Ametek Thermox Series 2000 WDG-IVC User manual

Thermox

®

Series 2000

WDG-IV, WDG-IVC, WDG-IVCM

User Manual

Thermox

150 Freeport Road

Pittsburgh, PA 15238

PN 90269VE , Rev. Y

This manual is a guide for the use of the Thermox Series 2000 WDG-IV (IVC / IVCM). Data herein has been veried and validated and is

believed adequate for the intended use of this instrument. If the instrument or procedures are used for purposes over and above the capabilities

specied herein, conrmation of their validity and suitability should be obtained; otherwise, AMETEK does not guarantee results and assumes no

obligation or liability. This publication is not a license to operate under, or a recommendation to infringe upon, any process patents.

Ofces

USA - Pittsburgh

150 Freeport Road

Pittsburgh, PA 15238

Ph. 412-828-9040

Fax 412-826-0399

CHINA

AMETEK Shanghai (SPL)

Room 408, Metro Tower

#30 Tian Yao Qiao Road

Shanghai 200030

Ph. 86 21 6426 8111

Fax 86 21 6426 7054

USA - Delaware

455 Corporate Blvd.

Newark, DE 19702

Ph. 302-456-4400

Fax 302-456-4444

AMETEK Beijing

CITIC Building, Room 2305

19, Jianguomenwai Dajie

Beijing 100004

Ph. 86 10 8526 2111

Fax 86 10 8526 2141

USA - Texas

4903 West Sam Houston Parkway North

Suite A-400

Houston, TX 77041

Ph. 713-466-4900

Fax 713-849-1924

FRANCE

AMETEK Precision Instruments France

Rond Point de l’épine des champs

Buroplus Bat D

78990 Elanbourt

Ph. 33 1 30 68 89 20

Fax 33 1 30 68 89 29

CANADA

2876 Sunridge Way N.E.

Calgary, AB T1Y 7H9

Ph. 403-235-8400

Fax 403-248-3550

GERMANY

AMETEK GmbH

Rudolf-Diesel-Strasse 16

D-40670 Meerbusch

Ph. 49 21 59 91 36 0

Fax 49 21 59 91 3680

MIDDLE EAST – Dubai

AMETEK

PO Box 17067

Jebel Ali Free Zone

Dubai, UAE

Ph. 971-4-881 2052

Fax 971-4-881 2053

SINGAPORE

AMETEK Singapore Pte. Ltd.

No 43, Changi South Avenue 2, #04-01

Singapore 486164

Ph. 65-64842388

Fax 65-64816588

Contents | iii

Contents

Offices ......................................................................................................................ii

Safety Notes .......................................................................................................... vi

Environmental Information (WEEE) .............................................................. viii

General Safety Summary .....................................................................................ix

CHAPTER 1 Overview

Sensor Operations .............................................................................................. 1-1

Sensor .................................................................................................................. 1-2

Basic Elements of the Sensor ..................................................................... 1-2

The Oxygen Measuring Cell ...................................................................... 1-2

Sensor Operations - WDG-IVCM .................................................................... 1-5

Close-Coupled Extrative Flue Gas Analyzer ................................................. 1-5

Hot-Wire Type .............................................................................................. 1-5

RTD Type....................................................................................................... 1-6

Detectors .............................................................................................................. 1-7

Combustibles ................................................................................................ 1-7

Methane ........................................................................................................ 1-7

Common Operator Errors ................................................................................ 1-8

Start-Up Checklist .............................................................................................. 1-9

Technical Support ............................................................................................. 1-10

CHAPTER 2 Specications

Series 2000 Control Unit .................................................................................... 2-1

Sensor : WDG-IV ............................................................................................... 2-2

Sensor : WDG-IVC ........................................................................................... 2-3

Sensor : WDG-IVCM ........................................................................................ 2-4

Sensor : WDG-IVC - 0-500 PPM ..................................................................... 2-6

Remote Calibration Unit (RCU) ....................................................................... 2-7

CHAPTER 3 Installation

Analyzer Location .............................................................................................. 3-1

Inspect Shipping Contents ............................................................................... 3-2

Mechanical Installation ..................................................................................... 3-3

Sample Inlet Probe Installation ................................................................. 3-3

Probe Heater Installation ........................................................................... 3-6

Exhaust Tube Installation ........................................................................... 3-7

Sensor Mounting ......................................................................................... 3-7

Calibration/Aspirator Air/Z-Purge Connections................................... 3-12

Weatherproof Wall/Z-Purge Option ....................................................... 3-17

Wiring................................................................................................................. 3-19

General Wiring and Conduit Requirements ......................................... 3-20

Control Unit Mains Supply Connections .............................................. 3-21

Sensor Connections ................................................................................... 3-24

iv | Thermox Series 2000 WDG-IV / IVC / IVCM

Remote Sense Setup Wiring for Combustibles ..................................... 3-28

Current Output Connections .................................................................. 3-29

Alarm Contact Connections..................................................................... 3-30

Remote Calibration Unit Connections ................................................... 3-32

RS-485 Communications Connections ................................................... 3-34

Option Card Installation ................................................................................. 3-38

Removing Display Module or Power Supply/Keypad Module ......... 3-38

Adding an Option Card ........................................................................... 3-39

Removing an Option Card ...................................................................... 3-39

CHAPTER 4 Controller/User Interface

Areas of the Control Unit .................................................................................. 4-1

Control Unit Display ................................................................................... 4-1

Selecting Menu Options ............................................................................. 4-2

Exiting Menu Options ................................................................................ 4-2

Automatic Menu Exit Feature .................................................................... 4-3

On-Line Help ............................................................................................... 4-3

System Password ......................................................................................... 4-3

Setup Key ............................................................................................................. 4-4

Display .......................................................................................................... 4-5

Process Pressure ........................................................................................... 4-7

System Tests .................................................................................................. 4-8

System Serial # ............................................................................................ 4-8

Primary Calibration ..................................................................................... 4-9

Sensor Config ............................................................................................. 4-12

Communication ......................................................................................... 4-13

Combustibles Option ................................................................................ 4-13

Analog Range Key ............................................................................................ 4-14

Analog Output Port ................................................................................... 4-15

Set Current Range ..................................................................................... 4-15

Set Track/Hold Option .............................................................................. 4-16

Set Current Mode ...................................................................................... 4-17

Output Filtering Option ........................................................................... 4-18

Select Function ........................................................................................... 4-19

Alarm Key .......................................................................................................... 4-20

Overview of Alarm Functions ................................................................. 4-21

Alarm Set Points ......................................................................................... 4-22

Alarm Configure ........................................................................................ 4-24

Relay Configure ......................................................................................... 4-24

Select Function ........................................................................................... 4-25

Service Alarm ............................................................................................. 4-26

Watchdog Relay ......................................................................................... 4-26

Exception Log ............................................................................................. 4-27

Contents | v

Chapter 5 Calibration

Definitions ........................................................................................................... 5-2

Calibrations vs. Verifications ...................................................................... 5-2

Span and Zero Calibration Gas Definitions ............................................ 5-2

Types of Calibrations ......................................................................................... 5-3

Overview ............................................................................................................. 5-4

Aborting a Calibration ....................................................................................... 5-4

Initiate Cal and Initiate Verify .......................................................................... 5-5

Auto Calibrate/Auto Verify ......................................................................... 5-5

Remote Calibrate/Remote Verify ............................................................... 5-7

Manual Calibrate/Manual Verify ............................................................... 5-8

Calibration: Hot Wire Type Combustibles Detector .............................. 5-10

Calibration with RTD Type Combustibles Detector .............................. 5-12

Cal/Verify Data .................................................................................................. 5-14

Cal Gas Value .................................................................................................... 5-16

Inject Cal Gas .................................................................................................... 5-18

Set Cal Timers ................................................................................................... 5-20

Set Auto Timers .......................................................................................... 5-21

Set Time and Date ..................................................................................... 5-22

Auto Cal On/Off ......................................................................................... 5-22

Cal Gas Duration ....................................................................................... 5-23

Recovery Duration .................................................................................... 5-24

Set K-Factors ...................................................................................................... 5-25

Sensitivity .......................................................................................................... 5-25

Chapter 6 Maintenance and Troubleshooting

System Messages ................................................................................................ 6-2

Auto Cal Pending ......................................................................................... 6-2

Auto Verify Pending .................................................................................... 6-2

Calibration Aborted ..................................................................................... 6-2

Calibration Required ................................................................................... 6-2

Cal Verify Aborted ....................................................................................... 6-2

Power Down Detected ................................................................................ 6-2

Primary Calibration ..................................................................................... 6-2

System Calibrating ...................................................................................... 6-2

System Verifying Cal ................................................................................... 6-2

Error Messages ................................................................................................... 6-3

Cell is Over Temp ........................................................................................ 6-3

Combustibles Cal Error .............................................................................. 6-3

Excessive Cal Error ...................................................................................... 6-3

Memory is Corrupted ................................................................................. 6-3

Methane Cal Error ....................................................................................... 6-3

Span Gas Range Error ................................................................................. 6-4

Temp Rise Failure......................................................................................... 6-4

T/C (Thermocouple) Circuit Failure ......................................................... 6-4

vi |

Thermocouple Failure ................................................................................ 6-4

Zero Gas Range Error

................................................................................. 6-4

Diagnostics Checks

............................................................................................ 6-5

Wiring Checks

.............................................................................................. 6-6

Interconnecting Wiring P

roblem .............................................................. 6-6

Thermocouple Checks

................................................................................ 6-6

Shorted/Failed Ther

mocouple

................................................................... 6-6

Reversed Thermocouple W

ires

................................................................. 6-6

Thermocouple Compensation

.................................................................. 6-6

Circuit Check

................................................................................................ 6-6

Calibration/Aspirator Setup Checks

......................................................... 6-8

AC P

ower Checks

........................................................................................ 6-9

Fur

nace Checks

............................................................................................ 6-9

Process P

ressure Checks ........................................................................... 6-10

Cell Checks

................................................................................................. 6-10

General Troubleshooting

................................................................................ 6-11

Leak Check

................................................................................................. 6-11

Plugged Plumbing Check

........................................................................ 6-12

Aspirator Air Not Pulling Sample from P

rocess

................................... 6-12

Series 2000 LEDs

............................................................................................... 6-13

Auto Calibration Card LEDs

.................................................................... 6-13

Combustibles Card LEDs

......................................................................... 6-13

Combustibles and Methane Card LEDs

................................................ 6-14

Sensor Board (80471SE) LEDs

................................................................. 6-14

Chapter 7 Service and Parts

Cell Replacement/Cleaning .............................................................................. 7-4

Thermocouple Replacement

............................................................................ 7-6

Fur

nace Replacement

........................................................................................ 7-8

Combustibles Detector Replacement

............................................................ 7-10

Hot-W

ire Combustibles Detector Replacement .................................... 7-10

Box Heater Diagram

.................................................................................. 7-13

Replacement Parts List .................................................................................... 7-14

Appendix A Serial Communications

Communication Protocols ..........................................................................A-1

General Serial Communication Commands

...........................................A-3

Development Serial Communication Commands

.................................A-4

Responses

.....................................................................................................A-6

Variable Table

......................................................................................................A-7

Sample Program

...............................................................................................A-24

Starting/Monitoring a Calibration: An Example

.........................................A-25

| vii

Appendix B Menu Option Charts

Appendix C Current Outputs: Other Applications

Powering Current Outputs from an External Power Supply .................... C-1

Modulation of External Power Loop Using Current Outputs ................... C-3

Appendix D Drawings and Custom Instructions

Appendix E Series 2000 Controller Setup Parameters

viii | Thermox Series 2000 WDG-IV / IVC / IVCM

Safety Notes

WARNINGS, CAUTIONS, and NOTES contained in this manual emphasize

critical instructions as follows:

An operating procedure which, if not strictly observed, may result in

personal injury or environmental contamination.

An operating procedure which, if not strictly observed, may result in dam-

age to the equipment.

Important information that should not be overlooked.

Electrical Safety

Up to 5 kV may be present in the analyzer housings. Always shut down power

source(s) before performing maintenance or troubleshooting. Only a qualified

electrician should make electrical connections and ground checks.

Any use of the equipment in a manner not specified by the manufacturer may

impair the safety protection originally provided by the equipment.

Grounding

Instrument grounding is mandatory. Performance specifications and safety

protection are void if instrument is operated from an improperly grounded

power source.

Verify ground continuity of all equipment before applying power.

NOTE



Contents | ix

Important Notice to Users

No operator serviceable components inside any components of the WDG sys-

tem. Do not remove the cover from any WDG component. Refer servicing to

qualified personnel.

The following applies to the Series 2000 Control unit and the WDG-IV Division

2 Models:

Power, input, and output (I/O) wiring must be in accordance with Class I, Divi-

sion 2 wiring methods [Article 501-4(b) of the National Electric Code, NFPA 70]

and in accordance with the authority having jurisdiction.

WARNING - EXPLOSION HAZARD - SUBSTITUTION OF COM-

PONENTS MAY IMPAIR SUITABILITY FOR CLASS I, DIVISION 2.

WARNING - EXPLOSION HAZARD - WHEN IN HAZARDOUS LO-

CATIONS, TURN OFF POWER BEFORE REPLACING OR WIRING

MODULES.

WARNING - EXPLOSION HAZARD - DO NOT DISCONNECT

EQUIPMENT UNLESS POWER HAS BEEN SWITCHED OFF OR

THE AREA IS KNOWN TO BE NONHAZARDOUS.

THIS EQUIPMENT IS SUITABLE FOR USE IN CLASS I, DIVISION

2, GROUPS A, B, C, AND D OR NONHAZARDOUS LOCATIONS

ONLY.

The maximum ambient temperature for the Series 2000 control unit is 50 °C

(122 °F)

The Series 2000 Control Unit with WDG-IV sensor is a complex piece of equip-

ment that should only be serviced by a qualified service technician with expertise

in instrument technology and electrical systems. AMETEK recommends that

all equipment requiring service be sent back to the factory. You should only

attempt to repair or service this equipment after receiving training from an

AMETEK/P&AI Division training representative. If you decide to service this

equipment be aware that high voltages, high temperatures, and other potentially

hazardous conditions may arise.

x | Thermox Series 2000 WDG-IV / IVC / IVCM

Environmental Information (WEEE)

This AMETEK product contains materials that can be reclaimed and recycled. In some cases

the product may contain materials known to be hazardous to the environment or human

health. In order to prevent the release of harmful substances into the environment and to

conserve our natural resources, AMETEK recommends that you arrange to recycle this prod-

uct when it reached its “end of life”.

Waste Electrical and Electronic Equipment (WEEE) should never be disposed of in a munici-

pal waste system (residential trash). The Wheelie Bin marking on this product is a reminder

to dispose of the product properly after it has completed its useful life and been removed

from service. Metals, plastics, and other components are recyclable and you can do your

part by doing one of the following steps:

•

When the equipment is ready to be disposed of, take it to your local or

regional waste collection administration for recycling.

•

In some cases, your “end of life” product may be traded in for credit to-

wards the pur-chase of new AMETEK instruments. Contact your dealer to

see if this program is avail-able in your area.

•

If you need further assistance in recycling your AMETEK product, contact

our ofce listed in the front of the instruction manual.

Contents | xi

General Safety Summary

Review the following safety precautions to avoid injury and prevent damage

to this product or any products connected to it.

Use Proper Wiring

To avoid fire hazards, use only the wiring specified in the Installation Chapter

of this user’s manual.

Avoid Electrical Overload

To avoid electrical shock or fire hazard, do not apply a voltage to a terminal that

is outside the range specified for that terminal.

Ground the Product

Follow the grounding instructions provided in the Installation Chapter of this

user’s manual. Before making connections to the input or output terminals of

this product, ensure that the product is properly grounded.

Do Not Operate without Covers

To avoid electric shock or fire hazard, do not operate this product with covers

or panels removed.

Use Proper Fuse

To avoid fire hazard, use only the fuse type and rating specified for this prod-

uct.

Do Not Operate in Explosive Atmosphere

To avoid injury or fire hazard, do not operate this product in an explosive at-

mosphere unless you have purchased options that are specifically designed for

these environments.

Product Damage Precautions

Use Proper Power Source

Do not operate this product from a power source that applies more than the

voltage specified.

Do Not Operate with Suspected Failures

If you suspect there is damage to this product, have it inspected by qualified

service personnel.

xii | Thermox Series 2000 WDG-IV / IVC / IVCM

Declaration of Conformity

Manufacturer’s Name: AMETEK/Thermox

®

Manufacturer’s Address: Process & Analytical Instruments Division

150 Freeport Road

Pittsburgh, PA 15238

declares that the products:

Product Names: Thermox WDG series of Flue Gas Analyzers using Series 2000 Controller:

WDG-IV WDG-IVC WDG-IVCM

WDG-HPII WDG-HPIIC

O2 Only RCU

O2 & Comb RCU

O2, Combustibles & Methane RCU

Conform to the following standards:

EMC compliance:

EMC Directive 2004/108/EC

Immunity:

EN 50082-2:1995 Generic - Heavy Industrial Equipment

EN 50082-1:1997 Generic - Residential, Commercial, Light Industrial Equipment

EN 61000-6-2:1999 Generic - Heavy Industrial Equipment

EN 61326:1997 Measuring Equipment (Heavy Industrial)

Emissions:

EN 55011:1998 Class A, ISM Equipment

Safety Compliance:

UL 3101-1 UL Listed Inspection and Measuring Electrical Equipment

CAN/CSA 22.2 No. 1010.1-92 cUL Listed Inspection and Measuring Electrical Equipment

Low Voltage Directive 73/23/EEC:

EN61010-1:1993,

Amendment A2: 1995 Electrical Equipment for Measurement, Controls,

and Laboratory Use

Series 2000 Controller also has the following safety compliance:

UL 1604 UL Listed Process Control Equipment for Use in Hazardous Location

WDG Series analyzers with the suffix Div. 2, O2 Only RCU, O2 & Comb RCU, and O2,

Combustibles & Methane RCU also conform to the following safety standard:

UL 1604 UL Listed Process Control Equipment for Use in Hazardous Locations

Manufacturer’s Address in Europe:

AMETEK Precision Instruments Europe GmbH

Rudolf-Diesel-Strasse 16

D-40670 Meerbusch, Germany

Mark Coppler

Compliance Engineer

April 2002

Contents | xiii

WARRANTY AND CLAIMS

We warrant that any equipment of our own manufacture or manufactured for us pursuant

to our specifications which shall not be, at the time of shipment thereof by or for us, free

from defects in material or workmanship under normal use and service will be repaired or

replaced (at our option) by us free of charge, provided that written notice of such defect

is received by us within twelve (12) months from date of shipment of portable analyzers

or within eighteen (18) months from date of shipment or twelve (12) months from date of

installation of permanent equipment, whichever period is shorter. All equipment requiring

repair or replacement under the warranty shall be returned to us at our factory, or at such

other location as we may designate, transportation prepaid. We shall examine such returned

equipment, and if it is found to be defective as a result of defective materials or workman-

ship, it shall be repaired or replaced as aforesaid. Our obligation does not include the cost of

furnishing any labor in connection with the installation of such repaired or replaced equip-

ment or parts thereof, nor does it include the responsibility or cost of transportation. In ad-

dition, instead of repairing or replacing the equipment returned to us as aforesaid, we may,

at our option, take back the defective equipment, and refund in full settlement the purchase

price thereof paid by Buyer.

The warranty shall not apply to any equipment (or part thereof) which has been tampered

with or altered after leaving our control or which has been replaced by anyone except us,

or which has been subject to misuse, neglect, abuse or improper use. Misuse or abuse of the

equipment, or any part thereof, shall be construed to include, but shall not be limited to,

damage by negligence, accident, fire or force of the elements. Improper use or misapplica-

tions shall be construed to include improper or inadequate protection against shock, vibra-

tion, high or low temperature, overpressure, excess voltage and the like, or operating the

equipment with or in a corrosive, explosive or combustible medium, unless the equipment

is specifically designed for such service, or exposure to any other service or environment of

greater severity than that for which the equipment was designed.

The warranty does not apply to used or secondhand equipment nor extend to anyone other

than the original purchaser from us.

THIS WARRANTY IS GIVEN AND ACCEPTED IN LIEU OF ALL OTHER WARRANTIES,

WHETHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION AND WAR-

RANTIES OF FITNESS OR OF MERCHANTABILITY OTHER THAN AS EXPRESSLY SET

FORTH HEREIN, AND OF ALL OTHER OBLIGATIONS OR LIABILITIES ON OUR PART.

IN NO EVENT SHALL WE BE LIABLE UNDER THIS WARRANTY OR ANY OTHER

PROVISION OF THIS AGREEMENT FOR ANY ANTICIPATED OR LOST PROFITS, INCI-

DENTAL DAMAGES, CONSEQUENTIAL DAMAGES, TIME CHANGES OR ANY OTHER

LOSSES INCURRED BY THE ORIGINAL PURCHASER OR ANY THIRD PARTY IN CON-

NECTION WITH THE PURCHASE, INSTALLATION, REPAIR OR OPERATION OF EQUIP-

MENT, OR ANY PART THEREOF COVERED BY THIS WARRANTY OR OTHERWISE. WE

MAKE NO WARRANTY, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

ANY WARRANTIES OF FITNESS OR OF MERCHANTABILITY, AS TO ANY OTHER MAN-

UFACTURER’S EQUIPMENT, WHETHER SOLD SEPARATELY OR IN CONJUNCTION

WITH EQUIPMENT OF OUR MANUFACTURE. WE DO NOT AUTHORIZE ANY REPRE-

SENTATIVE OR OTHER PERSON TO ASSUME FOR US ANY LIABILITY IN CONNEC-

TION WITH EQUIPMENT, OR ANY PART THEREOF, COVERED BY THIS WARRANTY.

xiv | Thermox Series 2000 WDG-IV / IVC / IVCM

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Overview | 1-1

OVERVIEW

Sensor Operations

Designed for fast response in a wide range of flue gas applications, the

sensor mounts directly on the combustion process to provide continuous

measurement of oxygen, or oxygen and combustibles, or oxygen, combus-

tibles and methane.

A sample is drawn from the process stream by means of an air-operated

aspirator and is immediately returned to the process. A portion of this gas

rises past the oxygen measuring cell and combustibles detector and re-

turns to the primary loop. All sample wetted parts are heated to maintain

the sample above the dewpoint of the gas.

Follow these cautions when working on the sensor:

Do not turn on the aspirator until the analyzer has been turned on

and is hot - preferably 24 hours. Also, if you turn off the analyzer or

the process is shut down, turn off the aspirator air to avoid plugging

problems!

Remove AC power from the sensor and control unit and allow the

sensor to cool for at least one hour before performing any maintenance

or troubleshooting activities.

The outside of the sensor cover and all sensor assembly components

are hot during normal operation (up to 500° F, 260° C inside the

cover). Allow sensor components to cool for at least an hour before

working inside the sensor. Use caution and wear appropriate gloves

when handling components or when touching the sensor cover!

1-2 | Thermox Series 2000 WDG-IV / IVC / IVCM

Sensor

Basic Elements of the Sensor

The WDG-IV series analyzer consists of the following basic systems:

 The Plumbing

 All inlet and outlet tubing (cell housing), the oxygen cell, the oxygen

cell fitting, and the combustibles flow block and detector (for combus-

tibles). Also includes the calibration gas inlet and aspirator assembly,

with the aspirator used to pull the sample into the sensor.

 The Measuring System

 The oxygen cell, combustibles detector (RTD or hot-wire type), meth-

ane detector, interconnecting wiring, and control unit.

 The Temperature System

The electrical cell heater (furnace), sensor case heaters, the type “K”

thermocouple (maintains cell operating temperature), and the sensor

board containing cold junction compensation. The sensing cell oper-

ates at a constant temperature. The circuit board in the sensor terminal

box switches power to the furnace from the AC mains connected to

the sensor. This board also provides cold junction compensation to the

thermocouple circuit.

The Oxygen Measuring Cell

The sensing element itself is a closed-end tube or disk made from ceramic

zirconium oxide stabilized with an oxide of yttrium or calcium. Porous

platinum coatings on the inside and outside serve as a catalyst and as

electrodes. At high temperatures (generally above 1200°F/650°C), oxygen

molecules coming in contact with the platinum electrodes near the sensor

become ionic. As long as the oxygen partial pressures on either side of the

cell are equal, the movement is random and no net flow of ions occurs.

If, however, gases having different oxygen partial pressures are on either

side of the cell, a potentiometric voltage is produced (See Figure 1-1).

The magnitude of this voltage is a function of the ratio of the two oxygen

partial pressures. If the oxygen partial pressure of one gas is known, the

voltage produced by the cell indicates the oxygen content of the other gas.

A reference gas, usually air (20.9% O

2

), is used for one of the gases.

Overview | 1-3

Figure 1-1. Zirconium oxide cell principle of operation.

Since the voltage of the cell is temperature dependent, the cell is main-

tained at a constant temperature. Some newer high temperature insitu

models use the heat from the process to heat the sensor, and the process

temperature is continuously measured and used in the software calcula-

tion. The oxygen content is then determined from the Nernst equation:

E = In

RT

4F

O

1

O

2

where R and F are constants, T is absolute temperature, and O

1

and O

2

are

the oxygen partial pressures on either side of the cell.

For measuring oxygen in non-combustibles gases, the calibration of an

analyzer is obtained from the formula:

AT = 48.0 at 695°C

E = A

*

T

*

Log

20.9%

O

2

Unk%

Where A is a constant, T is the cell temperature on an absolute scale (°C +

273) and O

2

Unk% is the unknown oxygen concentration of the gas to be

analyzed, and which is calculated by the analyzer.

1-4 | Thermox Series 2000 WDG-IV / IVC / IVCM

The cell produces zero voltage when the same amount of oxygen is on

both sides, and the voltage increases as the oxygen concentration of the

sample decreases. The voltage created by the difference in the sample gas

and the reference air is carried by a cable to the microprocessor control

unit, where it is linearized to an output signal.

Because of the high operating temperature of the cell, combustible

gases that are present may burn. When this occurs, the cell will gener-

ate high millivolts and cause the display to indicate less oxygen than

is actually in the gas (net oxygen content).

Hydrocarbons

When hydrocarbons are present in the gas sample, a combustion process

occurs when this gas sample is exposed to the high temperature of the

zirconia cell. An indication that hydrocarbons may be present in the gas

sample is that the oxygen reading will be lower than expected. For exam-

ple, if a calibration gas cylinder has an oxygen value of 20 PPM and 5 PPM

of hydrogen (balance nitrogen), the oxygen analyzer will read 17.5 PPM

oxygen. The reduction of oxygen is due to the combustion process where

5 PPM of hydrogen will combine with 2.5 PPM of oxygen to form water.

Thus, the oxygen analyzer will read 17.5 PPM rather than the actual 20

PPM oxygen.

The amount of oxygen reduction is dependent on the type of hydrocar-

bons present in the sample gas.

NOTE



NOTE



Overview | 1-5

Sensor Operations - WDG-IVCM

Close-Coupled Extrative Flue Gas Analyzer

The WDG-IVCM analyzer is ideal for natural gas-fired power boilers or

for those using gas during start-up and shutdown. With this analyzer, you

can monitor oxygen and combustibles for maximum fuel efficiency. In

addition, the methane detector can be used for purge and lightoff cycles

during start-up and shutdown.

Hot-Wire Type

WDG-IVCM analyzers with hot-wire type combustibles detector (see

Figure 1-2) are used for processes that use natural gas for start-up and oil,

fuel gas or coal for primary fuel. Process gas is drawn into the analyzer’s

primary sample loop by an aspirator and returns to process. Gas enters

the split flow block that is separted by a baffle and contacts the hot-wire

catalytic combustibles and methane detector. It then passes the zirconium

oxide cell, where the oxygen concentration is measured, before returning

to the main sample loop and then back to the process.

CELL HOUSING

ZIRCONIUM OXIDE

OXYGEN CELL

CONVECTION LOOP

RETURN

METHANE DETECTOR

SAMPLE

ASPIRATOR AIR

ASPIRATOR BLOCK

RETURN TO

PROCESS

PPM OR PERCENT

COMBUSTIBLES DETECTOR

Figure 1-2. WDG-IVCM with hot-wire type combustibles detector convection loop.

1-6 | Thermox Series 2000 WDG-IV / IVC / IVCM

RTD Type

WDG-IVCM analyzer with RTD-wire type combustibles detector (see Fig-

ure 1-3) is used for natureal gas fired boilers (natural gas for start-up and

primary fuel). Process gas is drawn into the analyzer’s primary sample

loop by an aspirator and return to process. Gas enters the RTD-type com-

bustibles detector flow block and contacts RTD-type combustibles detec-

tor. The gas then travels into the hot-wire methane detector flow block

where it contacts the methane sensor. It then passes the zirconium oxide

cell, where the oxygen concentration is measured, before returning to the

main sample loop and then back to the process.

ZIRCONIUM OXIDE

OXYGEN CELL

HOT-WIRE TYPE

METHANE DETECTOR

RTD-TYPE

COMBUSTIBLES DETECTOR

ASPIRATOR BLOCK

CELL

HOUSING

CONVECTION

LOOP

RETURN

SAMPLE

ASPIRATOR AIR

RETURN

TO PROCESS

Figure 1-3. WDG-IVCM with RTD-wire type combustibles detector convection loop.

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Ametek Thermox Series 2000 WDG-IVC User manual

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