Teledyne 3020T User Manual

Trace Oxygen Analyzer

OPERATING INSTRUCTIONS FOR

Model 3020T

Trace Oxygen Analyzer

DANGER

HIGHLY TOXIC AND OR FLAMMABLE LIQUIDS OR GASES MAY BE PRESENT IN THIS
MONITORING SYSTEM.

PERSONAL PROTECTIVE EQUIPMENT MAY BE REQUIRED WHEN SERVICING THIS SYSTEM.
HAZARDOUS VOLTAGES EXIST ON CERTAIN COMPONENTS INTERNALLY WHICH MAY PER-

SIST FOR A TIME EVEN AFTER THE POWER IS TURNED OFF AND DISCONNECTED.
ONLY AUTHORIZED PERSONNEL SHOULD CONDUCT MAINTENANCE AND/OR SERVICING.

BEFORE CONDUCTING ANY MAINTENANCE OR SERVICING CONSULT WITH AUTHORIZED
SUPERVISOR/MANAGER.

Teledyne Analytical Instruments

P/N M65908

11/22/99

ECO # 99-0459

i

Model 3020T

Copyright © 1999 Teledyne Analytical Instruments

All Rights Reserved. No part of this manual may be reproduced, transmitted, tran­scribed, stored in a retrieval system, or translated into any other language or computer
language in whole or in part, in any form or by any means, whether it be electronic,
mechanical, magnetic, optical, manual, or otherwise, without the prior written consent of
Teledyne Analytical Instruments, 16830 Chestnut Street, City of Industry, CA 91749-1580.

Warranty

This equipment is sold subject to the mutual agreement that it is warranted by us free
from defects of material and of construction, and that our liability shall be limited to
replacing or repairing at our factory (without charge, except for transportation), or at
customer plant at our option, any material or construction in which defects become
apparent within one year from the date of shipment, except in cases where quotations or
acknowledgements provide for a shorter period. Components manufactured by others bear
the warranty of their manufacturer. This warranty does not cover defects caused by wear,
accident, misuse, neglect or repairs other than those performed by Teledyne or an autho­rized service center. We assume no liability for direct or indirect damages of any kind and
the purchaser by the acceptance of the equipment will assume all liability for any damage
which may result from its use or misuse.

We reserve the right to employ any suitable material in the manufacture of our
apparatus, and to make any alterations in the dimensions, shape or weight of any parts, in
so far as such alterations do not adversely affect our warranty.

Important Notice

This instrument provides measurement readings to its user, and serves as a tool by
which valuable data can be gathered. The information provided by the instrument may
assist the user in eliminating potential hazards caused by his process; however, it is
essential that all personnel involved in the use of the instrument or its interface, with the
process being measured, be properly trained in the process itself, as well as all instrumenta­tion related to it.

The safety of personnel is ultimately the responsibility of those who control process
conditions. While this instrument may be able to provide early warning of imminent danger,
it has no control over process conditions, and it can be misused. In particular, any alarm or
control systems installed must be tested and understood, both as to how they operate and
as to how they can be defeated. Any safeguards required such as locks, labels, or redun­dancy, must be provided by the user or specifically requested of Teledyne at the time the
order is placed.

Therefore, the purchaser must be aware of the hazardous process conditions. The
purchaser is responsible for the training of personnel, for providing hazard warning
methods and instrumentation per the appropriate standards, and for ensuring that hazard
warning devices and instrumentation are maintained and operated properly.

Teledyne Analytical Instruments, the manufacturer of this instrument, cannot
accept responsibility for conditions beyond its knowledge and control. No statement
expressed or implied by this document or any information disseminated by the manufactur­er or its agents, is to be construed as a warranty of adequate safety control under the

user’s process conditions.

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Trace Oxygen Analyzer

Specific Model Information

The instrument for which this manual was supplied may incorporate one or
more options not supplied in the standard instrument. Commonly available
options are listed below, with check boxes. Any that are incorporated in the
instrument for which this manual was supplied are indicated by a check mark in
the box.

Instrument Serial Number: __________________________

The instrument with the above serial number has the following
Options:

❏ 3020T-C Three gas inputs, for sample, zero and span gases, with

three solenoid-actuated gas-flow control valves built in.
Valves are automatically synchronized to the analyzer's
electronic control sequences.

❏ 3020T–F Built-in flame arresters for Groups C and D service.
❏ 3020T–G Built-in flame arresters for Groups C and D service, plus

gas-control valves as in –C option, above.

❏ 3020T–H Built-in flame arresters for Group B (hydrogen) service.
❏ 3020T–I Built-in flame arresters for Group B (hydrogen) service,

plus gas-control valves as in –C option, above.

❏ 19" Rack Mount

The 19" Relay Rack Mount units are available with
either one or two series 3000 analyzer Control Units
installed in a standard 19" panel and ready to mount in a
standard rack. See Appendix for details.

❏ Cell Class* ____________________ (L-2C standard).

Enter Class Designation

* See Part II, Chapter 2 and/or any addendum that may be

attached to this manual for cell specifications.

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iii

Model 3020T

1 Introduction

1.1 Overview........................................................................ 1-1

1.2 Typical Applications ....................................................... 1-1

1.3 Main Features of the Analyzer ....................................... 1-1

1.4 Model Designations ....................................................... 1-2

1.5 Operator Interface .......................................................... 1-3

1.5.1 UP/DOWN Switch .................................................. 1-4

1.5.2 ESCAPE/ENTER Switch....................................... 1-4

1.5.3 Displays ................................................................. 1-5

1.6 Recognizing Difference Between LCD & VFD............... 1-5

1.7 Rear Panel Equipment Interface .................................... 1-5

1.7.1 Electrical Connector Panel .................................... 1-5

1.7.2 Gas Connector Panel............................................. 1-7

Table of Contents

2 Operational Theory

2.1 Introduction .................................................................... 2-1

2.2 Micro-Fuel Cell Sensor .................................................. 2-1

2.2.1 Principles of Operation ............................................ 2-1

2.2.2 Anatomy of a Micro-Fuel Cell .................................. 2-2

2.2.3 Electrochemical Reactions ...................................... 2-3

2.2.4 The Eff ect of Pressure.............................................. 2-4

2.2.5 Calibration Characteristics ...................................... 2-4

2.3 Sample System.............................................................. 2-5

2.4 Electronics and Signal Processing ................................ 2-6

2.5 Temperature Control ...................................................... 2-8

3 Installation

3.1 Unpacking the Analyzer................................................. 3-1

3.2 Mounting the Analyzer ................................................... 3-1

3.3 Electrical Connections ................................................... 3-3

3.3.1 Primary Input P ow er............................................... 3-4

3.3.2 Fuse Installation..................................................... 3-4

3.3.3 Analog Outputs ...................................................... 3-4

3.3.4 Alarm Relays ......................................................... 3-6

3.3.5 Digital Remote Cal Inputs ...................................... 3-7

3.3.6 Range ID Relays ................................................... 3-9

3.3.7 Network I/O ............................................................ 3-9

3.3.8 RS-232 Port ........................................................... 3-9

3.3.9 Remote Sensor and Solenoid Valves ....................3-10

3.4 Installing the Micro-Fuel Cell ........................................ 3-11

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Trace Oxygen Analyzer

3.5 Gas Connections .......................................................... 3-12

3.6 Testing the System........................................................ 3-14

4 Operation

4.1 Introduction .................................................................... 4-1

4.2 Using the Controls ......................................................... 4-1

4.2.1 Mode/Function Selection ....................................... 4-2

4.2.1.1 Analysis Mode ............................................... 4-2

4.2.1.2 Setup Mode ................................................... 4-2

4.2.2 Data Entry.............................................................. 4-4

4.2.2.1 ENTER .......................................................... 4-4

4.2.2.2 ESCAPE........................................................ 4-4

4.3 The AUTO-CAL Function............................................... 4-5

4.4 The PWD Function ........................................................ 4-5

4.4.1 Entering the Password........................................... 4-6

4.4.2 Installing or Changing the Password ..................... 4-7

4.5 The LOGOUT Function.................................................. 4-8

4.6 The VERSION Screen ................................................... 4-8

4.7 The SELF TEST Function.............................................. 4-9

4.8 The ZERO and SPAN Functions ................................... 4-9

4.8.1 Zero Cal................................................................. 4-10

4.8.1.1 Auto Mode Zeroing ........................................ 4-10

4.8.1.2 Manual Mode Zeroing.................................... 4-11

4.8.1.3 Cell Failure .................................................... 4-11

4.8.2 Span Cal................................................................ 4-12

4.8.2.1 Auto Mode Spanning ..................................... 4-12

4.8.2.2 Manual Mode Spanning................................. 4-13

4.9 The ALARMS Function.................................................. 4-14

4.10 The RANGE Function.................................................... 4-16

4.10.1 Setting the Analog Output Ranges......................... 4-16

4.10.2 Fixed Range Analysis ............................................ 4-17

4.11 The CONTRAST Function............................................. 4-18

4.12 The STANDBY Function................................................ 4-18

4.13 The

Analysis Mode ........................................................

4-19

Maintenance

5.1 Routine Maintenance..................................................... 5-1

5.2 Major Internal Components............................................ 5-1

5.3 Cell Replacement .......................................................... 5-2

5.3.1 Storing and Handling Replacement Cells ............... 5-3

5.3.2 When to Replace a Cell........................................... 5-3

5.3.3 Removing the Micro-Fuel Cell ................................. 5-4

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Model 3020T

5.3.4 Installing a New Micro-Fuel Cell.............................. 5-6

5.2.5 Cell W arr anty ........................................................... 5-6

5.4 Fuse Replacement ......................................................... 5-7

5.5 System Self Diagnostic Test........................................... 5-7

Appendix

A-1 Specifications ................................................................ A-1

A-2 Recommended 2-Year Spare Parts List ......................... A-3

A-3 Drawing List................................................................... A-4

A-4 Application Notes on Restrictors, Pressures & Flow...... A-4

A-5 Material Safety Data Sheet ............................................ A-5

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Teledyne Analytical Instruments

Trace Oxygen Analyzer Introduction 1

Introduction

1.1 Overview

The Teledyne Analytical Instruments Model 3020T Trace Oxygen
Analyzer is a versatile microprocessor-based instrument for detecting oxygen
at the parts-per-million (ppm) level in a variety of gases. This manual covers
the Model 3020T, trace oxygen, explosion-proof, bulkhead-mount units
only.

1.2 Typical Applications

A few typical applications of the Model 3020T are:

• Monitoring inert gas blanketing

• Air separation and liquefaction

• Chemical reaction monitoring

• Semiconductor manufacturing

• Petrochemical process control

• Quality assurance

• Gas analysis certification.

1.3 Main Features of the Analyzer

The Model 3020T Trace Oxygen Analyzer is sophisticated yet simple
to use. The main features of the analyzer include:

• A 2-line alphanumeric display screen, driven by microprocessor
electronics, that continuously prompts and informs the operator.

• High resolution, accurate readings of oxygen content from low
ppm levels through 25%. Large, bright, meter readout.

• Stainless steel cell block.

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1 Introduction Model 3020T

• Advanced Micro-Fuel Cell, redesigned for trace analysis, has an
expected life of one year.

• Versatile analysis over a wide range of applications.

• Microprocessor based electronics: 8-bit CMOS microprocessor
with 32 kB RAM and 128 kB ROM.

• Three user definable output ranges (from 0-10 ppm through 0­250,000 ppm) allow best match to users process and equipment.

• Air-calibration range for convenient spanning at 20.9 %.

• Auto Ranging allows analyzer to automatically select the proper
preset range for a given measurement. Manual override allows
the user to lock onto a specific range of interest.

• Two adjustable concentration alarms and a system failure alarm.

• Extensive self-diagnostic testing, at startup and on demand, with
continuous power-supply monitoring.

• RS-232 serial digital port for use with a computer or other digital
communication device.

• Four analog outputs: two for measurement (0–1 V dc and
Isolated 4–20 mA dc) and two for range identification.

1.4 Model Designations

3020T: Standard model.
3020T-C: In addition to all standard features, this model also has

separate ports for zero and span gases, and built-in control
valves. The internal valves are entirely under the control of
the 3020T electronics, to automatically switch between gases
in synchronization with the analyzer’s operations

3020T-F: Flame arrestors for Groups C and D installed.
3020T-G: Flame arrestors for Groups C and D, & -C option, installed.
3020T-H: Flame arrestors for Group B (hydrogen) installed.
3020T-I: Flame arrestors for Group B, & -C option, installed.

1-2

All of the above options are available in combination.

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Trace Oxygen Analyzer Introduction 1

1.5 Operator Interface

All controls and displays on the standard 3020T are accessible from
outside the housing. The instrument has two simple operator controls. A
digital meter, an alphanumeric display, and a sample flowmeter give the
operator constant feedback from the instrument. See Figure 1-1. The controls
are described briefly here and in greater detail in chapter 4.

Figure 1-1: Model 3020T Controls, Indicators, and Connectors

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1 Introduction Model 3020T

1.5.1 UP/DOWN Switch

Functions: The UP/DOWN switch is used to select the function to be

performed. Choose UP or DOWN to scroll through the following list of
eleven functions:

• Auto-Cal Set up an automatic calibration sequence.

• PWD Install a password to protect your analyzer setup.

• Logout Locks Setup Mode.

• Version Displays model and version of analyzer.

• Self-Test Runs internal diagnostic program, displays results.

• Span Span calibrate the analyzer.

• Zero Zero calibrate the analyzer.

• Alarms Set the alarm setpoints and attributes.

• Range Set up the 3 user definable ranges for the instrument.

• Contrast Allows adjustment of LCD contrast.

Contrast Function is

• Standby Leaves analyzer powered, but no outputs or displays.

(Refer to Section 1.6)

DISABLED

WARNING: THE POWER CABLE MUST BE DISCONNECTED TO

FULLY REMOVE POWER FROM THE INSTRUMENT.

Subfunctions: Once a Function is entered, the UP/DOWN switch is

used to select between any subfunctions displayed on the VFD screen.

Parameter values: When modifiable values are displayed on the

VFD, the UP/DOWN switch can be used to increment or decrement the
values.

1.5.2 ESCAPE/ENTER Switch

Data Entry: The ESCAPE/ENTER switch is used to input data, from

the alphanumeric VFD screen into the instrument:

• Escape Moves VFD display back to the previous screen in a

series. If none remains, returns to the

Analyze

screen.

• Enter With a Subfunction Selected: Moves VFD display on to

the next screen in a series. If none remains, returns to
the

Analyze

screen.

With a Value Selected: Enters the value into the
analyzer as data. AdvancesVFD to next operation.

1-4

(See Chapter 4 for details.)

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Trace Oxygen Analyzer Introduction 1

1.5.3 Displays

Digital Meter Display: The meter display is a LED device that
produces large, bright, 7-segment numbers that are legible in any lighting. It
produces a continuous readout from 0-10,000 ppm and then switches to a
continuous percent readout from 1-25%. It is accurate across all analysis
ranges without the discontinuity inherent in analog range switching.

Alphanumeric Interface Screen: The VFD screen is an easy-to-use
interface from operator to analyzer. It displays values, options, and messages
that give the operator immediate feedback.

Flowmeter: Monitors the flow of gas past the sensor. Readout is 0.2 to

2.4 standard liters per minute (SLPM).

1.6 Recognizing Difference Between LCD &
VFD

LCD has GREEN background with BLACK characters. VFD has
DARK background with GREEN characters. In the case of VFD - NO
CONTRAST ADJUSTMENT IS NEEDED.

1.7 Equipment Interface

1.7.1 Electrical Connector Panel

The electrical connector panel, shown in Figure 1-2, contains the
electrical connections for external inlets and outlets. The connectors are
described briefly here and in detail in the Installation chapter of this manual.

CAUTION: The power cable must be disconnected to fully

remove power from the instrument.

Access: To access the electrical connector panel, or the sensor block,
the control panel doubles as a door that can be unbolted and swung open.

Electrical Connections: The electrical connections on the electrical
connector panel are described briefly here, and in more detail in chapter 3
Installation.

• Power Connection 115 or 230 V dc, 50 or 60 Hz.

• Analog Outputs 0-1 V dc concentration plus 0-1 V dc

range ID, and isolated 4-20 mA dc plus
4-20 mA dc range ID.

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1 Introduction Model 3020T

• Alarm Connections 2 concentration alarms and 1 system

alarm.

• RS-232 Port Serial digital concentration signal output

and control input.

• Remote Valves Used for controlling external solenoid

valves, if desired.

1-6

Figure 1-2: Electrical Connector Panel

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Trace Oxygen Analyzer Introduction 1

• Remote Sensor Used for external sensor and

thermocouple, if desired.

• Remote Span/Zero Digital inputs allow external control of

analyzer calibration.

• Calibration Contact To notify external equipment that

instrument is being calibrated and
readings are not monitoring sample.

• Range ID Contacts Four separate, dedicated, range relay

contacts. Low, Medium, High, Cal.

• Network I/O Serial digital communications for local

network access. For future expansion.
Not implemented at this printing.

1.7.2 Gas Connector Panel

The gas connector panel, shown in Figure 1-3, contains the gas con­nections for external inlets and outlets. Those that are optional are shown
shaded in the figure. The connectors are described briefly here and in detail
in the Installation chapter of this manual.

Figure 1-3: Model 3020T Gas Connector Panel

• Gas Inlet and Outlet One inlet (must be externally valved)

and one exhaust out.

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1 Introduction Model 3020T

Optional:

• Calibration Gas Ports Separate fittings for zero, span and

sample gas input, plus internal valves for
automatically switching the gases in
sync with the 3020 electronics.

Note: If you require highly accurate Auto-Cal timing, use external

Auto-Cal control where possible. The internal clock in the
Model 3020T is accurate to 2-3 %. Accordingly, internally
scheduled calibrations can vary 2-3 % per day.

1-8

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Trace Oxygen Analyzer Operational Theory 2

Operational Theory

2.1 Introduction

The analyzer is composed of three subsystems:

1. Micro-Fuel Cell Sensor

2. Sample System

3. Electronic Signal Processing, Display and Control

The sample system is designed to accept the sample gas and transport it
through the analyzer without contaminating or altering the sample prior to
analysis. The Micro-Fuel Cell is an electrochemical galvanic device that
translates the amount of oxygen present in the sample into an electrical
current. The electronic signal processing, display and control subsystem
simplifies operation of the analyzer and accurately processes the sampled
data. The microprocessor controls all signal processing, input/output and
display functions for the analyzer.

2.2 Micro-Fuel Cell Sensor

2.2.1 Principles of Operation

The oxygen sensor used in the Model 3020T series is a Micro-Fuel Cell
designed and manufactured by Analytical Instruments. It is a sealed plastic
disposable electrochemical transducer.

The active components of the Micro-Fuel Cell are a cathode, an anode,
and the 15% aqueous KOH electrolyte in which they are immersed. The cell
converts the energy from a chemical reaction into an electrical current in an
external electrical circuit. Its action is similar to that of a battery.

There is, however, an important difference in the operation of a battery
as compared to the Micro-Fuel Cell: In the battery, all reactants are stored
within the cell, whereas in the Micro-Fuel Cell, one of the reactants (oxygen)
comes from outside the device as a constituent of the sample gas being

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2 Operational Theory Model 3020T

analyzed. The Micro-Fuel Cell is therefore a hybrid between a battery and a
true fuel cell. (All of the reactants are stored externally in a true fuel cell.)

2.2.2 Anatomy of a Micro-Fuel Cell

The Micro-Fuel Cell is a cylinder only 1¼ inches in diameter and 1¼
inches thick. It is made of an extremely inert plastic, which can be placed
confidently in practically any environment or sample stream. It is effectively
sealed, although one end is permeable to oxygen in the sample gas. The
other end of the cell is a contact plate consisting of two concentric foil rings.
The rings mate with spring-loaded contacts in the sensor block assembly and
provide the electrical connection to the rest of the analyzer. Figure 2-1
illustrates the external features.

Figure 2-1: Micro-Fuel Cell

Refer to Figure 2-2, Cross Section of a Micro-Fuel Cell, which illus­trates the following internal description.

2-2

Figure 2-2. Cross Section of a Micro-Fuel Cell (not to scale)

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Trace Oxygen Analyzer Operational Theory 2

At the top end of the cell is a diffusion membrane of Teflon, whose
thickness is very accurately controlled. Beneath the diffusion membrane lies
the oxygen sensing element—the cathode—with a surface area almost 4 cm2.
The cathode has many perforations to ensure sufficient wetting of the upper
surface with electrolyte, and it is plated with an inert metal.

The anode structure is below the cathode. It is made of lead and has a
proprietary design which is meant to maximize the amount of metal available
for chemical reaction.

At the rear of the cell, just below the anode structure, is a flexible
membrane designed to accommodate the internal volume changes that occur
throughout the life of the cell. This flexibility assures that the sensing mem­brane remains in its proper position, keeping the electrical output constant.

The entire space between the diffusion membrane, above the cathode,
and the flexible rear membrane, beneath the anode, is filled with electrolyte.
Cathode and anode are submerged in this common pool. They each have a
conductor connecting them to one of the external contact rings on the contact
plate, which is on the bottom of the cell.

2.2.3 Electrochemical Reactions

The sample gas diffuses through the Teflon membrane. Any oxygen in
the sample gas is reduced on the surface of the cathode by the following
HALF REACTION:

O2 + 2H2O + 4e

––

–

––

→ 4OH

––

–

––

(cathode)

(Four electrons combine with one oxygen molecule—in the presence of
water from the electrolyte—to produce four hydroxyl ions.)

When the oxygen is reduced at the cathode, lead is simultaneously
oxidized at the anode by the following HALF REACTION:

Pb + 2OH

––

–

––

→ Pb+2 + H2O + 2e

––

–

––

(anode)

(Two electrons are transferred for each atom of lead that is oxidized.
Therefore it takes two of the above anode reactions to balance one cathode
reaction and transfer four electrons.)

The electrons released at the surface of the anode flow to the cathode
surface when an external electrical path is provided. The current is propor­tional to the amount of oxygen reaching the cathode. It is measured and used
to determine the oxygen concentration in the gas mixture.

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2 Operational Theory Model 3020T

The overall reaction for the fuel cell is the SUM of the half reactions

above, or:

2Pb + O2 → 2PbO

(These reactions will hold as long as no gaseous components capable of
oxidizing lead—such as iodine, bromine, chlorine and fluorine—are present
in the sample.)

The output of the fuel cell is limited by (1) the amount of oxygen in the
cell at the time and (2) the amount of stored anode material.

In the absence of oxygen, no current is generated.

2.2.4 The Effect of Pressure

In order to state the amount of oxygen present in the sample in parts­per-million or a percentage of the gas mixture, it is necessary that the sample
diffuse into the cell under constant pressure.

If the total pressure increases, the rate that oxygen reaches the cathode
through the diffusing membrane will also increase. The electron transfer, and
therefore the external current, will increase, even though the oxygen concen­tration of the sample has not changed. It is therefore important that the
sample pressure at the fuel cell (usually vent pressure) remain relatively
constant between calibrations.

2.2.5 Calibration Characteristics

Given that the total pressure of the sample gas on the surface of the
Micro-Fuel Cell input is constant, a convenient characteristic of the cell is
that the current produced in an external circuit is directly proportional to the
rate at which oxygen molecules reach the cathode, and this rate is directly
proportional to the concentration of oxygen in the gaseous mixture. In other
words it has a linear characteristic curve, as shown in Figure 2-3. Measuring
circuits do not have to compensate for nonlinearities.

In addition, since there is zero output in the absence oxygen, the charac­teristic curve has close to an absolute zero (within ± 1 ppm oxygen). In
practical application, zeroing may still used to compensate for the combined
zero offsets of the cell and the electronics. (The electronics is zeroed auto­matically when the instrument power is turned on.)

2-4

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Trace Oxygen Analyzer Operational Theory 2

Figure 2-3. Characteristic Input/Output Curve for a Micro-Fuel Cell

2.3 Sample System

The sample system delivers gases to the Micro-Fuel Cell sensor from
the analyzer gas panel inlets. Depending on the mode of operation either
sample or calibration gas is delivered.

The Model 3020T sample system is designed and fabricated to ensure
that the oxygen concentration of the gas is not altered as it travels through the
sample system. The sample encounters almost no dead space. This mini­mizes residual gas pockets that can interfere with trace analysis.

The sample system for the standard instrument incorporates ¼ inch tube
fittings for sample inlet and outlet connections at the rear panel. For metric
system installations, 6 mm adapters are supplied with each instrument to be
used if needed. The sample or calibration gas flowing through the system is
monitored by a flowmeter downstream from the cell.

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2 Operational Theory Model 3020T

s

a

o

Figure 2-4 is the flow diagram for the sampling system. In the standard
instrument, calibration gases (zero and span) can be connected directly to the
Sample In port by teeing to the port with appropriate valves. The shaded
portion of the diagram shows the components added when the –C and/or F
options are ordered. The valves, when supplied, are installed inside the
3020T enclosure and are regulated by the instruments internal electronics.
The flame arrestors, when supplied, are installed in the Gas Connector Panel.

Span In

Zero In

Sample In

Solenoid

In vacuum service the
restrictor should b
placed here.

Exhaust O u

Restrictor

In normal service the
restrictor should b
placed here.

Valves

Components in the
the -C option (intern
only and are not sh
diagram abov e

Cell

Figure 2-4: Flow Diagram

2.4 Electronics and Signal Processing

The Model 3020T Trace Oxygen Analyzer uses an 8031 microcontrol­ler with 32 kB of RAM and 128 kB of ROM to control all signal processing,
input/output, and display functions for the analyzer. System power is sup­plied from a universal power supply module designed to be compatible with
most international power sources. See chapter 5 Maintenance for the location
of the power supply and the main electronic PC boards.

The signal processing electronics including the microprocessor, analog
to digital, and digital to analog converters are located on the motherboard at
the bottom of the case. The preamplifier board is mounted on top of the
motherboard as shown in the figure. These boards are accessible after re­moving the access panel. Figure 2-5 is a block diagram of the Analyzer
electronics.

2-6

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Trace Oxygen Analyzer Operational Theory 2

Figure 2-5: Block Diagram of the Model 3020T Electronics

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2 Operational Theory Model 3020T

In the presence of oxygen the cell generates a current. A current to
voltage amplifier converts this current to a voltage, which is amplified in the
second stage amplifier.

The second stage amplifier also supplies temperature compensation for
the oxygen sensor output. This amplifier circuit incorporates a thermistor,
which is physically located in the cell block. The thermistor is a temperature
dependent resistance that changes the gain of the amplifier in proportion to
the temperature changes in the block. This change is inversely proportional
to the change in the cell output due to the same temperature changes. The
result is a signal that is temperature independent. The output from the second
stage amplifier is sent to an 18 bit analog to digital converter controlled by
the microprocessor.

The digital concentration signal along with input from the control panel
is processed by the microprocessor, and appropriate control signals are
directed to the display, alarms and communications port. The same digital
information is also sent to a 12 bit digital to analog converter that produces
the 4-20 mA dc and the 0-1 V dc analog concentration signal outputs, and
the analog range ID outputs.

Signals from the power supply are also monitored, and through the
microprocessor, the system failure alarm is activated if a malfunction is
detected.

2.5 Temperature Control

For accurate analysis this instrument is temperature controlled not to fall
beneath a certain temperature. This temperature is 22oF. This is to prevent
the sensor from freezing in cold environments.

2-8

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Trace Oxygen Analyzer Installation 3

Installation

Installation of the Model 3020T Analyzer includes:

1. Unpacking

2. Mounting

3. Gas connections

4. Electrical connections

5. Installing the Micro-Fuel Cell

6. Testing the system.

3.1 Unpacking the Analyzer

The analyzer is shipped with all the materials you need to install and
prepare the system for operation. Carefully unpack the analyzer and inspect
it for damage. Immediately report any damage to the shipping agent.

3.2 Mounting the Analyzer

The Model 3020T is designed for bulkhead mounting in hazardous
environments. There are four mounting lugs—one in each corner of the
enclosure, as shown in Figure 3-1. The outline drawing, at the back of this
manual, gives the mounting hole size and spacing. The drawing also con­tains the overall dimensions. Do not forget to allow an extra 13/8" for the
hinges.

Be sure to allow enough space in front of the enclosure to swing the
door open—a 16 1/4" radius, as shown in Figure 3-2.

All electrical connections are made via cables which enter the explo­sion-proof housing through ports in its side. No conduit fittings are supplied.
The installer must provide two 3/4" NPT and two 1" NPT adapters and the
appropriate sealing conduit.

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Figure 3-1: Front View of the Model 3020T (Simplified)

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Figure 3-2: Required Front Door Clearance

3.3 Electrical Connections

Figure 3-3 shows the Model 3020T Electrical Connector Panel. There
are terminal blocks for connecting power, communications, and both digital
and analog concentration outputs.

Figure 3-3: Electrical Connector Panel

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For safe connections, ensure that no uninsulated wire extends outside of
the connectors they are attached to. Stripped wire ends must insert com­pletely into terminal blocks. No uninsulated wiring should be able to come in
contact with fingers, tools or clothing during normal operation.

3.3.1 Primary Input Power

The universal power supply requires a 115 or 230 V ac, 50 or 60 Hz
power source. The actual input voltage used must show in the window of the
VOLTAGE SELECTOR switch before the power source is connected. See
Figure 3-4 for detailed connections.

DANGER: Power is applied to the instrument's circuitry as

long as the instrument is connected to the power
source. The Standby function switches power on or
off to the displays and outputs only.

Figure 3-4: Primary Input Power Connections

3.3.2 Fuse Installation

The fuse holders accept 5 x 20 mm, 1.6 A, T type (slow blow) fuses.
Fuses are not installed at the factory. Be sure to install the proper fuse as part
of installation. (See Fuse Replacement in chapter 5, maintenance.)

3.3.3 Analog Outputs

There are eight DC output signal connectors on the ANALOG OUT­PUTS connector block. There are two connectors per output with the polar­ity noted. See Figure 3-5.

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Figure 3-5: Analog Output Connections

The outputs are:

0–1 V dc % of Range: Voltage rises linearly with increasing oxygen, from

0 V at 0 ppm to 1 V at full scale ppm. (Full scale =
100% of programmable range.)

0–1 V dc Range ID: 0.25 V = Low Range, 0.5 V = Medium Range,

0.75 V = High Range, 1 V = Air Cal Range.

4–20 mA dc % Range: Current increases linearly with increasing oxygen,

from 4 mA at 0 ppm to 20 mA at full scale ppm.
(Full scale = 100% of programmable range.)

4–20 mA dc Range ID: 8 mA = Low Range, 12 mA = Medium Range, 16

mA = High Range, 20 mA = Air Cal Range.

Examples:

The analog output signal has a voltage which depends on the oxygen
concentration AND the currently activated analysis range. To relate the
signal output to the actual concentration, it is necessary to know what range
the instrument is currently on, especially when the analyzer is in the
autoranging mode.

The signal output for concentration is linear over the currently selected
analysis range. For example, if the analyzer is set on a range that was defined
as 0–100 ppm O2, then the output would be as shown in Table 3-1.

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Table 3-1: Analog Concentration Output—Example

Voltage Signal Current Signal

ppm O

2

0 0.0 4.0
10 0.1 5.6
20 0.2 7.2
30 0.3 8.8
40 0.4 10.4
50 0.5 12.0
60 0.6 13.6
70 0.7 15.2
80 0.8 16.8
90 0.9 18.4

100 1.0 20.0

Output (V dc) Output (mA dc)

To provide an indication of the range, a second pair of analog output
terminals are used. They generate a steady preset voltage (or current when
using the current outputs) to represent a particular range. Table 3-2 gives the
range ID output for each analysis range.

Table 3-2: Analog Range ID Output—Example

Range Voltage (V) Current (mA)

LO 0.25 8
MED 0.50 12
HI 0.75 16
CAL (0-25%) 1.00 20

3.3.4 Alarm Relays

There are three alarm-circuit connectors on the alarm relays block
(under RELAY OUTPUTS) for making connections to internal alarm relay
contacts. Each provides a set of Form C contacts for each type of alarm.
Each has both normally open and normally closed contact connections. The
contact connections are indicated by diagrams on the connector panel. They
are capable of switching up to 3 amperes at 250 V ac into a resistive load.
See Figure 3-6.

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Figure 3-6: Types of Relay Contacts

The connectors are:

Threshold Alarm 1: • Can be configured as high (actuates when concen-

tration is above threshold), or low (actuates when
concentration is below threshold).

• Can be configured as failsafe or nonfailsafe.

• Can be configured as latching or nonlatching.

• Can be configured out (defeated).

Threshold Alarm 2: • Can be configured as high (actuates when concen-

tration is above threshold), or low (actuates when
concentration is below threshold).

• Can be configured as failsafe or nonfailsafe.

• Can be configured as latching or nonlatching.

• Can be configured out (defeated).

System Alarm: Actuates when DC power supplied to circuits is

unacceptable in one or more parameters. Permanently
configured as failsafe and latching. Cannot be de­feated. Actuates if self test fails.

To reset a System Alarm during installation, discon­nect power to the instrument and then reconnect it.

Further detail can be found in chapter 4, section 4-5.

3.3.5 Digital Remote Cal Inputs

Remote Zero and Span Inputs: The REMOTE SPAN and RE-

MOTE ZERO inputs are on the DIGITAL INPUT terminal block. They
accept 0 V (OFF) or 24 V dc (ON) for remote control of calibration. (See
Remote Calibration Protocol below.)

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ZERO: Floating input. 5 to 24 V input across the + and – terminals

puts the analyzer into the
grounded at the source of the signal. 0 to 1 volt across the
terminals allows
synchronous signal must open and close the external zero
valve appropriately. See 3.3.9 Remote Sensor and Solenoid
Valves. (With the –C option, the internal valves automatically
operate synchronously.)

SPAN: Floating input. 5 to 24 V input across the + and – terminals

puts the analyzer into the
grounded at the source of the signal. 0 to 1 volt across the
terminals allows
synchronous signal must open and close the external span
valve appropriately. See 3.3.9 Remote Sensor and Solenoid
Valves. (With the –C option, the internal valves automatically
operate synchronously.)

Zero

Span

Zero

mode. Either side may be

mode to terminate when done. A

Span

mode. Either side may be

mode to terminate when done. A

Cal Contact: This relay contact is closed while analyzer is spanning

and/or zeroing. (See Remote Calibration Protocol below.)

Remote Calibration Protocol: To properly time the Digital Remote

Cal Inputs to the Model 3020T Analyzer, the customer's controller must
monitor the CAL CONTACT relay.

When the contact is OPEN, the analyzer is analyzing, the Remote Cal

Inputs are being polled, and a zero or span command can be sent.

When the contact is CLOSED, the analyzer is already calibrating. It

will ignore your request to calibrate, and it will not remember that request.

Once a zero or span command is sent, and acknowledged (contact
closes), release it. If the command is continued until after the zero or span is
complete, the calibration will repeat and the Cal Relay Contact (CRC) will
close again.

For example:

1) Test the CRC. When the CRC is open, Send a zero command
until the CRC closes (The CRC will quickly close.)

2) When the CRC closes, remove the zero command.

3) When CRC opens again, send a span command until the CRC
closes. (The CRC will quickly close.)

4) When the CRC closes, remove the span command.

When CRC opens again, zero and span are done, and the sample is

being analyzed.

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Note: The remote probe connections (paragraph 3.3.9) provide

signals to ensure that the zero and span gas valves will be
controlled synchronously. If you have the –C Internal valve
option—which includes additional zero and span gas inputs—
the 3020T automatically regulates the zero, span and sample
gas flow.

3.3.6 Range ID Relays

There are four dedicated RANGE ID CONTACT relays. The first
three ranges are assigned to relays in ascending order—Low range is as­signed to RANGE 1 ID, Medium range is assigned to RANGE 2 ID, and
High range is assigned to RANGE 3 ID. RANGE 4 ID is reserved for the
Air Cal Range (25%).

3.3.7 Network I/O

A serial digital input/output for local network protocol. At this printing,
this port is not yet functional. It is to be used in future versions of the instru­ment.

3.3.8 RS-232 Port

The digital signal output is a standard RS-232 serial communications
port used to connect the analyzer to a computer, terminal, or other digital
device. The pinouts are listed in Table 3-3.

Table 3-3: RS-232 Signals

RS-232 Sig RS-232 Pin Purpose

DCD 1 Data Carrier Detect

RD 2 Received Data

TD 3 Transmitted Data

DTR 4 Data Terminal Ready

COM 5 Common

DSR 6 Data Set Ready

RTS 7 Request to Send
CTS 8 Clear to Send

RI 9 Ring Indicator

The data sent is status information, in digital form, updated every two
seconds. Status is reported in the following order:

• The concentration in ppm or percent

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• The range in use (HI, MED, LO)

• The span of the range (0-100 ppm, etc)

• Which alarms—if any—are disabled (AL–x DISABLED)

• Which alarms—if any—are tripped (AL–x ON).

Each status output is followed by a carriage return and line feed.

Three input functions using RS-232 have been implemented to date.

They are described in Table 3-4.

Table 3-4: Commands via RS-232 Input

Command Description
as<enter> Immediately starts an autospan.
az<enter> Immediately starts an autozero.
st<enter> Toggling input. Stops/Starts any status message output from

the RS-232, until st<enter> is sent again.

The RS-232 protocol allows some flexibility in its implementation.
Table 3-5 lists certain RS-232 values that are required by the 3020T imple­mentation.

Table 3-5: Required RS-232 Options

Parameter Setting

Baud 2400

Byte 8 bits

Parity none

Stop Bits 1

Message Interval 2 seconds

3.3.9 Remote Sensor and Solenoid Valves

The 3020T is a single-chassis instrument, which has its own sensor and,
in the –C option, its own gas-control solenoid valves. The REMOTE SEN­SOR connector is not used, and the SOLENOID RETURN connectors are
used (without the –C option) to synchronize external gas control valves, if
desired. See Figure 3-7.

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Figure 3-7: Remote Solenoid Return Connector Pinouts

The voltage from these outputs is nominally 0 V for the OFF and
15 V dc for the ON conditions. The maximum combined current that can be
pulled from these output lines is 100 mA. (If two lines are ON at the same
time, each must be limited to 50 mA, etc.) If more current and/or a different
voltage is required, use a relay, power amplifier, or other matching circuitry
to provide the actual driving current.

In addition, each individual line has a series FET with a nominal ON
resistance of 5 ohms (9 ohms worst case). This could limit the obtainable
voltage, depending on the load impedance applied. See Figure 3-8.

Figure 3-8: FET Series Resistance

3.4 Installing the Micro-Fuel Cell

The Micro-Fuel Cell is not installed in the cell block when the
instrument is shipped. It must be installed before the analyzer is placed in
service.

Once it is expended, or if the cell is exposed to air for too long, the
Micro-Fuel Cell will need to be replaced. The cell could also require replace­ment if the instrument has been idle for too long.

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When the micro-Fuel Cell needs to be installed or replaced, follow the

procedures in chapter 5, Maintenance, for removing and installing cells.

3.5 Gas Connections

Before using this instrument, it should be determined if the unit will be
used for pressurized service or vacuum service and low pressure applica­tions. Inspect the restrictor kit that came with the unit. The kit consist of two
restrictors and a union for 1/4” diameter tubing. Notice that the two 1 3/4”
long, 1/4” diameter tubing are restrictors. It has an open end and a closed
end with a small circular orifice. The restrictor without the blue sticker is for
;ow pressure and vacuum service. For high pressure (2 to 50 psig) applica­tions, use the restrictor that has a blue sticker on the body.

For pressurized service, use the restrictor without the blue dot and union
from the restrictor kit and attach it to the Sample In port. The small circular
orifice should face away from the back of the unit (against the direction of
gas flow). Use the restrictor without the blue dot sticker in the same manner
for low pressure applications (less than 5 psig).

For vacuum service (5-10 in Hg), use the restrictor without the blue dot
sticker and union but attach it to the Exhaust Out port. The small circular
orifice should face toward the back of the unit (against the direction of gas
flow).

Remove the blue sticker from the restrictor before using.

WARNING: Operating the unit without restrictors can cause damage to t

the micro-fuel cell.

Figure 3-9 is an illustration of the Gas Connector Panel. Optional gas
connections are shown in a shaded block.

The unit is manufactured with 1/4 inch tube fittings only. Adapters must
be used for metric tubing. (At least 6 mm is recommended.)

For a safe connection:

1. Insert the tube into the tube fitting, and finger-tighten the nut until
the tubing cannot be rotated freely, by hand, in the fitting. (This
may require an additional 1/8 turn beyond finger-tight.)

2. Hold the fitting body steady with a backup wrench, and with
another wrench rotate the nut another 11/4 turns.

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Figure 3-9: Gas Connector Panel

SAMPLE IN: In the standard model, gas connections are made at the

SAMPLE IN and EXHAUST OUT connections. Calibration gases must be

Tee'd into the Sample inlet with appropriate valves.

The gas pressure in should be reasonably regulated. Pressures between
3 and 40 psig are acceptable as long as the pressure, once established, will
keep the front panel flowmeter reading in an acceptable range (0.1 to 2.4
SLPM). Exact figures will depend on your process.

If greater flow is required for improved response time, install a bypass
in the sampling system upstream of the analyzer input.

Note: If the unit is for vacuum service, the above numbers apply

instead to the vacuum at the EXHAUST OUT connector, de­scribed below, with minus signs before the pressure readings.

ZERO IN and SPAN IN: These are additional ports for inputting span
gas and zero gas. There are electrically operated valves inside for automatic
switching between sample and calibration gases. These valves are com­pletely under control of the 3020T Electronics. They can be externally
controlled only indirectly through the Remote Cal Inputs, described below.

Pressure, flow, and safety considerations are the same as prescribed for
the SAMPLE IN inlet, above.

EXHAUST OUT: Exhaust connections must be consistent with the
hazard level of the constituent gases. Check Local, State, and Federal laws,
and ensure that the exhaust stream vents to an appropriately controlled area if
required.

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Note: If the unit is for vacuum service, see

pressure/flow considerations.

Sample In

3.6 Testing the System

Before plugging the instrument into the power source:

• Check the integrity and accuracy of the gas connections. Make
sure there are no leaks.

• Check the integrity and accuracy of the electrical connections.
Make sure there are no exposed conductors

• Check that sample pressure is between 3 and 40 psig, according
to the requirements of your process.

• Check that the voltage selector switch on the Electrical
Connector Panel is in the appropriate position for your power
source.

Power up the system, and test it by performing the following

operations:

1. Repeat the Self-Diagnostic Test as described in chapter 4, section

4.3.5.

, above, for gas

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Operation

4.1 Introduction

Once the analyzer has been installed, it can be configured for your

application. To do this you will:

• Establish and start an automatic calibration cycle, if desired.
(Electrically operated valves required.)

• Define the three user selectable analysis ranges. Then choose
autoranging or select a fixed range of analysis, as required.

• Calibrate the instrument.

• Set alarm setpoints, and modes of alarm operation (latching,
failsafe, etc).

• Establish a security password, if desired, requiring Operator to
log in.

Before you configure your 3020T these default values are in effect:

Ranges: LO = 100 ppm, MED = 1000 ppm, HI = 10,000 ppm.
Auto Ranging: ON
Alarm Relays: Defeated, 1000 ppm, HI, Not failsafe, Not latching.
Zero: Auto, every 0 days at 0 hours.
Span: Auto, at 209,000 ppm, every 0 days at 0 hours.

If you choose not to use password protection, the default password is
displayed on the VFD screen only if you have entered the logout or pass­word function, as explained later. Then, you must enter the default password
for access.

4.2 Using the Controls

To get the proper response from these controls, turn the control toward
the desired action (ESCAPE or ENTER—DOWN or UP), and then release it.
Turn-and-release once for each action. For example, turn-and-release twice

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4 Operation Model 3020T

toward UP to move the VFD screen two selections upwards on the list of
options (menu).

The item that is between arrows on the screen is the item that is cur­rently selectable by choosing ENTER (turn-and-release toward ENTER with
the ESCAPE/ENTER control).

In these instructions, to ENTER means to turn-and-release toward
ENTER, and To ESCAPE means to turn-and-release towards ESCAPE. To
scroll UP (or scroll DOWN) means to turn-and-release toward UP (or
DOWN) as many times as necessary to reach the required menu item.

4.2.1 Mode/Function Selection

When the analyzer is first powered up, and has completed its initializa­tion and self diagnostics, ESCAPE toggles the instrument between the
ANALYZE screen (Analysis Mode) and the MAIN MENU screen (Setup
Mode). The ANALYZE screen is the only screen of the Analysis Mode.

The MAIN MENU screen is the top level in a series of screens used in
the Setup Mode to configure the analyzer for the specific application. The
DOWN/UP commands scroll through the options displayed on the VFD
screen. The selectable option appears between arrows. When you reach the
desired option by scrolling, ENTER the selection as described below.

ESCAPE takes you back up the hierarchy of screens until you reach the
MAIN MENU again. ESCAPING any further just toggles between the
MAIN MENU and the ANALYZE screen.

4.2.1.1 Analysis Mode

This is the normal operating mode. The analyzer monitors the oxygen
content of the sample, displays the percent of oxygen, and warns of any
alarm conditions. Either control switches you to Setup Mode. Setup Mode
switches back to Analyze Mode if no controls are used for more than 5 s.

4.2.1.2 Setup Mode

The MAIN MENU consists of 11 functions you can use to customize
the operations of the analyzer. Figure 4-1 shows the functions available with
the Model 3020T. They are listed here with brief descriptions:

4-2

1 AUTO-CAL: Used to define and/or start an automatic calibration

sequence.

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Contrast Function is

(Refer to Section 1.6)

Figure 4-1: Modes and Functions

2 PWD: Used to establish password protection or change the

existing password.

DISABLED

3 LOGOUT: Logging out prevents unauthorized tampering with

the analyzer settings.

4 VERSION: Displays Manufacturer, Model, and Software version

of the instrument.

5 SELF-TEST: The instrument performs a self-diagnostic routine

to check the integrity of the power supply, output boards and
amplifiers.

6 SPAN: Set up and/or start a span calibration.
7 ZERO: start a zero calibration.
8 ALARMS: Used to set the alarm setpoints and determine

whether each alarm will be active or defeated, HI or LO acting,
latching or not, and failsafe or not.

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9 RANGE: Used to set up three analysis ranges that can be

switched automatically with auto-ranging or used as individual
fixed ranges.

10 STANDBY: Remove power to outputs and displays, but

maintain power to internal circuitry.

Any function can be selected at any time. Just scroll through the MAIN
MENU with the DOWN/UP control to the appropriate function, and ENTER
it. The analyzer will immediately start that function, unless password
restrictions have been assigned. (Password assignment is explained further
on.)

All of these functions are described in greater detail in the procedures
starting in section 4.3. The VFD screen texts used to illustrate the procedures
are reproduced in a Monospaced type style.

4.2.2 Data Entry

4.2.2.1 ENTER

When the item you want from the VFD screen appears between the
arrows on the VFD screen, ENTER it using the ESCAPE/ENTER control.

When the selected option is a function or subfunction, ENTER moves
to the VFD screen for that function or subfunction.

When the selected option is a modifiable item, the DOWN/UP control
can be used to increment or decrement that modifiable item to the value or
action you want. Then you ENTER the item.

ENTER then puts you into the next field to continue programming. If
the screen is completed, ENTER takes you to the next screen in the process,
or if the process is completed, ENTER takes you back to the ANALYZE
screen.

4.2.2.2 ESCAPE

If you do not wish to continue a function, you can abort the session
with a turn-and-release toward ESCAPE. Escaping a function takes the
analyzer back to the previous screen, or to the ANALYZE Function, depend­ing on the function escaped.

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4. 3 The AUTO-CAL Function

When proper automatic valving is connected (see chapter 3, installa-

tion), the Analyzer can cycle itself through a sequence of steps that automati-

cally zero and span the instrument.

Note: If you require highly accurate AUTO-CAL timing, use external

AUTO-CAL control where possible. The internal clock in the

Model 3020T is accurate to 2-3 %. Accordingly, internally
scheduled calibrations can vary 2-3 % per day.

To setup an AUTO-CAL cycle:
Scroll to AUTO-CAL, and ENTER. A new screen for Span/Zero set

appears.

Span OFF Nxt: 0d 0h

Zero OFF Nxt: 0d 0h

If SPAN (or ZERO) is not between the arrows, scroll with DOWN/UP

control to SPAN (or ZERO), then ENTER. (You won’t be able to set OFF to
ON if a zero interval is entered.) A Span Every ... (or Zero Every ...)
screen appears.

Span Every 0 d

Start 0 h from now

Use DOWN/UP control to set an interval value, and ENTER. Then use

DOWN/UP to set a start-time value, and ENTER.

To turn ON the Span and/or Zero cycles (to activate AUTO-CAL):

Scroll to AutoCal, and ENTER it again.

Span OFF Nxt: 0d 0h

Zero OFF Nxt: 0d 0h

When the Span/Zero values screen appears, use the scroll DOWN to

blink the OFF/ON field of the SPAN (or ZERO) function. Use DOWN/UP
to set the OFF/ON field to ON. You can now turn these fields ON because
there is a nonzero span interval defined.

4.4 The PWD (Password) Function

Security can be established by choosing a 5 digit password from the
standard ASCII character set. If you decide NOT to employ password
security, use the default password TETAI. This password will be displayed
automatically by the microprocessor. The operator just ENTERs it to be
allowed total access to the instrument’s features.

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4 Operation Model 3020T

Once a unique password is assigned and activated, the operator MUST

enter the UNIQUE password to gain access to any of the set-up functions
(except to enter the password). However, the instrument will continue to
analyze sample gas and report on alarm conditions without entering the
password.

• Only one password can be defined.

• After a password is assigned, the operator must log out to

activate it. Until then, anyone can continue to operate the
instrument without entering the new password.

• To defeat the security after a unique password is activated, the
password must be changed back to TETAI.

NOTE: If you use password security, it is advisable to keep a copy of

the password in a separate, safe location.

4.4.1 Entering the Password

To install a new password or change a previously installed password,
you must key in and ENTER the old password first. If the default password
is in effect, issuing the ENTER command will enter the default TETAI pass­word for you.

Scroll to PWD, and ENTER to select the password function. Either the
TETAI default password or AAAAA place-holder password for an existing
password will appear on screen depending on whether or not a password has
been previously installed.

T E T A I

Enter PWD

or

A A A A A

Enter PWD

The screen prompts you to enter the current password. If you are not
using password protection, ENTER to accept TETAI as the default password.
If a password has been previously installed, enter the password using EN­TER to scroll through the letters, and the DOWN/UP keys to change the
letters to the proper password. The last ENTER enters the password.

If the password is accepted, the screen will indicate that the password
restrictions have been removed and you have clearance to proceed.

4-6

PWD Restrictions

Removed

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In a few seconds, if you do not ESCAPE, you will be given the oppor-

tunity to change this password or keep it and go on.

Change Password?

<ENT>=Yes <ESC>=No

ESCAPE to move on, or proceed as in Changing the Password, below.

4.4.2 Installing or Changing the Password

If you want to install a password, or change an existing password:
Proceed as above in Entering the Password, until you are given the opportu-
nity to change the password:

Change Password?

<ENT>=Yes <ESC>=No

ENTER to change the password (to change either the default TETAI or
the previously assigned password), or ESCAPE to keep the existing pass­word and move on.

If you choose ENTER to change the password, the password assign­ment screen appears.

T E T A I

<ENT> To Proceed

or

A A A A A

<ENT> To Proceed

Enter the password using ENTER to scroll through the existing pass­word letters, and DOWN/UP to change the letters to the new password. The
full set of 94 characters available for password use are shown in the table
below.

Characters Available for Password Definition:

ABCDEFGHIJ

KLMNOPQRST

UVWXYZ[¥]^

_`abcdefgh

ijklmnopqr

stuvwxyz{|

} → !"#$%&'(

)*+'-./012

3456789:;<

=>?@

When you have finished typing the new password, the last ENTER
enters it. A verification screen appears. The screen will prompt you to retype
your password for verification.

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A A A A A

Retype PWD To Verify

Wait a moment for the entry (<ENT>) screen. You will be given

clearance to proceed.

A A A A A

<ENT> TO Proceed

ENTER the letters of your new password. Your password will be stored
in the microprocessor and the system will immediately switch to the ANA­LYZE screen, and you now have access to all instrument functions.

If all alarms are defeated, the ANALYZE screen appears as:

0.0 ppm Anlz

Range: 0  100

If an alarm is tripped, the second line will change to show which alarm
it is:

0.0 ppm Anlz

AL1

NOTE:If you log off the system using the LOGOUT function in the

MAIN MENU, you will now be required to re-enter the pass­word to gain access to
functions.

SPAN, ZERO, ALARM, and RANGE

4.5 The LOGOUT Function

By entering LOGOUT, you effectively log off the instrument, leaving
the system protected against tampering until the password is reentered. To
log out, scroll to place the LOGOUT function between the arrows, and
ENTER to log out. The screen will display the message:

Protected Until

Password Reentered

4.6 The VERSION Screen

Scroll through the MAIN MENU to VERSION, and ENTER. The
screen displays the manufacturer, model, and software version information.

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Trace Oxygen Analyzer Operation 4

4. 7 The SELF-TEST Function

The Model 3020T has a built-in self-testing diagnostic routine. Prepro­grammed signals are sent through the power supply, output board and sensor
circuit. The return signal is analyzed, and at the end of the test the status of each
function is displayed on the screen, either as OK or as a number between 1 and

3. (See System Self Diagnostic Test in chapter 5 for number code.)

The self diagnostics are run automatically by the analyzer whenever the
instrument is turned on, but the test can also be run by the operator at will. To
initiate SELF-TEST during operation:

Use the DOWN/UP control to scroll through the MAIN MENU to SELF-
TEST. The screen will follow the running of the diagnostic.

RUNNING DIAGNOSTIC

Testing Preamp  83

During preamp testing there is a countdown in the lower right corner of
the screen. When the testing is complete, the results are displayed.

Power: OK Analog: OK

Preamp: 3

The module is functioning properly if it is followed by OK. A number
indicates a problem in a specific area of the instrument. Refer to Chapter 5
Maintenance for number-code information. The results screen alternates for a
time with:

Press Any Key

To Continue...

Then the analyzer returns to the ANALYZE screen.

4.8 The ZERO and SPAN Functions

Zeroing is not required in order to achieve the published
accuracy specification of this unit.

Zeroing will eliminate offset error contributed by sensor, elec­tronics, and internal and external sampling system and im­prove performance beyond published specification limits.

The analyzer is calibrated using zero and span gases.

Any suitable oxygen-free gas can be used for zero gas as long as it is
known to be oxygen free and does not react adversely with the sample system.

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4 Operation Model 3020T

Although the instrument can be spanned using air, a span gas with a
known oxygen concentration in the range of 70–90% of full scale of the
range of interest is recommended. Since the oxygen concentration in air is
209,000 ppm, the cell can take a long time to recover if the instrument is
used for trace oxygen analysis immediately following calibration in air.

Connect the calibration gases to the analyzer according to the instruc­tions given in section 3.5, Gas Connections, observing all the prescribed
precautions.

Shut off the gas pressure before connecting it to the analyzer, and
be sure to limit the pressure to 40 psig or less when turning it back on.

Readjust the gas pressure into the analyzer until the flowrate (as read on
the analyzer’s SLPM flowmeter) settles between 0.5 and 2.4 SLPM (ap­proximately 1-5 scfh).

If you are using password protection, you will need to enter your
password to gain access to either of these functions. Follow the instructions
in section 4.4 to enter your password. Once you have gained clearance to
proceed, you can ENTER the ZERO or SPAN function.

4.8.1 Zero Cal

The ZERO function on the MAIN MENU is used to enter the zero
calibration function. Zero calibration can be performed in either the auto­matic or manual mode. In the automatic mode, an internal algorithm com­pares consecutive readings from the sensor to determine when the output is
within the acceptable range for zero. In the manual mode, the operator
determines when the reading is within the acceptable range for zero.

Make sure the zero gas is connected to the instrument.

If you get a CELL FAILURE message skip to section 4.8.1.3.

4.8.1.1 Auto Mode Zeroing

Select ZERO to enter the ZERO function. The ZERO screen allows
you to select whether the zero calibration is to be performed automatically or
manually. Use the DOWN/UP control to toggle between AUTO and MAN
zero settling. Stop when AUTO appears on the display.

Zero: Settling: AUTO

<ENT> To Begin

ENTER to begin zeroing.

4-10

#### PPM Zero

Slope=#### ppm/s

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Trace Oxygen Analyzer Operation 4

The beginning zero level is shown in the upper left corner of the dis­play. As the zero reading settles, the screen displays and updates information
on Slope (unless the Slope starts within the acceptable zero range and does
not need to settle further).

Then, and whenever Slope is less than 0.08 for at least 3 minutes,
instead of Slope you will see a countdown: 1 Left, 0 Left, and so fourth.
These are two steps in the zeroing process that the system must complete,
AFTER settling, before it can go back to ANALYZE.

#### PPM Zero

1 Left=### ppm/s

The zeroing process will automatically conclude when the output is
within the acceptable range for a good zero. Then the analyzer automatically
returns to the ANALYZE screen.

4.8.1.2 Manual Mode Zeroing

ENTER the ZERO function. The screen that appears allows you to
select between automatic or manual zero calibration. Use DOWN/UP to
toggle between AUTO and MAN zero settling. Stop when MAN appears on
the display.

Zero: Settling: Man

<ENT> To Begin

ENTER to begin the zero calibration. After a few seconds the first of
five zeroing screens appears. The number in the upper left hand corner is the
first-stage zero offset. The microprocessor samples the output at a predeter­mined rate. It calculates the differences between successive samplings and
displays the rate of change as Slope= a value in parts per million per second
(ppm/s).

#### ppm Zero

Slope=#### ppm/s

NOTE:It takes several seconds for the true

Wait about 10 seconds. Then, wait until
close to zero before using ENTER to finish zeroing.

SlopeSlope

Slope value to display.

SlopeSlope

SlopeSlope

Slope is sufficiently

SlopeSlope

Generally, you have a good zero when Slope is less than 0.05 ppm/s
for about 30 seconds. When Slope is close enough to zero, ENTER it. In a
few seconds, the screen will update.

Once zero settling completes, the information is stored in the
microprocessor, and the instrument automatically returns to the ANALYZE
screen.

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4 Operation Model 3020T

4.8.1.3 Cell Failure

Cell failure in the 3020T is usually associated with inability to zero the
instrument down to a satisfactorily low ppm reading. When this occurs, the
3020T system alarm trips, and the VFD displays a failure message.

#.# ppm Anlz

CELL FAIL/ ZERO HIGH

Before replacing the cell:

a. Check for leaks downstream from the cell, where oxygen may be

leaking into the system.
b. Check your span gas to make sure it is within specifications.
c. If there are no leaks and the span gas is OK, replace the cell as

described in chapter 5, Maintenance.
d. After correcting the condition, reset the Cell Fail Alarm by taking

the analyzer into, and then back out of, STANDBY.

4.8.2 Span Cal

SPAN is used to span calibrate the analyzer. Span calibration can be

performed using the automatic mode, where an internal algorithm compares
consecutive readings from the sensor to determine when the output matches
the span gas concentration. Span calibration can also be performed in
manual mode, where the operator determines when the span concentration
reading is acceptable and manually exits the function.

4.8.2.1 Auto Mode Spanning

Scroll to SPAN, and ENTER the SPAN function. The screen that

appears allows you to select whether the span calibration is to be performed
automatically or manually. Use the DOWN/UP control to toggle between
AUTO and MAN span settling. Stop when AUTO appears on the display.

Span: Settling: AUTO

<ENT> For Next

Use ENTER to move to the next screen.

Span Val: 209000.00

<ENT>Span <UP>Mod #

Use DOWN/UP to start changing the oxygen-concentration. Use

ESCAPE/ENTER to blink the digit you are going to modify. Use DOWN/UP
again to change the value of the selected digit. When you have finished

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Trace Oxygen Analyzer Operation 4

typing in the concentration of the span gas you are using, repeatedly select
ENTER until the rightmost digit is reached, then, the next ENTER will exit the
Span Val field. One more ENTER will enter the new span value, bring up the
next screen, and start the span calibration.

#### ppm Span

Slope=#### ppm/s

The beginning span value is shown in the upper left corner of the
display. As the span reading settles, the screen displays and updates informa­tion on Slope. Spanning automatically ends when the span output corre­sponds, within tolerance, to the value of the span gas concentration. Then the
instrument automatically returns to the ANALYZE mode.

4.8.2.2 Manual Mode Spanning

ENTER SPAN from the MAIN MENU to start the SPAN function.
The screen that appears allows you to select whether the span calibration is
to be performed automatically or manually.

Span: Settling:MAN

<ENT> For Next

Use DOWN/UP to toggle between AUTO and MAN span settling. Stop
when MAN appears on the display. Use ENTER to move to the next screen.

Span Val: 209000.00

<ENT>Span <UP>Mod #

Use UP to permit modification (Mod #) of span value.

Use ESCAPE/ENTER to choose the digit, and use DOWN/UP to
choose the value of the digit.

When you have finished typing in the concentration of the span gas you
are using, repeatedly select ENTER until the rightmost digit is reached, then, the
next ENTER will exit the Span Val field. One more ENTER will enter the new
span value, bring up the next screen, and start the span calibration.

Once the span has begun, the microprocessor samples the output at a
predetermined rate. It calculates the difference between successive samplings
and displays this difference as Slope on the screen. It takes several seconds
for the first Slope value to display. Slope indicates rate of change of the Span
reading. It is a sensitive indicator of stability.

#### % Span

Slope=#### ppm/s

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4 Operation Model 3020T

When the Span value displayed on the screen is sufficiently stable,
ENTER it. (Generally, when the Span reading changes by 1 % or less of the
full scale of the range being calibrated for a period of ten minutes it is suffi­ciently stable.) Once you ENTER it, the Span reading changes to the correct
value. The instrument then automatically enters the ANALYZE function.

4.9 The ALARMS Function

The Model 3020T is equipped with 2 fully adjustable concentration
alarms and a system failure alarm. Each alarm has a relay with a set of form
“C" contacts rated for 3 amperes resistive load at 250 V ac. See Figure in
Chapter 3, Installation and/or the Interconnection Diagram included at the
back of this manual for relay terminal connections.

The system failure alarm has a fixed configuration described in chapter
3 Installation.

The concentration alarms can be configured from the front panel as
either high or low alarms by the operator. The alarm modes can be set as

latching or non-latching, and either failsafe or non-failsafe, or, they can be
defeated altogether. The setpoints for the alarms are also established using

this function.

Decide how your alarms should be configured. The choice will depend
upon your process. Consider the following four points:

1. Which if any of the alarms are to be high alarms, and which if
any are to be low alarms?

Setting an alarm as HIGH triggers the alarm when the oxygen
concentration rises above the setpoint. Setting an alarm as LOW
triggers the alarm when the oxygen concentration falls below the
setpoint.

Decide whether you want the alarms to be set as:

• Both high (high and high-high) alarms, or

• One high and one low alarm, or

• Both low (low and low-low) alarms.

2. Are either or both of the alarms to be configured as failsafe?
In failsafe mode, the alarm relay de-energizes in an alarm

condition. For non-failsafe operation, the relay is energized in an
alarm condition. You can set either or both of the concentration
alarms to operate in failsafe or non-failsafe mode.

4-14

3. Are either of the alarms to be latching?
In latching mode, once the alarm or alarms trigger, they will

remain in the alarm mode even if process conditions revert back

Teledyne Analytical Instruments

Trace Oxygen Analyzer Operation 4

to non-alarm conditions. This mode requires an alarm to be
recognized before it can be reset. In the non-latching mode, the
alarm status will terminate when process conditions revert to non­alarm conditions.

4. Are either of the alarms to be defeated?
The defeat alarm mode is incorporated into the alarm circuit so

that maintenance can be performed under conditions which
would normally activate the alarms.

The defeat function can also be used to reset a latched alarm.
(See procedures, below.)

If you are using password protection, you will need to enter your
password to access the alarm functions. Follow the instructions in section 4.4
to enter your password. Once you have clearance to proceed, ENTER the
ALARM function.

AL1 AL2

Choose Alarm

Use the DOWN/UP control to blink your choice of alarm, AL-1 or
AL-2. Then ENTER to move to the next screen.

AL1 1000 ppm HI

DftN FsN LtchN

Five parameters can be changed on this screen.

• Value of the alarm setpoint: AL–1 #### ppm (oxygen)

• Out-of-range direction: HI or LO

• Defeated? (Yes/No): Dft–Y/N

• Failsafe? (Yes/No): Fs–Y/N

• Latching? (Yes/No): Ltch–Y/N.

• To define the setpoint, use ENTER to blink AL–1 ####. Then
use the DOWN/UP control to change the number. Holding the
control on the DOWN or UP position, while the number changes,
speeds up the incrementing or decrementing. (Remember, the
setpoint units are always ppm O2.)

• To set the other parameters use ENTER to blink the desired
parameter. Then use DOWN/UP to change the parameter.

• Once the parameters for the alarm have been set, ENTER the
ALARM function again, and repeat this procedure for next alarm.

• To reset a latched alarm, go to Dft and then assert either DOWN
two times or UP two times. (Toggle it to

Teledyne Analytical Instruments

YY

Y and then back to

YY

N.N.

N.)

N.N.

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4 Operation Model 3020T

–OR –

Go to Ltch and then assert either DOWN two times or UP two
times. (Toggle it to

NN

N and back to

NN

Y.Y.

Y.)

Y.Y.

4.10 The RANGE Function

The RANGE function allows the operator to program up to three

concentration ranges to correlate with the DC analog outputs. If no ranges
are defined by the user, the instrument defaults to:

Low = 0–100 ppm
Med = 0–1,000 ppm
High = 0–10,000 ppm.

The Model 3020T is set at the factory to default to autoranging. In this
mode, the microprocessor automatically responds to concentration changes
by switching ranges for optimum readout sensitivity. If the current range
limits are exceeded, the instrument will automatically shift to the next higher
range. If the concentration falls to below 85% of full scale of the next lower
range, the instrument will switch to that range. A corresponding shift in the
DC percent-of-range output, and in the range ID outputs, will be noticed.

The autoranging feature can be overridden so that analog output stays
on a fixed range regardless of the oxygen concentration detected. If the
concentration exceeds the upper limit of the range, the DC output will
saturate at 1 V dc (20 mA at the current output).

However, the digital readout and the RS-232 output of the concentra­tion are unaffected by the fixed range. They continue to read accurately with
full precision. See Front Panel description in Chapter 1.

The automatic air calibration range is always 0-25 % and is not pro­grammable.

4.10.1 Setting the Analog Output Ranges

To set the ranges, ENTER the RANGE function mode by selecting
RANGE from the MAIN MENU. The RANGE screen appears.

L100 M1000

H10000 ModeAUTO

Use the DOWN/UP control to the range to be set: low (L), medium (M),
or high (H).

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Trace Oxygen Analyzer Operation 4

Use the DOWN/UP control to enter the upper value of the range (all

ranges begin at 0 ppm). Repeat for each range you want to set. ENTER to
accept the values and return to the Analysis Mode. (See note below.)

Note: The ranges must be increasing from low to high, for example,

if range 1 is set as 0–100 ppm and range 2 is set as 0–1,000
ppm, range 3 cannot be set as 0–500 ppm since it is lower than
range 2.

Ranges, alarms, and spans are always set in ppm units (over the entire
0-250,000 ppm range), even though all concentration-data outputs change
from ppm units to percent when the concentration is above 10,000 ppm.

After defining your analysis ranges, set Mode to either AUTO or one
of the fixed ranges, as described below.

4.10.2 Fixed Range Analysis

The autoranging mode of the instrument can be overridden, forcing the
analyzer DC outputs to stay in a single predetermined range.

To switch from autoranging to fixed range analysis, ENTER the
RANGE function by selecting RANGE from the MAIN MENU.

Use the DOWN/UP control to move AUTO between the arrows.

Use the DOWN/UP control to switch from AUTO to FX/LO, FX/MED,
or FX/HI to set the instrument on the desired fixed range (low, medium, or
high).

L100 M1000

H10000 ModeFX/LO

or

L100 M1000

H10000 ModeFX/MED

or

L100 M1000

H10000 ModeFX/HI

ESCAPE to re-enter the ANALYZE screen using the fixed range.

NOTE:When performing analysis on a fixed range, if the oxygen

concentration rises above the upper limit, as established by
the setup, for that particular range, the output saturates at 1
V dc (or 20 mA). However, the digital readout and the RS-232

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4 Operation Model 3020T

output continue to read the true value of the oxygen concen­tration regardless of the analog output range.

4.11 The CONTRAST Function

Contrast Function is

(Refer to Section 1.6)

If you cannot read anything on the display after first powering up:

1. Observe LED readout.

a. If LED meter reads all eights and dots, go to step 3.
b. If LED meter displays anything else, go to step 2.

2. Disconnect power to the Analyzer and reconnect again. LED
meter should now read all eights and dots.

DISABLED

4.12 The ST ANDBY Function

In STANDBY, the analyzer’s internal circuits are powered, but there

are no displays or outputs from the analyzer.

WARNING: THE POWER CABLE MUST BE UNPLUGGED TO

FULLY DISCONNECT POWER FROM THE INSTRU­MENT. WHEN THE ACCESS DOOR IS OPEN AND
THE POWER CABLE IS CONNECTED, EXTRA
CARE IS REQUIRED TO AVOID CONTACT WITH
LIVE ELECTRICAL CIRCUITS.

CAUTION: If you disconnect the primary power source from

the analyzer, then on re-energizing, you will be
required to choose to keep the configuration you
previously programmed into your instrument in the
Setup Mode, or it will reset to factory defaults.

Use this function whenever you want to power down without loosing

all of the configuration you programmed into your instrument in the Setup
Mode.

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Trace Oxygen Analyzer Operation 4

4.13 The

Analysis Mode

This is the normal operating mode of the analyzer. In this mode the
analyzer is monitoring the sample, measuring and displaying the amount of
oxygen, and reporting alarm conditions.

Normally, all of the functions automatically switch back to the Analysis
Mode ANALYZE screen when they have completed their assigned opera­tions. After four or five minutes in the MAIN MENU without any action by
the operator, the analyzer automatically switches itself back to the ANA­LYZE screen. ESCAPE, asserted one or more times, depending on the
starting point, also switches the analyzer back to the ANALYZE screen.

IMPORTANT:In the event of loss of flow through the analyzer, if the

vent is vented to a location of high oxygen content,
oxygen will back diffuse through the vent line and in
most cases quickly saturate the cell with oxygen which

can then require a quite long purge down time for the

sensor when then exposed to low oxygen concentra­tions. In the event that flow is to be interrupted into the
analyzer, it is suggested that the user do one of the
following:

1. Bag the sensor in nitrogen during this time

2. Install a shut off valve on the vent port of the ana­lyzer or somewhere within the users sample system.

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4 Operation Model 3020T

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Trace Oxygen Analyzer Maintenance 5

Maintenance

5.1 Routine Maintenance

Aside from normal cleaning and checking for leaks at the gas connec­tions, routine maintenance is limited to replacing Micro-Fuel cells and fuses,
and recalibration. For recalibration, see Section 4.4 The Zero and Span
Functions.

WARNING: SEE WARNINGS ON TITLE PAGE OF THIS MANUAL.

5.2 Major Internal Components

All internal components are accessed by unbolting and swinging open
the front cover, as described earlier. The major internal component locations
are shown in Figure 3-1, the cell block is illustrated in Figure 3-2, and the
fuse receptacle is shown in Figure 3-3

The 3020T contains the following major internal components:

• Micro-Fuel Cell (L-2C)

• Stainless steel cell block

• Customer Interface PCB (Power Supply on bottom surface)

• Preamp PCB (Contains Microprocessor)

• Front Panel PCB (Contains Displays)
5 digit LED meter
2 line, 20 character, alphanumeric, VFD display

• Solenoid Operated Gas Control Valves (–C option only).

See the drawings in the Drawings section in back of this manual

for details.

Teledyne Analytical Instruments

5-1

5 Maintenance Model 3020T

Figure 5-1: Major Internal Components

To swing open the cover panel, remove all screws.

5.3 Cell Replacement

The Micro-Fuel Cell is a sealed electrochemical transducer with no
electrolyte to change or electrodes to clean. When the cell reaches the end of
its useful life, it is replaced. The spent fuel cell should be discarded in accor­dance with to all applicable safety and environmental regulations. This
section describes fuel cell care as well as when and how to replace it.

The Class L-2C Micro-Fuel Cell is used in the standard Model 3020T.
If any other cell is supplied with your instrument, check the front of this
manual for any addenda applying to your special model.

5-2

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Trace Oxygen Analyzer Maintenance 5

5.3.1 Storing and Handling Replacement Cells

To have a replacement cell available when it is needed, it is recom­mended that one spare cell be purchased 9-10 months after commissioning
the 3020T, or shortly before the end of the cell's one year warranty period.

CAUTION: Do not stockpile cells. The warranty period starts on

the day of shipment.

The spare cell should be carefully stored in an area that is not subject to
large variations in ambient temperature (75 °F nominal) or to rough handling.

WARNING: THE SENSOR USED IN THE MODEL 3020T TRACE

OXYGEN ANALYZER USES ELECTROLYTES
WHICH CONTAIN TOXIC SUBSTANCES, MAINLY
LEAD AND POTASSIUM HYDROXIDE, THAT CAN
BE HARMFUL IF TOUCHED, SWALLOWED, OR
INHALED. AVOID CONTACT WITH ANY FLUID OR
POWDER IN OR AROUND THE UNIT. WHAT MAY
APPEAR TO BE PLAIN WATER COULD CONTAIN
ONE OF THESE TOXIC SUBSTANCES. IN CASE OF
EYE CONTACT, IMMEDIATELY FLUSH EYES WITH
WATER FOR AT LEAST 15 MINUTES. CALL PHYSI­CIAN. (SEE APPENDIX, MATERIAL SAFETY DATA
SHEET.)

CAUTION: Do not disturb the integrity of the cell package until

the cell is to actually be used. If the cell package is
punctured and air is permitted to enter, the cell will
require an excessively long time to reach zero after
installation (1-2 weeks!).

5.3.2 When to Replace a Cell

The characteristics of the Micro-Fuel Cell show an almost constant
output throughout its useful life and then fall off sharply towards zero at the
end. Cell failure in the 3020T is usually characterized inability to zero the
instrument down to a satisfactorily low ppm reading. When this occurs, the
3020T system alarm trips, and the screen displays a failure message.

#.# ppm Anlz

CELL FAIL/ ZERO HIGH

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5 Maintenance Model 3020T

Before replacing the cell:

a. Check your span gas to make sure it is within specifications.
b. Check for leaks downstream from the cell, where oxygen may be

leaking into the system.

If there are no leaks and the span gas is OK, replace the cell.

5.3.3 Removing the Micro-Fuel Cell

The Micro-Fuel Cell is located inside the stainless steel cell block

behind the front panel (see Figure 5-1). To remove an existing cell:

1. Remove power to the instrument by unplugging the power cord
at the power source.

2. Open the front panel door by unbolting it and swinging it open
on its hinges.

3. Leave the cell block installed. Place one hand underneath the cell
block, ready to catch the cell holder and Micro-Fuel Cell.

4. Lift up on the stainless steel gate in front of the cell block. This
releases the cell and cell holder from the block. The cell and
holder will fall out in your hand.

5-4

Teledyne Analytical Instruments

Trace Oxygen Analyzer Maintenance 5

Lift Up

Gate

Figure 5-2: Exploded View of Cell Block and Micro-Fuel Cell

Teledyne Analytical Instruments

5-5

5 Maintenance Model 3020T

5.3.4 Installing a New Micro-Fuel Cell

It is important to minimize the amount of time that a Teledyne Trace
Oxygen Sensor is exposed to air during the installation process. The quicker the
sensor can be installed into the unit, the faster your TAI O2 sensor will recover
to low O2 measurement. levels.

CAUTION: Do not touch the sensing surface of the cell. It is cov-

ered with a delicate Teflon membrane that can leak
when punctured. The sensor must be replaced if the
membrane is damaged.

Before installing a new cell, check the O-ring in the base of the cell holder.
Replace if worn or damaged.

Place the cell on the holder with the screen side facing down.

Note: There is a small location hole drilled in the holder. This hole

mates with a guide pin on the bottom rear of the cell block. The
hole in the cell block holder must align with the guide pin on the
cell block.

Step 1. Remove power from instrument.
Step 2. Remove the old sensor (if installed) from the analyzer.
Step 3. Purge the analyzer at approximately 1 SCFH flow rate with

N2 (or applicable sample gas with the sensor holder re-

moved).
Step 4. Remove sensor from double bag storage.
Step 5. Remove sensor shorting button.
Step 6. Place sensor on sensor holder so that the gold contact plate of

the sensor is facing up towards the sky.
Step 7. Install sensor and sensor holder into cell block.

Step 8. With O-ring in place, align the guide pin with the hole on the

cell holder. Then, with the holder, lift cell into the cell block.
Step 9. Push the gate on the cell block down so that the slots on the

side of the gate engage the locating screws on the side of the

block. This forces the holder into position and forms a gas-

tight seal.
Step 10. Purge system with sample or zero gas.
Step 11. Power-up.

If steps 4 through 10 are accomplished quickly (elapsed time less
than 15 seconds), recovery to less than 1ppm level should occur in
less than 8 hours.

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Teledyne Analytical Instruments

Trace Oxygen Analyzer Maintenance 5

5.3.5 Cell Warranty

The Class L-2C Micro-Fuel cell is used in the Model 3020T. This cell
is a long life cell and is warranted for 1 year from the date of shipment. If
any other cell is supplied with your instrument, check the front of this
manual for any special information applying to your cell.

With regard to spare cells, warranty period begins on the date of ship­ment. The customer should purchase only one spare cell (per section 5.3.1).
Do not attempt to stockpile spare cells.

The L-2C cell is not designed for applications where CO2 is a
major component in the sample, however concentrations of 1,000 ppm or

less will not adversely effect the cell performance. Consult Analytic Instru­ments for available options for either intermittent or continuous CO2 expo­sure.

If a cell was working satisfactorily, but ceases to function before the
warranty period expires, the customer will receive credit toward the purchase
of a new cell.

If you have a warranty claim, you must return the cell in question to the
factory for evaluation. If it is determined that failure is due to faulty work-

manship or material, the cell will be replaced at no cost to you.

Note: Evidence of damage due to tampering or mishandling will

render the cell warranty null and void.

5.4 Fuse Replacement

The 3020T requires two 5 x 20 mm, 4 A, T type (Slow Blow) fuses.
The fuses are located inside the explosion proof housing on the Electrical
Connector Panel, as shown in Figure 5-2. To replace a fuse:

1. Disconnect the Unit from its power source.

2. Place a small screwdriver in the notch in the fuse holder cap,
push in, and rotate 1/4 turn. The cap will pop out a few
millimeters. Pull out the fuse holder cap and fuse, as shown in
Figure 5-3.

Teledyne Analytical Instruments

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5 Maintenance Model 3020T

Figure 5-3: Removing Fuse Cap and Fuse from Holder

2. Replace fuse by reversing process in step 1.

5.5 System Self Diagnostic Test

Use the DOWN/UP control to scroll through the MAIN MENU to

SELF-TEST. The screen will follow the running of the diagnostic.

RUNNING DIAGNOSTIC

Testing Preamp  83

During preamp testing there is a countdown in the lower right corner of

the screen. When the testing is complete, the results are displayed.

Power: OK Analog: OK

Preamp: 3

The module is functioning properly if it is followed by OK. A number
indicates a problem in a specific area of the instrument. Refer to Table 5-1
for number-code information. The results screen alternates for a time with:

Press Any Key

To Continue...

The following failure codes apply:

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Teledyne Analytical Instruments

Trace Oxygen Analyzer Maintenance 5

Table 5-1: Self Test Failure Codes

Power

0OK
1 5 V Failure
2 15 V Failure
3 Both Failed

Analog

0OK
1 DAC A (0–1 V Concentration)
2 DAC B (0–1 V Range ID)
3 Both Failed

Preamp

0OK
1 Zero too high
2 Amplifier output doesn't match test input
3 Both Failed

Teledyne Analytical Instruments

5-9

5 Maintenance Model 3020T

5-10

Teledyne Analytical Instruments

Trace Oxygen Analyzer Appendix

Appendix

A-1 Specifications

Packaging: Explosion-proof. Bulkhead mount.

Sensor: L-2C trace analysis Micro-Fuel Cell.

Cell Block: 316 stainless steel.

Ranges: Three user definable ranges from 0–10 ppm to

0–250,000 ppm, plus air calibration range of 0­250,000 ppm (25 %).

Autoranging with range ID output.

Sample System: Flow indicator visible from front of unit.

Positive pressure service.
Vacuum service (optional).
Auto Cal / Auto Zero. (Available with op-

tional, electrically operated valves.)

Alarms: One system-failure alarm contact to detect

power failure.
Two adjustable concentration threshold alarms

with fully programmable setpoints.

Diagnostics: Start-up or on-demand, comprehensive, self

testing function initiated by keyboard or
remote command.

Displays: 2 line by 20 alphanumeric, VFD screen, and

one 5 digit LED display.

Digital Interface: Full duplex RS-232 communications port.

Power: Universal power supply 115 or 230 V ac, at

50 or 60 Hz.

Teledyne Analytical Instruments

A-1

Appendix Model 3020T

Operating Temperature: 0-50 °C

Accuracy: ±2% of full scale at constant

temperature.
±5% of full scale over operating temperature
range, on factory default analysis ranges, once
thermal equilibrium has been achieved.

Analog outputs: 0-1 V dc percent-of-range

0-1 V dc range ID.
4-20 mA dc percent-of-range
4-20 mA dc range ID.

Password Access: Can be user-configured for password

protection.

A-2

Teledyne Analytical Instruments

Trace Oxygen Analyzer Appendix

A-2 Recommended 2-Year Spare Parts List

Qty Part Number Description

1 C62371B Display PCB
1 D65295A Customer Interface PCB
1 C62368-A Trace Preamplifier Board
1 C62365-A Main PCB
3 F1295 Fuse, 4A, 250V, 5x20 mm, T (Slow

Blow)

1 O165 O-ring
1 C6689-L2C Micro-Fuel Cell

A minimum charge is applicable to spare parts orders.

Note: Orders for replacement parts should include the part number

(if available) and the model and serial number of the instru­ment for which the parts are intended.

Orders should be sent to:

Teledyne Analytical Instruments
16830 Chestnut Street
City of Industry, CA 91749-1580

Phone [phone], Fax [phone]
TWX [phone] TDYANYL COID

Web: www.teledyne-ai.com
or your local representative.

Teledyne Analytical Instruments

A-3

Appendix Model 3020T

A-3 Drawing List

D65908 Final Assembly Drawing
D65909 Outline Drawing
D65911 Wiring Diagram

A-4

Teledyne Analytical Instruments

Trace Oxygen Analyzer Appendix

A-4

3000 SERIES ANALYZERS

APPLICATION NOTES ON RESTRICTORS,

PRESSURES, AND FLOW RECOMMENDATIONS

3000 series analyzers require reasonably regulated sample pressures.
While the 3000 analyzers are not sensitive to variations of incoming pressure
(provided they are properly vented to atmospheric pressure) the pressure must
be maintained as to provide a useable flow rate trough the analyzer. Any line
attached to sample vent should be 1/4 or larger in diameter.

FLOW RATE RECOMMENDATIONS:

A usable flow rate for a 3000 series analyzer is one which can be
measured on the flowmeter. This is basically .2 - 2.4 SLPM . The optimum flow
rate is 1 SLPM (mid scale). Note: response time is dependent on flow rate, a
low flow rate will result in slow response to O2 changes in the sample stream.
The span flow rate should be the approximately same as the sample flow rate.

CELL PRESSURE CONCERNS:

The sensors used in 3000 series analyzers are optimized to function at
atmospheric pressure. At pressures other than atmospheric the diffusion rate of
O2 will be different than optimum value. Higher pressures will produce faster O2
diffusion rates resulting in higher O2 reading and shorter cell life. To use a 3000
series analyzer at a cell pressure other than atmospheric, the analyzer must be
calibrated with a known calibration gas at the new cell pressure to adjust for the
different diffusion rate. Cell pressures below 2/3 atmospheric are not recom­mended because as they tend to cause excessive internal expansion which may
result in seal failure.

For operation at cell pressures other than atmospheric care must be
taken not to change the sample pressure rapidly or cell damage may occur. For
cell pressures above atmospheric, caution must be exercised to avoid over
pressuring the cell holder. ( percent analyzers will require some type of cell
retainer to prevent the cell from being pushed out by the pressure .) For opera­tion at pressures below atmospheric pressure a suffix C ( clamped) cell is
required.

RESTRICTION DEVICES:

For proper operation, all 3000 series analyzers require a flow restriction
device. This device is typically a restrictor or a valve. This restriction device
serves two functions in the sample path. The first function is to limit the flow rate
of the sample through the analyzer. A restrictor is chosen to operate over a range
of pressures and provide a useable flow rate over that range.

Teledyne Analytical Instruments

A-5

Appendix Model 3020T

The second function that the restriction device provides is a pressure
drop. This device is selected to provide the only significant pressure drop in the
sample path.

RESTRICTOR KIT

The current revision of the 3000 series analyzers are supplied with a kit
containing two restrictors and a union which are user installed. These parts
supplied to give the end user more flexibility when installing the analyzer. The
restrictor kit is suitable for high and low positive pressure applications as well as
vacuum service ( atmospheric pressure sample) applications ( see manual for
installation instructions). The standard restrictor ( BLUE DOT ) is recommended
for pressures between 5 PSIG and 50 PSIG. For positive low pressure appli­cation ( 5 psig or less ) the un-marked restrictor is better suited . For none
pressurized sample applications the marked restrictor should be used and
configured for vacuum service. Note: for extremely low positive pressure appli­cations ( less then 2 psig) the vacuum service configuration should provide higher
performance ( higher flow rates). For vacuum service the end user must supply
a vacuum pump and a by-pass valve for the pump. A vacuum level of 5 -10
inches of mercury should provide the optimum flow rate. CAUTION: flow

restrictors have very small orifices and may be plugged by small par­ticles ( .005” dia or larger) A sample filter must be included in the sample
line prior to the restrictor! ( a 60 micron filter is recommended)

3020T EXAMPLES:

Example 1, with a incoming pressure of 10 psig the std restrictor (blue
dot) will provide a flow rate of .76 SLPM. Up-stream of the restrictor the
sample line pressure will be 10 psig, while down stream ( including the cell) the
pressure will be at atmospheric pressure.( analyzer vented to atmospheric
pressure) Note, all other pressure drops in the sample path are insignificant at
these flow rates. This insures that the cell operates at atmospheric pressure. At
very high flow rates ( off scale of flow-meter), pressure drops other than the
restriction device could become significant , and result in pressurizing the cell.

Example 2, A 3020T is configured for vacuum service as follows. The
un-marked restrictor is placed in the sample vent port. The down stream end of
the restrictor is then connected to a vacuum pump and by-pass valve. The by­pass valve is adjusted to provide a flow rate of 1 SLPM. The sample pressure
between the pump and the restrictor will be approximately -7 inches of mercury,
while the pressure in the balance of the sample system including the cell will be
approximately at atmospheric pressure. ( provided the sample flow into the
analyzer is not blocked.)

A-6

Teledyne Analytical Instruments

Trace Oxygen Analyzer Appendix

BY-PASS:

To improve the system response, a by-pass can be added to increase the sample flow
rate to the analyzer by a factor of ten. A by-pass provides a sample flow path around the
analyzer of 2 - 18 SCFH. typically.

CALIBRATION GAS:

3000 series analyzer requirements for units with Auto-Cal options. The customer must

supply a control valves (or restrictors) for any SPAN or ZERO gas source which is attached
to the Auto-Cal ports. The valve should be adjusted to the same flow rate as the sample gas .
When restrictors are used, the gas pressure must be adjusted to achieve the proper flow rate.

OPERATION WITHOUT A RESTRICTOR DEVICE:

Operation without a restrictor device is not recommend as mentioned above. A
3020T without any flow restrictor device was tested on 11-19-97. This results in a flow rate
of 2.4 SLPM @ 1 PSIG. This is a cv of 0.023 for the standard sample sys.

REFERENCE: FLOW_1.XLS & FLOW_2.XLS for information on flow rates at

various pressures.

TAI PART NUMBERS

RESTRICTOR KIT: A68729
UNION (SS) U11
LP. RESTRICTOR R2323 ( LOW PRESSURE / VAC. SERVICE )
STD.. RESTRICTOR R2324 BLUE DOT
NUT N73
FERRULE F73
FERRULE F74 BOTH FERRULES ARE

REQUIRED

CONVERSIONS:

1 PSI = 2.04 INCHES OF MERCURY (in. Hg.)
1 SCFH = 0.476 SLPM

Teledyne Analytical Instruments

A-7