Emerson NGA 2000 TO2 User manual

Instruction Manual

760008-A

September 2001

http://www.processanalytic.com

Model NGA 2000 TO2

Trace Oxygen Analyzer

Emerson Process Management

Rosemount Analytical Inc.

Process Analytic Division

1201 N. Main St.

Orrville, OH 44667-0901

T (330) 682-9010

F (330) 684-4434

e-mail: [email protected]

http://www.processanalytic.com

ESSENTIAL INSTRUCTIONS

READ THIS PAGE BEFORE PROCEEDING!

Rosemount Analytical designs, manufactures and tests its products to meet many national and

international standards. Because these instruments are sophisticated technical products, you

MUST properly install, use, and maintain them to ensure they continue to operate within their

normal specifications. The following instructions MUST be adhered to and integrated into your

safety program when installing, using, and maintaining Rosemount Analytical products. Failure to

follow the proper instructions may cause any one of the following situations to occur: Loss of life;

personal injury; property damage; damage to this instrument; and warranty invalidation.

• Read all instructions prior to installing, operating, and servicing the product.

• If you do not understand any of the instructions, contact your Rosemount Analytical repre-

sentative for clarification.

• Follow all warnings, cautions, and instructions marked on and supplied with the product.

• Inform and educate your personnel in the proper installation, operation, and mainte-

nance of the product.

• Install your equipment as specified in the Installation Instructions of the appropriate In-

struction Manual and per applicable local and national codes. Connect all products to the

proper electrical and pressure sources.

• To ensure proper performance, use qualified personnel to install, operate, update, program,

and maintain the product.

• When replacement parts are required, ensure that qualified people use replacement parts

specified by Rosemount. Unauthorized parts and procedures can affect the product’s per-

formance, place the safe operation of your process at risk, and VOID YOUR WARRANTY.

Look-alike substitutions may result in fire, electrical hazards, or improper operation.

• Ensure that all equipment doors are closed and protective covers are in place, except

when maintenance is being performed by qualified persons, to prevent electrical shock

and personal injury.

The information contained in this document is subject to change without notice.

Teflon

®

is a registered trademark of E.I. duPont de Nemours and Co., Inc.

SNOOP

®

is a registered trademark of NUPRO Co.

Waferpure™ is a trademark of Millipore Corp.

Nanochem

®

is a registered trademark of Semigas Corp

Instruction Manual

760008-A

September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Contents i

Model NGA 2000 TO2

TABLE OF CONTENTS

PREFACE...........................................................................................................................................P-1

intended use statement ......................................................................................................................P-1

Definitions ...........................................................................................................................................P-1

Safety Summary .................................................................................................................................P-2

General precautions for handling and storing high pressure gas cylinders .......................................P-3

Documentation....................................................................................................................................P-4

Compliances .......................................................................................................................................P-4

Glossary..............................................................................................................................................P-5

1-0 DESCRIPTION AND SPECIFICATIONS.................................................................................1-1

1-2 Overview...................................................................................................................................1-1

1-3 Typical Applications..................................................................................................................1-1

1-4 Method of measurement ..........................................................................................................1-1

1-5 Features ...................................................................................................................................1-1

a. General .......................................................................................................................1-4

b. Sample........................................................................................................................1-4

c. Physical .......................................................................................................................1-4

d. Gas Connections ........................................................................................................1-5

2-0 INSTALLATION ....................................................................................................................2-1

2-1 Unpacking ................................................................................................................................2-1

2-2 Assembly ..................................................................................................................................2-1

a. Electrolyte Addition .....................................................................................................2-1

2-3 Location ....................................................................................................................................2-1

2-4 Gases .......................................................................................................................................2-2

a. Requirements..............................................................................................................2-2

b. Sample........................................................................................................................2-2

c. Pressure ......................................................................................................................2-2

2-5 Connections .............................................................................................................................2-2

a. Leak Test ....................................................................................................................2-3

2-6 Electrical Connections..............................................................................................................2-3

3-0 OPERATION ............................................................................................................................3-1

3-1 Overview...................................................................................................................................3-1

3-2 Displays & Operating Keys.......................................................................................................3-1

a. Menu Lines & Softkey Functionality............................................................................3-2

b. Common Function Keys...............................................................................................3-2

c. Entering & Changing Variables....................................................................................3-3

d. Starting a Function.......................................................................................................3-3

e. Measure Mode Display ................................................................................................3-4

f. Main Menu ....................................................................................................................3-4

3-3 Startup & Initialization...............................................................................................................3-6

a. Quick Start ..................................................................................................................3-7

3-4 Basic Controls, Setup and Status ............................................................................................3-8

a. Analyzer Channel Status ............................................................................................3-8

b. Single Component Display .........................................................................................3-9

c. Multi Component Display ............................................................................................3-10

d. Basic Controls and Setup ...........................................................................................3-11

Instruction Manual

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September 2001

ii Contents Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

e. Display Controls..........................................................................................................3-12

3-5 Expert Controls and Setup .......................................................................................................3-13

a. Calibration Procedure .................................................................................................3-14

b. Alarms .........................................................................................................................3-17

c. Ranges........................................................................................................................3-18

d. Linearization................................................................................................................3-19

e. Measurement Display Configuration...........................................................................3-19

f. Concentration Measurement .......................................................................................3-20

g. Flow Measurement .....................................................................................................3-22

h. Temperature Measurement ........................................................................................3-23

3-6 System & Network I/O Module Controls (Setup)......................................................................3-24

a. System SIO.................................................................................................................3-25

b. Analog Output Setup...................................................................................................3-26

c. Serial Interface Setup..................................................................................................3-29

d. Relay Outputs Setup...................................................................................................3-30

e. System DIO.................................................................................................................3-31

3-7 System Configuration and Diagnostics ....................................................................................3-32

a. Diagnostic Menus .......................................................................................................3-33

4-0 MAINTENANCE AND SERVICE .............................................................................................4-1

4-1 Overview...................................................................................................................................4-1

4-2 Sensor ......................................................................................................................................4-1

a. Refilling .......................................................................................................................4-2

b. Electrolyte Replacement.............................................................................................4-3

c. Sensor Replacement...................................................................................................4-3

4-3 Linearization .............................................................................................................................4-4

4-4 Flow Sensor Replacement .......................................................................................................4-6

4-5 Electronic Components ............................................................................................................4-6

a. Fuses ..........................................................................................................................4-6

b. Printed Circuit Boards .................................................................................................4-6

5.0 TROUBLESHOOTING .............................................................................................................5-1

5-1 Troubleshooting........................................................................................................................5-1

a. Failure to purge down to ppm levels...........................................................................5-1

b. Flow sensitivity............................................................................................................5-1

c. Erratic and very insensitive readings ..........................................................................5-1

6-0 REPLACEMENT PARTS........................................................................................................6-1

6-1 Matrix........................................................................................................................................6-1

6-2 Replacement Parts...................................................................................................................6-2

7-0 RETURN OF MATERIAL..........................................................................................................7-1

7-1 Return of Material.....................................................................................................................7-1

7-2 Customer Service.....................................................................................................................7-1

7-3 Training.....................................................................................................................................7-1

8-0 INDEX.......................................................................................................................................8-1

MATERIAL SAFETY DATA SHEET 748377

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Contents iii

Model NGA 2000 TO2

LIST OF ILLUSTRATIONS

Figure 1-1. Trace Oxygen Detector Coulometric Principle..............................................................1-2

Figure 1-2. Trace Oxygen Analyzer Module - Top View .................................................................1-3

Figure 2-1. Analyzer Module Interconnection with Instrument Platform .........................................2-4

Figure 2-2. Outline and Mounting Dimensions ................................................................................2-5

Figure 2-3. Back Panel Connections...............................................................................................2-6

Figure 2-4. Trace Oxygen Analyzer Front Panel.............................................................................2-6

Figure 3-1. Platform Front Panel .....................................................................................................3-1

Figure 3-2. The Display Screen.......................................................................................................3-2

Figure 3-3. Changing Variables.......................................................................................................3-3

Figure 3-4. Function Confirmation...................................................................................................3-3

Figure 3-5. Measure Mode Display .................................................................................................3-4

Figure 3-7. Module Manufacturing Data Displays ...........................................................................3-5

Figure 3-8. Startup Display..............................................................................................................3-6

Figure 3-9. Initiate Quick Start.........................................................................................................3-7

Figure 3-10. Analyzer Channel Status .............................................................................................3-8

Figure 3-11. Single Component Display............................................................................................3-9

Figure 3-12. Multi Component Display ..............................................................................................3-10

Figure 3-13. Basic Controls and Setup .............................................................................................3-11

Figure 3-14. Display Controls ............................................................................................................3-12

Figure 3-15. Expert Controls and Setup............................................................................................3-13

Figure 3-16. Calibration – Gas Scale Factor .....................................................................................3-15

Figure 3-17. Span Calibration............................................................................................................3-16

Figure 3-18. Alarms ...........................................................................................................................3-17

Figure 3-19. Ranges..........................................................................................................................3-18

Figure 3-20. Measurement Display Configuration.............................................................................3-19

Figure 3-21. Concentration Measurement.........................................................................................3-20

Figure 3-22. Flow Measurement........................................................................................................3-22

Figure 3-23. Temperature Measurement ..........................................................................................3-23

Figure 3-24. System & Network I/O Module Controls .......................................................................3-24

Figure 3-25. System SIO Module ......................................................................................................3-25

Figure 3-26. System Configuration and Diagnostics .........................................................................3-32

Figure 4-1. Sensor Assembly ..........................................................................................................4-2

Instruction Manual

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September 2001

iv Contents Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-1

Model NGA 2000 TO2

PREFACE

INTENDED USE STATEMENT

The purpose of this manual is to provide information concerning the components, functions, installation and

maintenance of the Model NGA 2000 TO2 and the System Accessories of the NGA 2000 System.

Some sections may describe equipment not used in your configuration. The user should become thor-

oughly familiar with the operation of this module before operating it. Read this instruction manual com-

pletely.

DEFINITIONS

The following definitions apply to DANGERS, WARNINGS, CAUTIONS and NOTES found throughout

this publication.

DANGER .

Highlights the presence of a hazard which will cause severe personal injury, death, or sub-

stantial property damage if the warning is ignored.

WARNING .

Highlights an operation or maintenance procedure, practice, condition, statement, etc. If not

strictly observed, could result in injury, death, or long-term health hazards of personnel.

CAUTION.

Highlights an operation or maintenance procedure, practice, condition, statement, etc. If not

strictly observed, could result in damage to or destruction of equipment, or loss of effective-

ness.

NOTE

Highlights an essential operating procedure,

condition or statement.

Instruction Manual

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September 2001

P-2 Preface Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

SAFETY SUMMARY

If this equipment is used in a manner not specified in these instructions, protective systems may be im-

paired.

DANGER.

ELECTRICAL SHOCK HAZARD

Operate this equipment only when covers are secured. Servicing requires access to live parts

which can cause death or serious injury. Refer servicing to qualified personnel. For safety

and proper performance, this module must be connected to a properly grounded three-wire

source of electrical power.

DANGER.

POSSIBLE EXPLOSION HAZARD

This equipment is not designed and should not be used in the analysis of flammable sam-

ples. Use of this equipment in this way could result in explosion and death.

WARNING.

HIGH PRESSURE GAS CYLINDERS

This analyzer requires use of pressurized gas. See General Precautions for Handling and

Storing High Pressure Cylinders, page P-3.

WARNING.

PARTS INTEGRITY

Tampering or unauthorized substitution of components may adversely affect safety of this

product. Use only factory documented components for repair.

CAUTION.

CAUSTIC LIQUID

Electrolyte is a caustic solution. Review the Material Safety Data Sheet in the rear of this

manual.

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-3

Model NGA 2000 TO2

GENERAL PRECAUTIONS FOR HANDLING AND STORING HIGH

PRESSURE GAS CYLINDERS

Edited from selected paragraphs of the Compressed

Gas Association's "Handbook of Compressed Gases"

published in 1981

Compressed Gas Association

1235 Jefferson Davis Highway

Arlington, Virginia 22202

Used by Permission

1. Never drop cylinders or permit them to strike each other violently.

2. Cylinders may be stored in the open, but in such cases, should be protected against extremes of

weather and, to prevent rusting, from the dampness of the ground. Cylinders should be stored in the

shade when located in areas where extreme temperatures are prevalent.

3. The valve protection cap should be left on each cylinder until it has been secured against a wall or

bench, or placed in a cylinder stand, and is ready to be used.

4. Avoid dragging, rolling, or sliding cylinders, even for a short distance; they should be moved by using a

suitable hand-truck.

5. Never tamper with safety devices in valves or cylinders.

6. Do not store full and empty cylinders together. Serious suckback can occur when an empty cylinder is

attached to a pressurized system.

7. No part of cylinder should be subjected to a temperature higher than 125

°

F (52

°

C). A flame should

never be permitted to come in contact with any part of a compressed gas cylinder.

8. Do not place cylinders where they may become part of an electric circuit. When electric arc welding,

precautions must be taken to prevent striking an arc against the cylinder.

Instruction Manual

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September 2001

P-4 Preface Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

DOCUMENTATION

The following NGA 2000 TO2 instruction materials are available. Contact Customer Service Center or

the local representative to order.

760008 Instruction Manual (this document)

COMPLIANCES

This product may carry approvals from several certifying agencies for use in non-hazardous, indoor loca-

tions. If so, the product will carry approval insignia on the product name-rating plate.

Rosemount Analytical Inc. has satisfied all obligations from the European Legislation to harmonize the

product requirements in Europe.

These products comply with the standard level of NAMUR EMC. Recommendation (May 1993).

This product satisfies all obligations of all relevant standards of the EMC framework in Australia and New

Zealand.

NAMUR

®

NRTL/C

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-5

Model NGA 2000 TO2

GLOSSARY OF TERMS

Analyzer Module

The module that contains all sensor/detector components for development of a Primary Variable signal; in-

cludes all signal conditioning and temperature control circuitry.

Backplane

The interconnect circuit board which the Controller Board, Power Supply, Analyzer Module power and net-

work cables, I/O Modules and Expansion Modules plug into.

Control Module

The Operator Interface plus the Controller Board.

Controller Board

The computer board that serves as the Network Manager and operates the Display and Keypad.

Distribution Assembly

The Backplane and the card cages that hold I/O and Expansion Modules.

Expansion Module

A circuit board that plugs into the Backplane from the front of the Platform and performs special features

not related to I/O functions.

I/O Module

A circuit board that plugs into the Backplane from the rear of the Platform. Has a connector terminal for

communication with external data acquisition devices and provides an input/output function.

Operator Interface

The Display and Keyboard.

Platform

Any workable collection of the following: Controller Board, Power Supply, Distribution Assembly, Enclosure

and Operator Interface.

Power Supply

Any of a variety of components that provides conditioned power to other NGA 2000 components, from the

Power Supply Board that plugs into the front of the Backplane in a stand-alone instrument to several larger

ones that can power larger collections of modules and components.

Primary Variable

The measured species concentration value from an Analyzer Module.

Secondary Variable

Data placed on the network by a module regarding current status, e.g., sample flow, source voltage and

other diagnostic information.

Instruction Manual

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September 2001

P-6 Preface Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

Softkeys

The five function keys located below the front panel display; they assume the function displayed directly

above each on the display, a function dictated by software.

System

Any collection of Analyzer Module(s), Platform(s), I/O Module(s) and Expansion Module(s).

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-1

Model NGA 2000 TO2

SECTION 1

DESCRIPTION AND SPECIFICATIONS

1-1 OVERVIEW

This manual describes the Trace Oxygen

(TO2) Analyzer Module of Rosemount Ana-

lytical's NGA 2000 Series of gas analysis

components.

The TO2 Analyzer Module is designed to con-

tinuously determine the concentration of trace

oxygen in a flowing gaseous mixture. The

concentration is expressed in parts-per-

million.

The TO2 Analyzer Module is configured as a

shelf-mount module, designed to be installed

external from the platform on an associated

shelf capable of holding two modules side-by-

side, with gas connections made from the

rear. All electronics relative to sample detec-

tion and conditioning are included in this

module.

1-2 TYPICAL APPLICATIONS

The TO2 Analyzer Module has specific appli-

cations in the following areas:

• Trace oxygen in product nitrogen

and argon streams from air

separation plants

• Trace oxygen in inerting atmos-

pheres for heat treat furnaces

• Trace oxygen in glove-box appli-

cations

1-3 METHOD OF MEASUREMENT

Coulometric Principle

The TO2 Analyzer Module uses the cou-

lometric principle of oxygen detection. This

technology is based on the fact that oxygen in

the sample is reduced by an electrochemical

reaction. This reduction occurs at the cathode

and results in the generation of hydroxyl ions.

These hydroxyl ions migrate to the anode

where they are oxidized to reform oxygen.

The oxidation reaction generates four elec-

trons which in turn migrate to the anode to

participate in the reduction reaction:

(Cathode Reaction)

O

2

+ 2 H

2

O + 4 e

-

→ 4 OH

-

(Anode Reaction)

4 OH

-

→ O

2

+ 2 H

2

O + 4 e

-

A polarizing voltage of approximately 1.3 VDC

is applied between the anode and cathode to

drive the oxidation and reduction reactions.

The resulting current flow produced by the

flow of electrons is directly proportional to the

oxygen content in the sample gas.

1-4 FEATURES

Among the features included in the TO2 Ana-

lyzer Module are:

• Quick start feature

• Electrolyte level alarm

• High oxygen protection circuit

with alarm

• Sample flow indication.

Instruction Manual

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September 2001

1-2 Description and Specifications Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

Figure 1-1. Trace Oxygen Detector Coulometric Principle

ELECTRONICS

SECONDARY ANODE (+)

BI-STRATA™ DIFFUSION BAR-

RIER

SAMPLE IN

SAMPLE OUT

O

2

SENSING CATHODE (-)

SECONDARY CATHODE (-)

O

2

SENSING ANODE (-)

O

2

O

2

e

-

e

-

KOH

OH

-

S

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-3

Model NGA 2000 TO2

Figure 1-2. Trace Oxygen Analyzer Module - Top View

Sensor Assembly

Sensor

Sample Flow

Sensor

Network/Power

Module

Computer

Board

Power Board

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September 2001

1-4 Description and Specifications Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

1-5 SPECIFICATIONS

1

a. General

Measurement Species................................... Trace Oxygen

Ranges .......................................................... 0 to 100 ppm (output scalable down to 0-2 ppm fullscale)

Accuracy........................................................ ±3% of reading or ±0.02% of range (except for ranges ≤

100 ppm: ±3% of reading or ±0.05% of range)

Sensitivity ...................................................... <10 ppb Oxygen

Noise ............................................................. 1% of fullscale, peak to peak

Linearity ......................................................... ±1% of fullscale

Response Time ............................................. Typically 90% in less than 20 seconds

Zero Drift........................................................ ≤±1% of fullscale/24 hours at constant temperature

Span Drift....................................................... ≤±1% of fullscale/24 hours at constant temperature

Effect of Temperature.................................... 0.32% of reading per °F from 70°F (0.58% of reading per

°C from 21°C)

Effect of Flow................................................. ≤2% of reading for a flow change of ±250 cc/min (0.5

SCFH)

Operating Temperature ................................. 32°F to 113°F (0°C to 45°C)

Power Requirements..................................... +24 VDC ±5%, 10 W max.

Ripple and Noise ........................................... <100 mV peak to peak

Line and Load Regulations............................ <±1%

b. Sample

Sample .......................................................... Non-flammable (below 100% of the LEL)

Flow Rate ...................................................... 0.5 to 1.5 L/min.

Supply Pressure ............................................ 1027 to 1082 hPa - absolute (0.2 to 1.0 psig)

Temperature.................................................. 32°F to 113°F (0°C to 45°C)

Particulates.................................................... filtered to <0.1 mg/L; non-condensing at ambient tem-

perature

Sample Humidity ........................................... non-condensing at ambient temperatures

c. Physical

Materials in contact with sample ................... Stainless steel, Teflon, Delrin, neoprene

Dimensions.................................................... See Figure 2-2, Outline and Mounting Dimensions

Weight ........................................................... 6.8 kg (15 lbs.)

Mounting........................................................ Horizontal, external to Platform or custom installed in a

panel

Case Classification........................................ General Purpose for installation in weather protected

area

Max. Separation from Platform...................... 1600 m (1 mile)

1

See the Platform manual for specifications regarding Platform related components.

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-5

Model NGA 2000 TO2

d. Gas Connections

Sample In ...................................................... 1/4 inch O.D. tube fitting

Sample Out.................................................... 1/4 inch O.D. tube fitting

Instruction Manual

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September 2001

1-6 Description and Specifications Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

Instruction Manual

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September 2001

Rosemount Analytical Inc. A Division of Emerson Process Management Installation 2-1

Model NGA 2000 TO2

SECTION 2

INSTALLATION

WARNING.

Before starting to install this equip-

ment, read the Safety Summary in

the Preface section of this manual.

Failure to follow the safety instruc-

tions could result in serious injury or

death.

2-1 UNPACKING

If the Trace Oxygen (TO2) Analyzer Module is

received as a separate unit, carefully examine

the shipping carton and contents for signs of

damage. Immediately notify the shipping car-

rier if the carton or contents is damaged. Re-

tain the carton and packing material until all

components associated with the TO2 Ana-

lyzer Module are operational.

2-2 ELECTROLYTE

Before installation of the TO2 Analyzer Mod-

ule, electrolyte must be added to the Sensor.

Follow the procedure described in Section 2-

2a.

After addition of electrolyte, locate the ana-

lyzer module on an appropriate mounting

surface and connect the network cable to ei-

ther the NETWORK 1 or NETWORK 2 con-

nection on the Analyzer Module, and the

NETWORK connection on the Platform net-

work I/O port. (See Figure 2-1 and Figure

2-4.)

a. Electrolyte Addition

Before adding electrolyte to the Sensor, it

is recommended to check the Sensor for

possible leakage caused by damage in

shipment. To check the Sensor for leak-

age, remove the top cover of the Analyzer

Module and locate and remove the 5

mounting screws which hold the Sensor

Assembly (Sensor, flow meter, plumbing,

inlet/outlet fittings) to the module (see

Figure 4-1). Be careful not to lose these

screws as they have metric threads.

Carefully lift out the Sensor assembly and

remove from the analyzer module. Place

on a flat surface and remove the black

Sensor cover by unscrewing counter-

clockwise.

Add distilled or deionized water to the

Sensor to the maximum level indication

on the Sensor reservoir. Let Sensor

stand for approximately 15 minutes and

check for leaks around the base of the

reservoir, and at the seams and corners.

If a leak is found, contact the factory be-

fore proceeding. Drain the Sensor.

Fill the Sensor with one bottle of electro-

lyte supplied with the analyzer module.

Use the entire contents of the bottle.

NOTE

Do not add water. The volume and

concentration of the bottled electrolyte

is pre-measured.

Reinstall the black Sensor cover and

carefully reinstall the Sensor Assembly

inside the Analyzer Module. Do not tilt

the Sensor Assembly excessively as

electrolyte may leak out.

2-3 LOCATION

(See Figure 2-2) The TO2 Analyzer Module

comes standard with mounting ears for easy

installation on flat, horizontal surfaces. Install

the TO2 Analyzer Module in a clean, weather-

proofed, vibration-free location free from ex-

treme temperature variations and moisture.

For best results, install the instrument near

the sample stream to minimize sample trans-

port time.

Operating ambient temperature is 0 °C to 45

°C (32 °F to 81 °F). Temperature change

should not exceed 10 °C (18 °F) per hour.

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2-2 Installation Rosemount Analytical Inc. A Division of Emerson Process Management

Model NGA 2000 TO2

The same temperature restrictions apply to

the location of the zero and span gas cylin-

ders.

2-4 GASES

a. Requirements

The TO2 Analyzer Module requires only a

standard of accurately known composition

for use as a span gas. The span gas

should be supplied from a cylinder

equipped with a clean, metallic dia-

phragm, two-stage regulator. A shutoff

valve is recommended.

Calibration Gases

The TO2 module does not require routine

zero calibration. The zero is factory set

and does not experience routine drift.

Over long periods of time, the zero may

experience minor drift. For low ppm

range analyzers, you may wish to check

the zero at one year intervals. Oxygen-

free nitrogen is recommended for use as

zero gas. This gas is certified to <0.5

ppm oxygen and can be improved by

passing the zero gas through an oxygen

scrubber such as Millipore™ Waferpure

or Semigas Nanochem® resin purifiers. A

mixture of trace oxygen in a background

of nitrogen is recommended as span gas.

For maximum accuracy, the concentration

of trace oxygen in the span gas should be

as high as possible for the range of

measurement.

b. Sample

The sample must be clean and dry before

entering the Analyzer Module. Sample

should be filtered for particulates down to

two microns, and should have a dew point

at least 5 °C (13 °F) below the coldest ex-

pected ambient temperature.

c. Pressure

Constant between 13.8 and 69 hPa -

gauge (0.2 and 1.0 psig) sample inlet

pressure is recommended. If a needle

valve is used upstream of the Analyzer

Module to control flow, the inlet pressure

to the needle valve should not exceed

345 hPa (5 psig). A constant sample flow

rate between 1.0 to 3.0 SCFH (0.5 to 1.5

l/min) is recommended for best results.

The Analyzer Module must vent to at-

mosphere to avoid back pressure influ-

ences on the oxygen reading.

2-5 GAS CONNECTIONS

(See Figure 2-3. ) Connect inlet and outlet

lines for sample to appropriately labeled fit-

tings on the rear panel. SAMPLE IN and

SAMPLE OUT are 1/4-inch ferrule-type com-

pression fittings. Zero and span gases should

be introduced at the SAMPLE IN fitting at

normal sample inlet flow rate.

Metallic tubing is recommended for the sam-

ple line. The use of plastic, Teflon, or other

non-metallic tubing can result in ambient oxy-

gen permeation through the tubing causing

higher than expected reading. Exhaust tub-

ing should be 1/4 inch (6.3 mm) or larger, and

can be metallic or non-metallic.

CAUTION.

GAS OVERPRESSURE

At no time should sample, zero or span

gas inlet pressure exceed 69 hPa - gauge

(1.0 psig). Damage to the Sensor may oc-

cur if this pressure level is exceeded.

CAUTION.

SAMPLE FLOW

Do not test the sample pressure by block-

ing the exhaust. When the pressure is re-

leased the sudden surge of flow will spin

the internal flowmeter off its bearings and

destroy it.

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Emerson NGA 2000 TO2 User manual

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Emerson NGA 2000 TO2 User manual

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