motherboard [9] issuspended between the two card-frames. The Motherboard has threaded insertswhich are used to fix it to the card-frames using four screws [5]. Three fixings areprovided at the rear of the Motherboard and one at the front. The front of theMotherboard protrudes through the front card-frame to give support in the regionof the connector

Between one and four Terminal boards [6] may be fitted. These plug into theMotherboard, but the connector which is presented to the customer at the rear of the chassis is sandwiched between the rear of the chassis and the rear card-frame. Thus the Terminal boards form an integral part of the card-frame. Thefollowing boards plug into the Motherboard and are supported by card-guides:

Refer to figure 6.4

Power supply [19]Microprocessor [6]Sensor interface [2]Three option boards [3,4,5]Multiplexer board [1]

The Power supply has a metal case and is given additional support by a screw(Figure 6.4 [18]) which fixes it to the card frame. All boards which plug into theMotherboard have handles to aid extraction except the Microprocessor boardand power supply.


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2.6

2.1.10 Gas sensor modules

Zirconia example shown in figure 6.10.

The gas sensor modules mount to the base of the chassis using studs fixed into

the chassis base [16]. The studs are fitted with nuts with integral lockingwashers. The gas sensor modules are provided with slots so that the nuts do notneed to be removed from the mounting studs. Once the nuts are loosened thegas sensor module may slide sideways then upwards for removal.

2.1.11 Maintenance of EMC performance

Refer to figure 6.3

To ensure that EMC performance is maintained all cover screws should be

refitted and tightened. The conductive gaskets[1] along the front edge of thechassis [6] and those on the fascia should also be fitted and replaced wherenecessary.

2.2 Sample System Options

Throughout this section, the terms ‘flow driven’ and ‘pressure’ driven are used:

The flow driven option is supplied for applications where the sample flow is tobe controlled by the customer, prior to entry into the analyser. Minimum and

maximum flows are analyser or transducer module dependent. For more detailon specific flowrates please refer to the Installation manual.

The pressure driven option (only available on 4100C and 4200C) has beenspecifically designed to maintain optimum sample flowrate for an inlet pressureof 5psig +/- 3psig (35kPag +/- 21kPag). The sample system operates byrestricting the sample flow and redirecting excess sample down a bypass route

to the outlet. The system will accommodate minor changes in inlet pressure buta stable inlet pressure is recommended.

2.2.1 Xentra 4100C Options

Each transducer module is served by it’s own individual sample system and the4100C is offered with a choice of two sampling systems: flow driven andpressure driven. These sampling systems are transducer module dependent anda multi measurement analyser could contain a mixture of both. The specificanalyser configuration can be accessed via the user interface, where the featureand options for the build are stored.


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2.7

Figure 2.1 4100C Flow driven schematic, Zirconia sensor

Figure 2.2 4100C Pressure driven schematic, Zirconia sensor

Flow Driven Option

Refer to Figure 2.1 for a typical (Zirconia) installation

Pressure Driven Option

Refer to Figure 2.2 for a typical (Zirconia) installation


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2.8


Each transducer module is served by it’s own individual sample system and the4200C is offered with a choice of two sampling systems: flow driven andpressure driven. These sampling systems are identical to those used in the

4100C above (note: Zirconia transducers are not permitted), being transducer module dependent and a multi measurement analyser could contain a mixtureof both. The specific analyser configuration can be accessed via the user interface, where the feature and options for the build are stored.


Each transducer module is served by it’s own individual sample system. The4210C is only available with flow driven sample systems, with a discrete metallicinlet and outlet tube for each transducer.


The 4900C offers the ability to install a maximum of four transducers with either one or two sample streams. These sample streams are flow dependent andmust be controlled between 500ml/min to 1500 ml/min.

2.2.5 Optional Flowmeter(s) and needle valve(s)

Refer to figure 6.2

The Flowmeter consists of a flow tube [9,10] supported between end-blocks[7,8,38,39]. The end-block spigots accommodate 'o' rings [11,12] which seal tothe flow tubes. Each flowmeter has a moulded plastic cover [4,5] which providesaccess to the flow tube [9,10] for cleaning. When the Flowmeters are not fittedthe cover is replaced by a blank. The cover or blank is fixed by a screw [3]accessible from inside the chassis [42].

Where fitted, needle valves [16,17] are mounted to the bottom end block [38,39].The needle valve control knob [40] has a moulded rubber cover [1].

2.2.6 Optional Sample Filter - Internal

(See 2.1.8 for external sample filter)

Refer to figure 6.2

The sample filter housing [26] has a clear polycarbonate cover [32] which maybe unscrewed with the aid of the spanner provided with the Xentra to gain

access to the filter element [33]. The filter cover [32] is sealed to the filter housing using an 'o' ring [34]. When the sample filter is not fitted a blank is fittedto the fascia [29]


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2.9

Figure 2.3 Sample gland plate without auto calibration

2.2.7 Sample connections

WARNING

The sample and calibration gases supplied to the instrument may be

toxic, flammable* or asphyxiant. Verify that connections are leak free atfull operating pressure before proceeding with admitting such samples.

Instrument vent gases may also be toxic, flammable* or asphyxiant andshould be treated accordingly. They should not be vented into anenclosed area.

Before performing any service operation ensure that the instrumentsample system has been flushed with inert gas before opening sample

connections. This is to prevent accidental exposure to toxic, flammable*

or asphyxiant gases.

*The Xentra is not suitable for operation with corrosive gas samples.The 4100C and 4900C are not suitable for operation with flammable gassamples.

Sample and calibration gases pass into and out of the chassis via a gland platemounted on the rear of the chassis. The version of the gland plate will dependon which auto calibration option has been supplied.


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2.10

Figure 2.4 Sample gland plate with internal auto calibration

Pressure or flow driven non autocalibration units

The sample gland plate without autocalibration is shown in figure 2.3. Thisprovides up to four sample inlets and a corresponding outlet for each inlet. Asingle sample inlet is provided for each gas stream.

Pressure or flow driven internal autocalibration units

When the internal autocalibration feature is supplied a valve manifold is mountedin the sample gland plate (see figure 2.4). This provides ports for sample inletand outlet plus additional inlets for two calibration gases. The autocalibrationmanifold is installed on gas stream 1. Again a single sample inlet is provided oneach gas stream. This option is not suitable for use with toxic samples.

Pressure or flow driven external autocalibration units

The gland plate supplied for the external autocalibration option (see figure 2.5).

There are no inlets for calibration gas. Instead an electrical connector carriesdrive signals which may be used to control solenoid valves mounted outside theinstrument case.


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2.11

Figure 2.5 Sample gland plate with external auto calibration


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2.12

Sample port sizes and thread types are given in table 2.1, note: not all sensor types

are available in all analyser models.

Table 2.1 Sample port vs transducer type

Analyser/Gas sensor module type

Sampleinlet

Sampleoutlet

Lowcal gas

Highcal gas

4100C Zirconia c" OD*stainlesssteel stub

¼" NPTfemale

N/A N/A

4100C

and

4200C

1520 Series IR c" NPTfemale

¼" NPTfemale

N/A N/A

Paramagnetic c

" NPTfemale ¼" NPTfemale N/A N/A

Infrared Gfx c" OD*stainlesssteel stub

¼" NPTfemale

N/A N/A

4210C All availablesensor types

c" OD*stainlesssteel stub

c" ODstainlesssteel stub

N/A N/A

4900C Standard c

" NPTfemale ¼" NPTfemale N/A N/A

4100Cor 4900C

OptionalInternal auto cal

c" NPTfemale

¼" NPTfemale

c" NPTfemale

c" NPTfemale

*Note: An external filter may be specified, in which case the inlet connections will be‘Swagelok’ 1/8" OD female compression.

2.2.8 External filter

An external filter (stainless steel) may be fitted to the inlet of either Zirconiasensors or Infrared benches. The filter should be fitted directly to the analyser inlet or, if preferred, at a convenient point in the sample inlet line.


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2.13

Figure 2.6 Electronic system block diagram

2.3 Electrical Overview

Figure 2.6 shows the system block diagram, the following sub-sections detailindividual elements within the system.

2.3.1 Power distribution

Refer to figure 6.4

Mains power

Electrical power enters the analyser via an IEC CE22 connector [9]. Thisconnector provides an ON/OFF switch, filtering and mains voltage selection aswell as fusing. Power is taken on to the Motherboard [20] via a 4 way connector

[11]. Mains power is distributed on the Motherboard to the transformer [17] viaa 4 way connector [12] and to the switched mode power supply [19] which plugsdirectly into the Motherboard.


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2.14

Transformer

The transformer has split primary windings allowing voltage selection between85 to 132V ac or 170 to 264V ac. The transformer provides power for the gassensor modules and an auto transformed tapping for auxiliary power, this

tapping is not used on the Xentra. The auxiliary power tapping is fused via F2which is mounted on the Motherboard but accessed from the rear of the chassis.Each primary winding has a self-resetting over-temperature cutout, whichoperates at 110°C.

There are two versions of the transformer, one provides power for two gassensor modules and the other provides power for four gas sensor modules. Thetransformers have one secondary winding per gas sensor module, nominally 18-0-18 V ac.

Gas sensor module power

The transformer secondary windings are connected to the Motherboard via aconnector [13]. The secondary windings are then routed on to the Multiplexer board [1] via connector [22]. Each secondary winding has two soldered-in fuseson the Multiplexer board. The secondary windings are then routed to the gassensor modules via four connectors on the Multiplexer board.

Switched mode power supply

The switched mode power supply [19] operates between 85 to 264V and is notaffected by mains voltage selection. It provides +15V, -15V, +5V and 24Visolated supplies. The isolated 24V positive supply is grounded on theMotherboard to generate -24V for the display viewing angle adjustment.

A short circuit or overload on the 24V rail will shut down all of the outputs. Thesewill run at approximately 0.5V as the power supply tries to restart. A short circuitor overload on the +5V, +15V or -15V rails will not affect the other rails.

Display lamp drive

The display lamp runs at approximately 300V ac 35 kHz, the voltage required tostrike the lamp initially is 600V. The lamp is driven from an invertor mounted onthe keypad PCB which uses the 24V supply.


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2.15

2.3.2 Signal processing

Standard gas sensor module connector

The Gas sensor modules and Multiplexer board are connected via a 20 way

ribbon cable. All Gas sensor modules have a common pin-out. This means thatGas sensor modules may be plugged into any of four positions on theMultiplexer board.

Signal multiplexing

Refer to figure 6.4

The Sensor interface board [2] has one digital input and one analogue input for interfacing with transducers. Analogue and digital signals are multiplexed into

these inputs using three 'probe select' (or transducer select) lines to select whichtransducer is accessed and four 'control lines' to select which signal within thetransducer is to be accessed. The multiplexers are on the Multiplexer board, the'probe select' and 'control' lines are generated from the Sensor interface board.

Signal scaling

The gas sensor modules used in the Xentra output 0 to 1 V signals, theMultiplexer board re-scales the signals. The signals are multiplied by 2 and a

0.5 V offset added, finally the signals are potted down to 80%. The A to D hasa full scale of 2.5V. The 0.5V offset provides under range and the 80% pot downprovides over range.

Removal of offset variation

The 0.5V offset may vary. In order to null out this variation the software accessesa 0V input signal and measures the actual 0.5V level. This offset null occursonce per minute.

Span voltage reference

To reduce the span temperature coefficient of the electronics a span referencevoltage is provided which is read once every ten seconds. If the resultantreading is outside of acceptable limits the A-D convertor is re-calibrated. If thereading is still outside of acceptable limits after three calibration attempts, a faultis indicated. The A-D has digital registers and may occasionally be corrupted byelectrical interference. However this should be self correcting unless theinterference is persistent.


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2.16

2.3.3 Microprocessor board

Refer to figure 7.1

The Microprocessor PCB [1] (also, figure 6.4 [6]) runs software specific to the

gas sensor module population and interfaces to the following via themicroprocessor bus: Display, Keypad, Sensor interface board and option boards.The software is contained in two EPROMS [4,5] which are known as 'Firmware'once programmed. The microprocessor board also contains RAM [6,7] for temporary data storage, EEPROM [8] for indefinite storage of calibration and set-up information such as analogue output ranging and a real time calendar/clockwhich continues to keep time during power down by drawing power from asuper-capacitor. The super capacitor will power the calendar/clock for between2 days and 2 weeks.

Note: If the analyser is powered up with either its sensor interface or any option

boards removed any set-up information for those boards will be lost.

The green LED at the top of the microprocessor board indicates that themicroprocessor is not being reset when illuminated continuously. Themicroprocessor board contains a watchdog timer which must be re-initialised bythe software every half second. If the software fails to re-initialise the watchdogthe microprocessor will be reset thus extinguishing the green LED momentarily.If the software can not run eg because the RAM has failed the microprocessor will be continually reset, under these circumstances the green LED appears toflash.

The two red LED's at the top of the microprocessor board are extinguished bythe software when memory checks have been completed following a reset.Following successful memory checks the message 'SYSTEM OK' will appear onthe display. Table 2.2 shows the sequence of LED states.

TABLE 2.2 Microprocessor LED state

State D3 RED

D2 RED

D1 GREEN

Initial state,microprocessor isreset

ON ON OFF

Reset line released ON ON ON

RAM test OK ON OFF ON

EPROM test OK OFF OFF ON


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2.17

2.3.4 Solenoid valve drives

The four control lines are latched into a 'D' type latch on the Multiplexer board,two of these latched lines are used to drive the solenoid valves via transistors.

2.3.5 Sensor interface board

The sensor interface board consists of the following: digital outputs for multiplexing of signals, an A to D convertor to receive multiplexed analoguesignals , a digital input for multiplexed digital signals, two isolated analogueoutputs and three volt free relay contacts. The board provides an identificationcode which the microprocessor can read to identify that the board is fitted is of the correct type.

2.3.6 Option boards

Option boards are depopulated versions of the Sensor interface board. Whichhave three relays plus dual isolated current outputs.

2.3.7 Multiplexer board

The multiplexer board buffers signal from the gas sensor modules, providesoffset and scaling and routes them to the Sensor interface board via the

Motherboard. Routing of the signals is performed using multiplexers under control of the microprocessor. Electrical power is provided to the gas sensor modules from the Multiplexer board.

The multiplexer board also provides signal routing and multiplexing for the twoexternal analogue inputs.

The pressure transducer site (SK2) on the multiplexer board is only used in the4900 to provide a flow alarm function based on a differential pressuremeasurement.

A 2.5V voltage reference is provided for span compensation of the electronics,this signal is read via the A-D convertor and the compensation performed bysoftware.

The control lines from the Sensor interface board are fed into a 'D' type latch andlatched in under control of the microprocessor to drive the solenoid valves via adrive transistor.


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2.18

2.3.8 Mother board

The Mother board has no active components. It is used to connect the followingitems: Switched mode power supply, microprocessor board, Sensor interfaceboard, option boards, Terminal boards, Multiplexer board, transformer, fans and

solenoid valves.

The Mother board carries a fuse for the transformer auxiliary winding which isaccessible from the rear of the chassis. A terminal block which is accessible fromthe rear of the chassis is provided for connection of: external current inputs withvalidation signals, range change input, autocal initiate input.

2.3.9 Terminal board

Between one and four Terminal boards may be fitted. The isolated current

outputs and relays from the Sensor interface board and option boards areconnected to the Terminal board via the Mother board. The Terminal boardpresents these signals on a two-part connector at the rear of the chassis.Filtering is fitted to each of these connections for EMC. Each Terminal board isfitted with two small pieces of conductive gasket to provide an RF connection tothe chassis, this is again for EMC.


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3.1

SECTION 3: GAS SENSOR MODULE TECHNOLOGY OVERVIEW

LIST OF CONTENTS

Section Page

3.1 Pm Transducer Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3

3.2 Gfx 1210 Transducer Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6

3.3 Zirconia Transducer Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12

3.4 IR 1520 Transducer Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16

LIST OF FIGURES

Figure Page

3.1 Paramagnetic transducer schematic diagram . . . . . . . . . . . . . . . . . . . 3.3

3.2 Gfx 1210 transducer schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . 3.7

3.3 Zirconia cell cross section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12

3.4 1520 Block schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16


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3.2

NOTES


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3.4

The dumb-bell is slightly diamagnetic so that it takes up a position slightly awayfrom the most intense part of the magnetic field. When the surrounding gascontains oxygen then the oxygen molecules will be attracted into the strongestpart of the magnetic field. This pushes the dumb-bell further out of the magneticfield due to the relatively stronger force on the paramagnetic oxygen. The

magnitude of the torque acting on the dumb-bell will be proportional to theparamagnetism of the surrounding gases and hence proportional to the oxygenconcentration.

Servomex paramagnetic transducers incorporate a strong rare metal taut-bandsuspension mechanism onto which is mounted the dumb-bell (1). The "zero"position of the dumb-bell is sensed by a photocell assembly (4) which receiveslight from a mirror (2) attached to the dumb-bell. The output from the photocellis amplified (3) and fed back to a coil wound around the dumb bell so that thetorque acting upon it due to presence of oxygen in the sample is balanced by arestoring torque due to the feedback current in the coil.

The feedback current is directly proportional to the volume magneticsusceptibility of the sample gas and hence, after calibration, to partial pressureof oxygen in the sample. A voltage output is derived which is proportional to thecurrent. Linearity of scale also makes it possible to calibrate the instrument for all ranges by checking at two points only. For example accurate calibration isobtained by using pure nitrogen for zero and air for setting the span at 20.95 %.

All the materials in contact with the sample are highly resistive to aggressivecompounds. The internal design of the cell body has a special flow channel toimprove the flow characteristics, while the volume is kept to a minimum toprovide an excellent response time. The optical carrier (4) has provisions for moving of the photocell mount for setting the initial zero and also incorporatesthe LED light source and temperature sensing devices.

3.1.2 The Electronics

The control electronics perform all the functions necessary to provide operationof the transducer and to produce an electrical output proportional to the partialpressure of oxygen. Interfacing for inputs and output is via a 16 way IDC

connector, the electronic PCB includes the following circuit functions:

1. a constant current source2. the signal amplification/conditioning circuits3. the thermometer/signal conditioning circuits4. the span temperature compensation5. the output signal conditioning circuits6. a voltage reference7. the zero temperature compensation8. the kick circuit9. the negative supply generation

A short description of each circuit:


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3.5

The constant current source provides a constant current for the infrared LED.

The position of the test body (dumbbell) is detected by a pair of photocellsconnected in parallel opposition.

The current output of the photocells which is proportional to the deviation of thetest body from the null position is fed into the current amplifier. At the output of the amplifier a phase advance network ensures the stability of the servo system.

The test body assembly includes the feedback coil on the test body, thuscompleting the servo loop.

Where fitted, the thermometer/signal conditioning circuits include an electronicthermometer placed in close contact with the face of the transducer. Thethermometer supplies a current which is proportional to the absolutetemperature. This signal is used for zero temperature compensation.

The span temperature compensation relies on a thermistor and a resistancenetwork. It provides temperature compensation over a broad range of operatingtemperatures.

The output signal conditioning circuits provide temperature compensation andincorporates coarse and fine span adjustment and fine zero adjustment.

The voltage reference generates reference voltages of both positive andnegative polarity. These signals are used with the fine zero adjustment and thetemperature output circuits. They also provide an offset to the zero temperaturecompensation circuitry, thus ensuring the compensation signal level at thecalibration temperature is zero.

The zero temperature compensation is derived from the thermometer output.The level of compensation is factory set.

The kick circuit is only functional during power up. If the sample gas is pureoxygen and the power to the transducer is lost, some units will deflect to a pointwhere the reflected light beam does not fall onto the photocells. When power isrestored the kick circuit supplies an appropriate current in order to restore the

feedback control.

The negative supply circuit generates the negative supply rail required by theremaining circuitry.


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3.6

3.2 Gfx 1210 transducer module

3.2.1 Principles of operation

The Gfx 01210 is a Servomex Infrared Gas Filter Correlation transducer. A

number of versions are available to measure, for example, carbon monoxide(CO), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and sulphur dioxide (SO2).

The description which follows uses carbon monoxide as an example only.Everything stated applies equally to other measurements.

Like most pollutant gases carbon monoxide (CO) absorbs electromagneticenergy in the infrared spectrum. The amount of the IR absorbed provides ameasurement of the CO in the sample. Sensors utilising a band pass opticalfilter to select the wavelengths absorbed by CO are well known for the

measurement of percentage level CO samples. Their effectiveness for measuring low (vpm) levels of CO have been limited by the following factors.

1. Cross sensitivity to other IR absorbers.

Other gases in the gas stream (such as H2O and CO2) also absorb IR energy atthe same energy wavelengths as CO. This results in a cross sensitivity effect.

2. Drift.

Instability in the IR source and detection and contamination of the sample cellresult in changes in the transmitted IR energy measured. This baseline instabilityis observed as drift in the measured CO value.

The gas filter correlation technique resolves the weaknesses inherent in moretraditional IR absorption sensors. These weaknesses, including drift and crosssensitivity, are effectively eliminated by the use of gas filled filters. The IRabsorption spectrum of CO is not a smooth curve but consists of a number of distinct lines. So while at low resolution the IR spectra of CO and CO2 (for example) overlap, at high resolution they do not. Band pass optical filters withsufficient resolution are not generally available. Gas filled filters allow the

transducer to selectively remove only those IR wavelengths directly associatedwith CO.

Refer to figure 3.2

An infrared source (1) produces broad band infrared energy. A lens (2) is usedto provide a collimated IR beam that passes to the detector. A band pass IR filter (4) selects only those wavelengths in the IR spectrum that are absorbed by CO.


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3.7

Figure 3.2 Gfx 1210 transducer schematic diagram

Two small glass gas filled cells (cuvettes), one containing nitrogen (9) and theother one containing CO (3), are mounted on a wheel (8). A brush less DC motor (10) causes the wheel to rotate. As the wheel rotates the infrared beamalternately goes through the nitrogen filled filter and the CO filled filter. When thenitrogen filter is in position, no absorption takes place and all of the IR energypasses through to the sample gas cell and detector. When the CO filter is inposition, absorption takes place and the IR intensity of the wavelengthscharacteristic to CO is reduced.

The modulated IR beam passes through a gas filled sample cell (7) where someof the IR energy is absorbed. The remaining IR energy passes through acondenser light pipe (5). This concentrates the energy onto a pyrolytic infra reddetector (6). This measures the intensity of the IR beam.

The IR radiation that had passed through the nitrogen filter is significantlyattenuated when it passes through the sample gas containing CO. The radiationthat had passed through the CO filter is not significantly affected by the sample

gas containing CO because most of the energy at wavelengths characteristic toCO were already removed by the gas filled filter.

Sample gases containing CO2 or other IR absorbers attenuate the signal with thenitrogen and CO filled filters equally. Hence they have little effect on themeasurement.

Changes in source intensity or contamination of the sample cell also effect thesignals with the nitrogen and CO filled filters equally and again have little effecton the measurement.


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3.8

The value obtained by ratioing the difference between the nitrogen and gassignal with the gas signal is related to the CO gas concentration. Any changeswhich equally affect both nitrogen and CO signals will be cancelled by thisdesign.

3.2.2 The electronics

The Gfx 1210 consists of four main electronic assemblies:

The Infra Red Detector Pre-amp PCB

Refer to drawing 01210/901.

The Infra Red Detector Pre-amp PCB translates IR radiation into an analoguevoltage which can be further processed in order to extract the useful information.

IC3, a pyro-electric infra red (P.I.R.) sensor (figure 3.2[6]) responds to changesin infra-red radiation levels falling upon its sensing area. An output signalappears on pin 2 of IC3, which connects to R3 (IC3 load resistor), and a passivehigh pass filter formed by C3 and R4. C4 provides low pass filtering. Theresulting signal is then amplified by part of IC1, (a variable gain amplifier). Thegain of this stage can be set between 28 and 128 by adjusting RV1. Theamplified signal then passes to the second part of IC1, which is a precisiondifferentiator circuit. Output current is limited by R9, and C13 is for EMCprotection.

A stabilized supply for the P.I.R. detector is provided by using the Zener diodeD1 in a resistive divider circuit. C1 and C2 provide further filtering of the power supply for the P.I.R. detector.

The Signal Processing PCB


On the Signal Processing PCB the signal from the pre-amp PCB is sequentially

distributed to four sample and hold circuits. The averaged dark signal issubtracted from the averaged signals corresponding to nitrogen and CO. Theresulting nitrogen signal is subtracted from the CO signal and is providedtogether with the CO signal to the Xentra unit in order to work out the COconcentration.

The signal from the pre-amp board passes through a low pass filter LC2 andthrough R2 to IC5 pin 8, and one section of IC8, which is a unity gain buffer for TP1. This signal is sequentially distributed by IC5 to four averaging circuitscomprising IC6, C24, C25, C26 and C27. These averaged signals are "DNIT"(dark nitrogen), "LNIT" (light nitrogen), "DGAS" (dark gas) and "LGAS" (light

gas), which are differentially processed to remove the common mode "dark"signals from "LNIT" and "LGAS". Low pass filtering and gain adjustment isprovided by two sections of IC8, and the outputs are Vnitrogen and Vgas. C5 and C3


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3.9

provide EMC protection, and these signals are sent to the "MAST" connector.The remaining section of IC8 produces a difference signal from Vnitrogen and Vgas,named Vdiff and this signal is sent to the MAST connector through low pass filter LC7.

IC5 is a DPG508A analogue multiplexer and IC6 is a AD704 quad op-ampconnected to form two difference amplifiers with high impedance inputs. IC5samples the light and dark signals for CO and nitrogen while the differenceamplifiers subtract the dark signals from the light signals to provide the Vgas andVnitrogen signals. R3, C4 and IC8 pin 5, 6 and 7 provide low pass filtering for theoutput Vnitrogen.R4, C2 and IC8 pin 1, 2 and 3 provide low pass filtering and avariable gain buffer. SW1 and RV1 provide coarse and fine gain adjustment for transducer calibration. The output Vgas is calibrated to be equal with Vnitrogen whenthe sample gas does not contain any CO.

RN4 and IC8 pin 12, 13 and 14 provide a variable gain difference amplifier. The

value of R14 (430 ohms) was selected in order to provide a 1 volt for Vdiff whenthe sample concentration is 500 ppm CO.IC8 pin 8, 9 and 10 provides a buffer for the diagnostic output TP1. This signalshows all four sampled and averaged signals superimposed on the input signalreceived from the pre-amp PCB

The Housekeeping PCB


The Housekeeping PCB provides the required voltages for the chopper wheelmotor and for the IR source. In order to avoid the effects of the ambienttemperature on the CO concentration, the chopper box and the signalprocessing board are kept at a constant temperature of 70C. The PID heater control system is located on the housekeeping PCB. On this PCB are alsolocated the digital circuits which provide the logic for the sequential distributionof the four sample and hold circuits.

IC1 forms a P.I.D. chopper box heater control system. The temperature issensed by a thermistor connected to PL1 pin 18 and 20, which in conjunction

with R1 and R2 form a resistive voltage divider. C2, R94 and IC1 pin 1, 2 and 3are wired in a differentiator configuration in order to produce an output signalproportional with the rate of change of the thermistor resistance. The outputsignal is summed with the main thermistor signal to produce error rate damping.The sum of these two signals is used as input for the other half of IC1 wired inan integrator configuration. The output of this integrator (pin 7 of IC1) will changeas long as the voltage on pin 18 PL1 is different in respect with the reference of 2.5 volts. When the power is switched on the resistance of the thermistor is highand in consequence the voltage on pin 18 PL1 will be lower than 2.5 volts. Acurrent will flow through R8 which will charge C4 and the integrator outputvoltage will increase. This will have, as an effect, an increase in power applied

to the chopper box heaters. Once the thermistor sees a temperature close to65C, the voltage on pin 18 PL1 will become approximately zero, the integrator output voltage will not increase any more and the power applied to the heaters


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3.10

will remain constant. Any change in the thermistor's resistance will the changethe power applied to the heaters in order to keep the chopper box temperatureconstant.

Transistor TR1 limits the integrator output range and results in faster

temperature stabilisation by preventing unnecessary voltage swings after theoutput transistor is saturated.

The two sections of IC2 are unity gain buffers for the AD590 temperaturesensors on the IR detector pre-amp and chopper box.

The ICs 4,5,6 and 7 form a standard configuration for hall effect commutatedbrush less motors. Passive low pass filters have been added to the Hall inputsto prevent EMC inducing spurious commutation. IC6 is the motor driver IC andIC7 is the phase locked loop motor speed controller. Speed errors are detectedand signalled by IC7. IC4, TR4 and IC13 use this error signal to disable the

instrument and measurements during incorrect motor operation. The D14 greenLED is switched on when the motor is in synchronisation.

The ICs 8, 9, 10, 11, 12, and TR's 2, 3, 5 and 6 form a switched mode supply for the Infra red source. IC10 is a switched mode controller. Passive low pass filtersadded to the voltage and current sense inputs on IC10 are for EMC suppression.R82, TR5 and TR6 detect and open circuit failure or a malfunction of theswitched mode power supply. If errors are detected, IC13 sends the fault signalto the MAST connector. IC11 and IC12 perform voltage sensing andprogramming and the D11 green LED is used to signal a malfunction of theswitched mode power supply.

The switch SW1 is used to change the IR source voltage. For the 1210transducer SW1 is set to position 5 in order to have a source voltage of 2.0 volts.

The D15 green LED is used to signal that the power supply is on and the D16green LED is used to signal that the transducer is in working order. Amalfunction of the switch mode power supply, a motor which is not insynchronisation or a problem with power supply from Xentra unit will switch off the D16 green LED.

The ICs 14, 15, 16 and 17 provide the digital logic required for the analoguemultiplexer from the signal processing PCB. IC14 provides a 16 MHz clock for the EPLD (IC16). The synchronisation signal from the optical sensor providesinformation in respect to the disk position. Inside the EPLD this signal isprocessed in order to implement the address lines A1 and A0 and an enablesignal for the analogue multiplexer. IC15 and IC16 are used as frequencydividers.

IC18, a serial EEPROM circuit is programmed by the Xentra unit and stores thelinearisation information required for the calibration of the 1210 transducer.


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3.11

The Chopper Box PCB


The Chopper Box PCB provides the interface between the motor and the

housekeeping board. The optical sensor which generates the synchronisationsignals from the chopper wheel is also located on this board.

A slotted optical sensor is used to detect slots around an interrupter disc. Thesignal provided by the optical sensor is used to synchronise the analoguemultiplexer. The board also includes the motor interface and a AD590temperature sensor.


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3.12

Figure 3.3 Zirconia Cell Cross Section

3.3 Zirconia transducer module

3.3.1 Principle of operation

The Servomex (R) zirconia sensor (Figure 3.3) is manufactured using yttriastabilised zirconia. When this material is heated to a temperature above 600°Cit will conduct oxygen ions. The oxygen ion conductivity increases exponentiallywith temperature. The sensor consists of a disc of yttria stabilised zirconiamounted in a tube of the same material. The faces of the disc are coated withplatinum and the assembly is mounted in a small temperature controlled tubular oven.

When the two sides of the disc are exposed to gases containing oxygen, aconcentration cell is formed and an electrical output proportional to the logarithmof the ratio of the oxygen concentrations on each side of the disc is obtained.

(When the concentration is the same on both sides of the disc the logarithm of the ratio is 0.)

The fact that the oxygen content of air is very constant at 20.95% makes itconvenient to use air as the reference gas which is applied to one side of thedisc while the sample is applied to the other side.


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3.13


Functional Distribution

The Board provides the following two key areas of functionality:-

Cell temperature control Cell output amplification.Operation of these areas of the circuit are described in more detail below.

Cell Temperature Control

The Zirconia housekeeping board provides all of the circuitry necessary tomaintain the zirconia cell at its correct operating temperature. Heater power tothe cell is derived from the AC MAST power connector and is switched under closed loop control. The circuit incorporates a soft start feature to reduce thermal

shock to the cell, and limits power delivered to the cell under fault conditions.These circuits are described in more detail:-

Thermocouple Amplifier

The cell thermocouple connects to terminal block TB1. Copper ground planesrun under the thermocouple amplifier IC1 to improve EMC. IC1 contains the cold junction compensation.

The temperature of the thermocouple can be found by measuring the voltage on

test point TP1 with respect to TP3 and using the table from the AD595 datasheet.

If the thermocouple is open circuit or reverse connected IC1 pin 12 is pulled lowto inhibit the heater circuit.

The cell temperature is set by RV1 in conjunction with LK2 and LK3. TheZirconia electrode temperature is available for Nernst equation calculations atPL2 pin 12. The temperature error amplifier IC3 pin 14 has an output of 2.2V/Cwhich drives the heater controller.

Variable resistor RV2 in conjunction with LK1 compensates for the temperaturedifference between the Zirconia electrode and the thermocouple. RV2 isadjusted at the time of test to give the correct cell temperature indicationdetermined by the Nernst equation.

Heater Voltage Measurement

The circuit around IC3 pin 1 rectifies the heater voltage pulses. The polarity of the AC input is detected by IC6 pin 2 and is used to control the sign of the gain

of amplifier IC3.


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3.14

Heater Power Measurement

The positive heater pulses are converted into a current by R30 and then drawnthrough two base-emitter junctions by IC3 pin 7. The voltage on IC5 pin 3 isapplied to two more base-emitter junctions, one of which has a constant bias

from R21.

Due to the logarithmic characteristic of the base-emitter junctions, the currentdrawn into the collector of IC5 pin 5 is proportional to the square of the currentin R30. This circuit therefore measures the heater voltage and produces acurrent proportional to the heater power.

Soft Start

Initially C24 is uncharged, so holding TR3 drain low. The current drawn throughR14 limits the initial heater power.

As C24 charges up, the current through R14 drops and the power limitincreases.

Heater Driver

The heater demand (current in R12) is subtracted from the heater power (current

in IC5 pin 5) and integrated by C25.

When the voltage on IC3 pin 8 drops to zero the comparator IC6 pin 13 goeshigh to enable another heater pulse.

Zero Crossing Switch

The comparator IC6 pin 14 senses the two AC inputs and pulls low to inhibitheater pulses except when the AC is near a zero crossing point.

Full Cycle Heater Pulses

The comparator IC6 pin 1 has hysteresis to provide a clock to IC10 pin 3 whichis connected as a divide by 2. This signal is used to clock IC10 pin 11 on eachmains cycle.


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3.15

Heater Output

Transistor TR2 drives the two triacs which supply a symmetrical voltage to theheater. When the heater is not driven, resistors R18 and R19 pull the heater toground.

The gain of the heater controller from IC3 pin 14 is approximately 5W/V and thegain from the thermocouple to the heater is approximately 11W/V.

Cell Signal Amplifier

The cell is connected to an instrumentation amplifier IC9 which can be set to again of 1 or 10.

The output of the instrumentation amplifier is referenced to IC9 pin 10. Thisvoltage is controlled by IC2 pin 8 which allows the cell offset voltage to beremoved by adjusting RV3. An external variable resistor connected to TB1 canalso be used to remove the cell offset voltage.

The cell amplifier can be linked to have a bipolar output, where the air point isat zero voltage output. The amplifier can also be linked to have a unipolar outputwhere the air point is set to a positive bias voltage.

The air point reference is available on PL2 pin 13 so that a differentialmeasurement can be made to remove any variation in the bias voltage.

The output buffer can be linked to have a gain of 1 or 2.3.


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3.16

Figure 3.4 1520 Block schematic

3.4 IR 1520 transducer module

The 1520 family of infrared transducers offer percentage measurements of carbon dioxide, carbon monoxide or methane. Based upon the single beam,single wavelength technique, wavelength selection is achieved by a carefully

specified narrow band interference filter. The length of the sample cell dependson the sample gas and concentration to be measured. The sample cell, sourceunit and detector unit is maintained at a constant temperature.

3.4.1 Principles of operation

Refer to the block diagram given in Figure 3.4. The infrared source is pulsed at8Hz to give an infrared carrier signal which is attenuated by the sample gas, anda detection system which will convert this attenuation into an electrical output.

The transducer comprises of a sensor and a Main Board and is supplied witheither an on-board sensor or an off-board sensor. The configuration dependson the gas and range to be measured.

The off-board sensor configuration has a long path length sensor. Thesesensors are installed off the board using the two interconnecting cables suppliedwith each unit. These variants have a higher power consumption.

Each transducer is calibrated for a fixed range of a specific gas, giving an outputof nominally 0 to 1V dc full scale at TP3. A second low integrity live-zero outputindicates the actual intensity of the infrared carrier signal at TP5.


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3.17

3.4.2 The Sensor

The sensor is an optically aligned, gas tight enclosure having good thermaltransfer. The sensor comprises of three main sections, namely the sample cell,the source unit and the detector assembly.

Sample Cell

The sample cell forms the central section of the sensor. The sample cell is fittedwith sapphire windows and O rings at each end, which give gas tight sealing andalignment for the source and detector units. Sample cells of between 1mm and160mm in length are used, depending on variant, giving an internal volume of between 10l and 2000l.

The cell is fitted with two 1/8" OD stainless steel stub fittings, to which can be

attached flexible tubing or a compression fitting for rigid tubing. The fittings maybe replaced when damaged.

Source unit

The source unit comprises of an infrared source, a source holder, a mountingboard, and an O ring.

The infrared source is a patented Servomex design, and is enclosed in a fullysealed TO5 can assembly. The TO5 can incorporates a narrow band opticalfilter, and the source unit will only transmit energy defined by this optical filter.

Detector unit

The detector unit is a fully integrated, sealed assembly comprising of a solidstate detector, a heater, a thermistor and an Interface PCB. The long pathlength variants also include a second heater and thermistor.


The electronics consist of a control section, a detector pre-amplifier; ademodulation section, a signal scaling section and a housekeeping PCB.

Control Section

The control section on the Main Board incorporates a daughter pcb and providesall the necessary functions for pulsing of the infrared source and temperaturecontrol of the sensor. An auxiliary temperature control circuit is populated in the

off-board sensor configuration only.


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3.18

Detector Pre-Amplifier

The detector pre-amplifier section is incorporated into the Interface PCB on thesensor, and connects to Main Board through a 9 way 'D' type male and femaleconnector.

The pre-amplifier takes the small amplitude modulated 8Hz carrier signal fromthe infrared detector and processes it to give an amplified output suitable for demodulation purposes.

Demodulation Section

The demodulation section on the Main Board comprises of a constant amplitudephase adjustment network, a full wave synchronous detector controlled by thesource drive and an active low pass filter. The output from this section is a

rectified positive signal which is the mean value of the original input carrier signaland is a measure of the transmitted IR energy as modulated by the sample gas.

Signal Scaling

The signal scaling section on the Main Board accepts inputs from thedemodulation section and the negated band gap (zero gas) reference. Thesesignals are adjusted to a null zero condition at the input to the scaling amplifier by the zero control. Any change in the rectified carrier signal is now amplified toprovide signal scaling. The gain depends on the range and gas being measuredand is pre-selected by LK1-3. RV3 is adjusted in order to provide a 1 volt outputat span. The difference signal then passes through an active low pass filter andthe output at TP3 is Vdiff .

The 2.5V rectified carrier signal is routed via the housekeeping pcb to IC3 whereit is attenuated to 0.9V (RV2 always CCW) and HF filtered and the output at TP5is Vsig.

Housekeeping PCB

This board acts as the interface between the 1520 and the Xentra chassis. Itroutes power to the relevant sections of the transducer and relays the transducer signals to the Xentra via the MAST connector. The 1520 power is supplied by a15W +5V switching regulator operating at 500kHz and is derived from auxiliaryMAST 18-0-18V AC power.

The nominally ±5V 1520 diagnostic signals for Vref , -5V, warm-up and heater power are attenuated and/or clamped by interface circuitry to less than +1V andsent to the MAST connector. The multiplexer itself clamps any signals


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3.19

The rectified carrier signal of the 1520 is routed back to the Main Board via R2for attenuation before returning to the housekeeping pcb as Vsig. Vdiff is filteredthrough a HF low pass filter R1,C1.

3.4.4 Drift and lo calibration

Instability in the IR source and detection and contamination of the sample cellresult in changes in the transmitted IR energy measured. This baseline instabilityis observed as drift in the measured value.

This weaknesses is effectively eliminated by frequent lo calibration in which themeasurement is scale corrected for the actual change in transmitted IR energy.

When the user invokes any lo calibration and in particular an auto-zero

calibration the Xentra notes the value of Vsig and scale corrects the current andsubsequent measurements of Vdiff for the drift in Vsig. This provides a live-zeroreference for Vdiff while maximising signal integrity.


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3.20

NOTES


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4.1

SECTION 4: SPARES LIST

LIST OF CONTENTS

Section Page

4 Spares List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3

4.1 Xentra Chassis / General Spares . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3

4.2 Circuit Boards and Electrical Spares . . . . . . . . . . . . . . . . . . . . . . . . 4.4

4.3 Sample System Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6

4.4 Paramagnetic Transducer Module Spares . . . . . . . . . . . . . . . . . . . 4.7

4.5 Gfx 1210 Transducer Module Spares . . . . . . . . . . . . . . . . . . . . . . . 4.8

4.6 Zirconia Transducer Module Spares . . . . . . . . . . . . . . . . . . . . . . . . 4.9

4.7 IR 1500 Series Transducer Module Spares . . . . . . . . . . . . . . . . . 4.10

4.8 Recommended Spares List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.11

IMPORTANT NOTE:

All ‘complete’ spare Gfx 1210 and IR 1500 series transducers are suppliedcalibrated in a nitrogen background.

If this does not meet the original ‘as supplied’ application requirements(eg: in a 4210), inform Servomex at time of order.


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4.2

NOTES


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4.3

4 SPARES LIST

4.1 Xentra Chassis / General Spares

PART

NUMBER DESCRIPTION COMMENTS

04000003C QUICKSTART MANUAL (ENGLISH)

04000013C QUICKSTART MANUAL (FRENCH)

04000023C QUICKSTART MANUAL (GERMAN)

04000033C QUICKSTART MANUAL (SPANISH)

04000005C INSTALLATION MANUAL (ENGLISH)

04000015C INSTALLATION MANUAL (FRENCH)

04000025C INSTALLATION MANUAL (GERMAN)

04000035C INSTALLATION MANUAL (SPANISH)

S4000976 KIT, FEET TIP UP, GREY four feet with fixing screws

S4000980 KIT, FRONT FASCIA ASSY (Figure 6.2 [29]) Includes Windowand gasket already installed,flowmeter covers and blanks, labelsand sample filter blank withadhesive

S4000983 KIT, FAN REPLACEMENT Use for external (Figure 6.6 [1]) or internal fan (Figure 6.7 [2])

2388-1981 FILTER ELEMENT, FAN (Figure 6.6 [4])

S4000984 RACK MOUNT KIT,SHORT CHASSIS See operators manual

S4000985 RACK MOUNT KIT, LONG CHASSIS See operators manual

S4000424 RACK MOUNTING BRACKETS (EARS) See operators manual

2322-1020 EMC CONDUCTIVE GASKET (Figure 6.3 [1]) or (Figure 6.2 [31])

3912-8010 KEYMAT MOULDING (Figure 6.2 [22])


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4.4

4.2 Circuit Boards and Electrical Spares

PART

NUMBERDESCRIPTION COMMENTS

S2000902A PROCESSOR BOARD (Figure 6.4 [6])Does not include firmware

S4000652 FIRMWARE (4000C GENERIC) (Figure 7.1 [4,5])

02000906A OPTION CARD: 2 x mA and 3 x relays (Figure 6.4 [2,3,4])

Direct replacement for 02000906

and substitute for 02000907

02000924 SENSOR INTERFACE PCB (Figure 6.4 [7])

Direct replacement for 02000914

S4000901 MOTHERBOARD (Figure 6.9 [9])

S4000903 KEYPAD PCB (Figure 6.2 [21]). For use with04000932 display module only

2822-8019 INVERTOR 24 VDC TO 600 V (Figure 6.2 [41])

S4000903A KEYPAD PCB (Figure 6.2 [21]). For use with

04000925 display module only

S4000904 TERMINAL BOARD (Figure 6.9 [6])

S4000907 EXT. AUTOCAL P.C.B. ASSY (Figure 6.5b [8])

S4000924 MULTIPLEXER PCB, 4 TX (Figure 6.4 [1])

04000925 DISPLAY + RIBBON ASSEMBLY (LCDwith Green LED baclight)

(Figure 6.2 [24]) Includes lamp.

S4000932 DISPLAY + RIBBON ASSY (Blue/WhiteLCD with CCFL backlight)

(Figure 6.2 [24]) Includes lamp.

S4000932A CCFL BACKLIGHT ASSEMBLY FORBLUE/WHITE DISPLAY

(Figure 6.2 [24])

S4000933 KIT, KEYPAD RIBBON CABLE (Figure 6.3 [2]) includes ribbon cableclamps [9] and grommet [7]

S4000977 KIT, FUSE PCB Includes :5 off 'T' 500 mA for F2 on rear of

chassis

20 off 5A PCB fuses (Figure 6.8 [2])for F1 to F8 on Multiplexer board.

S4000978 KIT, FUSE MAINS 170-264V 10 off 3.15A 20mm 'T' HBC

S4000979 KIT, FUSE MAINS 85-132V 10 off 5.0A 20mm 'T' HBC

S4000936 IEC MAINS FILTER INLET (Figure 6.4 [9, 11]

Does not include fuses. SeeS4000978 and S4000979 above.

S4000986 KIT, SOCKET 14W SIGNAL See operators manual

4911-6034 SWITCHED MODE POWER SUPPLY (Figure 6.4 [19])


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4.5

4911-6027 SWITCHED MODE POWER SUPPLY

MUST BE USED IN 4200 & 4210

ANALYSERS

(Figure 6.4 [19])

4961-1159 TRANSFORMER 4 TRANSDUCER (Figure 6.4 [17]) Includes rubber mat

4961-1166 TRANSFORMER 2 TRANSDUCER (Figure 6.4 [17]) Includes rubber mat


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4.6

4.3 Sample System Spares

PART


S4000974 KIT, SOLENOID VALVE (Figure 6.5a [2,9])

04000423 CALIBRATION MANIFOLD (Figure 6.5a [1])

S4000975B TUBING / FITTINGS REFURB. KIT Includes fittings and adaptors

S4000982 50-500 ml/min FLOWMETER (Figure 6.2 [9,10]) Includes 'o' rings

S4000971 50-2500 ml/min FLOWMETER (Figure 6.2 [9,10]) Includes 'o' rings

S4000981 500 - 5000 ml/min FLOWMETER (Figure 6.2 [9,10]) Includes 'o' rings

S4000954 KIT, NEEDLE VALVE, FLOWMETER

S4000987 KIT, FINE FILTER CAP (Figure 6.2 [32]) Includes 'o' ring

S4000988 KIT, FILTER ELEMENTS 6 (Figure 6.2 [33])

01131434 STUD COUPLING MOD 1/8"BSPTM

2344-0027 COUPLING 1/8"OD (F) SS SWAGELOK

2377-3831 EXTERNAL STAINLESS STEEL FILTERUNIT, COMPLETE

See section 2.2.16

2377-3848 SPARE ELEMENT FOR ABOVE

2383-1621 RESTRICTOR 0.006" (RED)Used on: 4100/4200 seriespressure driven Basic Pm module

2383-1638 RESTRICTOR 0.010" (CREAM)

Used on: 4100/4200 seriespressure driven Control / Purity Pm& I.R. modules.Used on: 4900 series Basic Pmmodule

2383-1607 RESTRICTOR 0.012" (BLACK)Used on: 4900 series Control Pmand I.R. modules

2383-1669 RESTRICTOR 0.020" (BLUE)Used on: 4900 series bypassnon-Gfx streams

2383-1676 RESTRICTOR 0.025" (BROWN)Used on: 4100/4200 series pressure

driven Pm & I.R. modules.

2383-1683 BYPASS NEEDLE VALVE (INTERNAL)Used on: 4900 seriesnon-Gfx streams


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4.7

4.4 Paramagnetic Transducer Module Spares

PART


00325000 PARAMAGNETIC CELL

04200901 BARRIER PCB MUST BE USED ON 4200 & 4210

ANALYSER PARAMAG. MODULE

01111E701 PARAMAGNETIC TRANSDUCER

01158000 PARAMAGNETIC TRANSDUCER (Figure 6.14 [17])

S1166901 PRESSURE TRANSMITTER PCB (Figure 6.14 [13])

S4100902 PARAMAGNETIC MODULE HEATERPLATE

(Figure 6.14 [19])

S4100995A PURITY PARAMAGNETIC SENSORMODULE, TEMP. CONTROLLED WITHPRESSURE SENSOR.

(Figure 6.14)

S4000990 1158 CONTROL PARAMAGNETIC GASSENSOR MODULE

(Figure 6.15)

S4000991 1158 CONTROL PARAMAGNETIC GASSENSOR MODULE, PUMP SPACE

S4000992 1111E701 BASIC PARAMAGNETIC GASSENSOR MODULE

S4000993 1111E701 BASIC PARAMAGNETIC GASSENSOR MODULE, PUMP SPACE

S4200990 1158 INTRINSICALLY SAFE CONTROLPARAMAGNETIC GAS SENSORMODULE


ANALYSERS

04000937C RIBBON CABLE ASSY 500mm Used on modules 3 & 4

04000937E RIBBON CABLE 250mm Used on modules 1 & 2

01156922 CELL TUBE, PARAMAG MODULE 2 required per paramag module


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4.8

4.5 Gfx 1210 Transducer Module Spares

PART


S1200923 SCRUBBER ASSEMBLY (Figure 6.19 [5])

S1210501 KIT SCRUBBER SACHET (Figure 6.17 [34]

S1210701 GFX TRANSDUCER - CO,HIGH SENSITIVITY

See section 6.30

All ‘complete’ spare Gfx 1210

transducers are supplied

calibrated in a nitrogen

background.

If this does not meet the original

‘as supplied’ application

requirements(eg: in a 4210), inform Servomex

at time of order.

S1210702 GFX TRANSDUCER - CO,STANDARD SENSITIVITY

S1210712 GFX TRANSDUCER -SO2

S1210721 GFX TRANSDUCER - NO

S1210731 GFX TRANSDUCER - CO2

S1210741 GFX TRANSDUCER - N2O

S1210751 GFX TRANSDUCER - CH4

S1210901 KIT, DET. PRE-AMP ASSEMBLY See section 6.37

S1210902 KIT, SIGNAL P.C.B. See section 6.40

S1210904 KIT, CHOPPER BOX P.C.B. See section 6.38

01210905A KIT, HOUSEKEEPING P.C.B. See section 6.39

S1210922A GAS CELL ASSEMBLY (LONG) See section 6.36

S1210922B GAS CELL ASSEMBLY (SHORT) See section 6.36

S1210923 KIT, I.R. SOURCE See section 6.31

S1210996 KIT, 1210 FUSES Includes thermal fuse

S1210997 KIT, OPTICAL WINDOWS See section 6.35

S1210998 KIT, OPTICAL MIRROR See section 6.34

S1210999 KIT, MOTOR ASSEMBLY See section 6.32

04000934B RIBBON CABLE ASSY, 550mm Used on Modules 1 & 3

2527-3034 MODULE POWER CABLE ASSY Used on Modules 1 & 3

S4100925 RESTRICTIVE T ASSEMBLY (GFX) (Figure 6.22 [4])

04100408 PIPE: STUB LOW PRESSURE BYPASSOUTLET

Used on pressure driven sampleoption for 4100 & 4200

04100435 INLET TUBE, GFX MODULE 1 See section 6.42

04100436 INLET TUBE, GFX MODULE 3 See section 6.42

04100437 OUTLET TUBE, GFX Used on 4100, 4200 & 4900


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4.9

4.6 Zirconia Transducer Module Spares

PART


S0700912 ZIRCONIA HOUSEKEEPING PCB (Figure 6.10 [11])

00703000 ZIRCONIA SENSOR (Figure 6.10 [6])

00704000 ZIRCONIA SENSOR, LOW ACTIVITY (Figure 6.10 [6])

04000934A RIBBON CABLE ASSY, 300mm Used on Modules 1 & 2

04000934B RIBBON CABLE ASSY 550mm Used on Modules 3 & 4

2527-3034 POWER CABLE ASSY, 350mm Used on Modules 1, 2 & 3

2527-3041 POWER CABLE ASSY, 465mm Used on Module 4

S4100924 RESTRICTIVE TEE ASSEMBLY (Figure 6.11 [1])

S4100993 ZIRCONIA GAS SENSOR MODULE 703CELL

(Figure 6.10 )

S4100994 ZIRCONIA GAS SENSOR MODULE 704CELL

(Figure 6.10 )

00700922 INLET PIPE ASSY, ZIRCONIA CELL (Figure 6.10) [4]


Used on pressure driven sampleoption for 4100

04100431 PIPE: ZR MODULE 1 INLET See section 6.21





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4.10

4.7 IR 1500 Series Transducer Module Spares

PART


S1500355 GAS CONNECTOR KIT (x2) One required per transducer

01500923 EXTENDER RIBBON CABLE Used on off-board sensors

2531-2298 FUSE, 2.5A QAHBC (Figure 6.24 fitted to [3])

S4000921 I.R. INTERFACE P.C.B. (Figure 6.24 [3])

S4000950A I.R. TRANSDUCER MODULE 100% CO2 (Figure 6.24 [complete])

All ‘complete’ spare IR 1500

series transducers are supplied

calibrated in a nitrogenbackground.

If this does not meet the original

‘as supplied’ application

requirements

(eg: in a 4210), inform Servomex

at time of order.

S4000950B I.R. TRANSDUCER MODULE 50% CO2

S4000950C I.R. TRANSDUCER MODULE 25% CO2

S4000950D I.R. TRANSDUCER MODULE 10% CO2

S4000950E I.R. TRANSDUCER MODULE 5% CO2

S4000950F I.R. TRANSDUCER MODULE 2.5% CO2

S4000950G I.R. TRANSDUCER MODULE 100% CH4

S4000950H I.R. TRANSDUCER MODULE 50% CH4

S4000950J I.R. TRANSDUCER MODULE 25% CH4

S4000950M I.R. TRANSDUCER MODULE 50% CO

S4000950N I.R. TRANSDUCER MODULE 25% CO

S4000950P I.R. TRANSDUCER MODULE 10% CO

S4000950S I.R. TRANSDUCER MODULE 1% CO2

S4000950T I.R. TRANSDUCER MODULE 5% CH4

S4000950V I.R. TRANSDUCER MODULE 5000vpmCO2

S4000950W I.R. TRANSDUCER MODULE 2500vpmCO2

S4000950X I.R. TRANSDUCER MODULE 2.5% CO

S4000950Y I.R. TRANSDUCER MODULE 1% CO


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4.11

4.8 Recommended Spares List

PART

NUMBERDESCRIPTION

NUMBER OF ANALYSERS

1 - 3 4 - 9 10+

Chassis/General Spares

2388-1981 FILTER ELEMENT, FAN 1 2 3

Circuit Boards and Electrical Spares

S2000902A PROCESSOR BOARD 0 0 1

02000906A OPTION CARD: 2 x mA and 3 x relays 0 0 1

02000924 SENSOR INTERFACE PCB 0 1 1

S4000903 KEYPAD PCB

For analysers with CCFL backlightsonly

0 0 1

2822-8019 INVERTOR 24 VDC TO 600 V

For analysers with CCFL backlights

only

0 1 1

S4000903A KEYPAD PCB

For analysers with Green LED

backlights only

0 0 1

S4000924 MULTIPLEXER PCB, 4 TX 0 0 1

04000925 DISPLAY + RIBBON ASSEMBLY (LCD

with Green LED backlight)

0 1 1

S4000932 DISPLAY + RIBBON ASSY (Blue/WhiteLCD with CCFL backlight)

0 0 1

S4000932A CCFL BACKLIGHT ASSEMBLY FORBLUE/WHITE DISPLAY

2 4 6

S4000977 KIT, FUSE PCB 1 2 3

S4000978 KIT, FUSE MAINS 170-264V 2 4 6

S4000979 KIT, FUSE MAINS 85-132V 2 4 6


4100 & 4900 MODELS ONLY

0 1 1



ANALYSERS

0 1 1

4961-1159 TRANSFORMER 4 TRANSDUCER 0 0 1

4961-1166 TRANSFORMER 2 TRANSDUCER 0 0 1


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4.12

PART

NUMBERDESCRIPTION

NUMBER OF ANALYSERS

1 - 3 4 - 9 10+

Sample System Spares

S4000954 KIT, NEEDLE VALVE, FLOWMETER

For Model 4900 only

1 2 2

S4000975B TUBING / FITTINGS REFURB. KIT 0 1 1

S4000987 KIT, FINE FILTER CAP

For analysers with Internal Filter only

1 2 2

S4000988 KIT, FILTER ELEMENTS 6

For analysers with Internal Filter only

2 4 6

2377-3848 SPARE ELEMENT FOR EXTERNALSTAINLESS STEEL FILTER

For Zirconia transducers only

2 4 6

2383-1683 BYPASS NEEDLE VALVE (INTERNAL)

For Model 4900 analysers only which

are not fitted with Gfx transducers

1 1 1


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4.13

PART

NUMBERDESCRIPTION

NUMBER OF TRANSDUCERS

1 - 3 4 - 9 10+

Paramagnetic Transducer Spares

00325000 PARAMAGNETIC CELL 0 1 1

04200901 BARRIER PCB

For 4200/4210 models only

0 0 1

01111E701 PARAMAGNETIC TRANSDUCER

Basic Oxygen module

0 0 1

01158000 PARAMAGNETIC TRANSDUCER

For Oxygen Control/Purity modules

only

0 0 1

S1166901 PRESSURE TRANSMITTER PCBFor Oxygen Purity modules only 0 0 1

S4100902 PARAMAGNETIC MODULE HEATERPLATE

For Oxygen Purity modules only

0 1 2

Gfx 1210 Transducer Module Spares

S1200923 SCRUBBER ASSEMBLY 1 2 3

S1210501 KIT SCRUBBER SACHET 2 4 6

S1210901 KIT, DET. PRE-AMP ASSEMBLY 0 0 1

S1210902 KIT, SIGNAL P.C.B. 0 0 1

S1210904 KIT, CHOPPER BOX P.C.B. 0 0 1

01210905A KIT, HOUSEKEEPING P.C.B. 0 1 1

S1210923 KIT, I.R. SOURCE 1 1 2

S1210996 KIT, 1210 FUSES 1 2 3

S1210999 KIT, MOTOR ASSEMBLY 0 1 2


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4.14

PART

NUMBERDESCRIPTION

NUMBER OF TRANSDUCERS

1 - 3 4 - 9 10+

Zirconia Transducer Module Spares

S0700912 ZIRCONIA HOUSEKEEPING PCB 0 1 2

00703000 ZIRCONIA SENSOR 0 1 1

00704000 ZIRCONIA SENSOR, LOW ACTIVITY 0 1 1

00700922 INLET PIPE ASSY, ZIRCONIA CELL 0 1 2


0 0 1

04100431 PIPE: ZR MODULE 1 INLET 0 0 1




IR 1500 Series Transducer Module

Spares

S1500355 GAS CONNECTOR KIT (x2) 0 0 1

01500923 EXTENDER RIBBON CABLE 0 0 1

2531-2298 FUSE, 2.5A QAHBC 2 4 6

S4000921 I.R. INTERFACE P.C.B. 0 1 2


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5.1

SECTION 5: FAULT FINDING

LIST OF CONTENTS

Section Page

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3

5.2 Xentra Chassis Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5

5.3 Paramagnetic O2 Purity Transducer Faults . . . . . . . . . . . . . . . . . . . . . 5.14

5.4 Paramagnetic O2 Control Transducer Faults . . . . . . . . . . . . . . . . . . . . 5.20

5.5 Paramagnetic O2 Basic Transducer Faults . . . . . . . . . . . . . . . . . . . . . 5.25

5.6 Zirconia Transducer Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.30

5.7 1210 Gfx Transducer Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.35

5.8 IR 1520 Series Transducer Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.42

LIST OF FIGURES

Figure Page

5.1 Display not illuminated fault tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Xentra 4100 Service

Documents

Transcript of Xentra 4100 Service