Teledyne 3000TB-XL User Manual
Trace Oxygen Analyzer
OPERATING INSTRUCTIONS FOR
Model 3000TBXL
Trace Oxygen Analyzer
D ANGER
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 PERSIST
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 M3000TBXL
12/04/2013
i
Model 3000TBXL
Copyright © 2013 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 91748.
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
Model 3000TBXL complies with all of the requirements of the
Commonwealth of Europe (CE) for Radio Frequency Interference,
Electromagnetic Interference (RFI/EMI), and Low Voltage Directive
(LVD).
The following International Symbols are used throughout the Instruction Manual for your visual and immediate warnings and when
you have to attend CAUTION while operating the instrument:
STAND-BY, Instrument is on Stand-by,
but circuit is active
GROUND
Protective Earth
CAUTION, The operator needs to refer to the manual
for further information. Failure to do so may
compromise the safe operation of the equipment.
CAUTION, Risk of Electric Shock
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iii
Model 3000TBXL
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 Displays................................................................. 1-6
1.5.2 Function Keys ........................................................ 1-6
1.5.3 Data Entry Keys ..................................................... 1-6
1.5.4 I/O P ower Button.................................................... 1-7
1.5.5 Access Door .......................................................... 1-7
1.6 Recognizing Difference Between LCD & VFD............... 1-7
1.7 Equipment Interface ....................................................... 1-7
1.7.1 Electrical Connector Panel .................................... 1-7
1.7.2 Gas Connector Panel............................................. 1-9
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
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 Power............................................... 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 DI 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
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Trace Oxygen Analyzer
3.4 Installing the Micro-Fuel Cell ........................................ 3-12
3.5 Gas Connections ...........................................................3-12
3.6 Testing the System.........................................................3-14
4 Operation
4.1 Introduction .................................................................... 4-1
4.2 Using the Data Entry and Function Buttons ................... 4-2
4.3 The System Function ..................................................... 4-3
4.3.1 Tracking the O
Readings during Calibration ......... 4-4
2
4.3.2 Setting up an Auto-Cal........................................... 4-5
4.3.3 Pass w ord Protection.............................................. 4-6
4.3.3.1 Entering the Password................................... 4-6
4.3.3.2 Installing or Changing the Password ............. 4-7
4.3.4 Logout.................................................................... 4-9
4.3.5 System Self-Diagnostic Test ..................................4-9
4.3.6 Version Screen ...................................................... 4-10
4.3.7 Showing Negative Oxygen readings ..................... 4-10
4.4 The Zero and Span Functions ....................................... 4-11
4.4.1 Zero Cal ................................................................. 4-12
4.4.1.1 Auto Mode Zeroing ........................................ 4-12
4.4.1.2 Manual Mode Zeroing.................................... 4-13
4.4.1.3 Cell Failure .................................................... 4-13
4.4.2 Span Cal................................................................ 4-14
4.4.2.1 Auto Mode Spanning ..................................... 4-14
4.4.2.2 Manual Mode Spanning................................. 4-15
4.4.3 Span Failure ........................................................ 4-16
4.5 The Alarms Function...................................................... 4-16
4.6 The Range Function ...................................................... 4-19
4.6.1 Setting the Analog Output Ranges....................... 4-19
4.6.2 Fixed Range Analysis .......................................... 4-20
4.7 The Analyze Function .................................................... 4-21
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
5.3.4 Installing a New Micro-Fuel Cell.............................. 5-6
5.3.5 Cell
Lifetime ........................................................... 5-7
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Model 3000TBXL
5.4 Fuse Replacement ......................................................... 5-7
5.5 System Self Diagnostic Test........................................... 5-
5.6 Troubleshooting ............................................................. 5-9
Appendix
A-1 Specifications ................................................................ A-1
A-2 Recommended 2-Year Spare Parts List ......................... A-2
A-3 Drawing List................................................................... A-3
A-5 Application Notes on Restrictors, Pressure & Flow........ A-4
8
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Trace Oxygen Analyzer
DANGER
COMBUSTIBLE GAS USAGE WARNING
This is a general purpose instrument designed for usage in a
nonhazardous area. It is the customer's responsibility to ensure safety especially when combustible gases are being analyzed since the potential of gas leaks always exist.
The customer should ensure that the principles of operating of
this equipment is well understood by the user. Misuse of this
product in any manner, tampering with its components, or
unauthorized substitution of any component may adversely
affect the safety of this instrument.
Since the use of this instrument is beyond the contr ol of
Teledyne , no responsibility by Teledyne , its affiliates, and
agents for damage or injury from misuse or neglect of this
equipment is implied or assumed.
Teledyne Analytical Instruments
vii
Model 3000TBXL
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 is supplied are indicated by a
check mark in the box.
Instrument Serial Number:
_______________________
Options Available for the Instrument with the Above Serial Number:
Sensor Options Available for the Instrument with the Above Serial Number:
Auto Calibration Valves:
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.
B-2CXL (P/N C6689-B2CXL) Default sensor
A-2CXL (P/N B74033-A2CXL)
B-2CXL Insta-Trace (P/N B73592)
A-2CXL Insta-Trace (P/N B77856)
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Trace Oxygen Analyzer Introduction 1
Introduction
1.1 Overview
The Teledyne Analytical Instruments Model 3000TBXL Trace Oxygen
Analyzer is a versatile microprocessor-based instrument for detecting oxygen
in a variety of gases. This manual covers the Model 3000TB
bulkhead-mount, general purpose units only. These instruments are for use in
nohazardous environments only.
XL, trace oxygen,
1.2 Typical Applications
A few typical applications of the Model 3000TBXL 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 3000TBXL 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 250,000 ppm. Large, bright, meter readout.
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1 Introduction Model 3000TBXL
• 316 Stainless steel cell block and sample system—all wetted
parts.
• Advanced Micro-Fuel Cell for trace analysis. Standard Insta Trace cell
has rapid recovery from air to low ppm during initial installation.
• 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 0-1 ppm through 025 % 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.
• Analog outputs for concentration and range identification.
(0-1 V dc standard, and isolated 4–20 mA dc optional.)
1.4 Model Designations
3000TBXL: Standard model.
3000TBXL-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 3000TBXL electronics, to automatically switch between
gases in synchronization with the analyzer’s operations.
1-2
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Trace Oxygen Analyzer Introduction 1
1.5 Operator Interface
Figure 1-1 is an illustration of the front of the Model 3000TBXL Oxygen
Analyzer with the outer door open showing the control panel (which is also
the inner door).
All displays on the standard 3000TB
housing. The instrument has a digital meter and an alphanumeric display,
which are viewed through a glass viewing window in the front door of the
main housing, and a sample flowmeter on the gas control panel attached to
the main housing. They give the operator constant feedback from the instrument.
The operator controls are pushbutton membrane switches located
behind the front door of the main housing. All of them are reached by
swinging open the outer door of the enclosure. They are described briefly
here and in greater detail in chapter 4.
Figure 1-2 shows the 3000TB
open. The inner door is opened for access to the electrical connections and to
the cell block which houses the Micro-Fuel Cell. Door mounted components
are shown in chapter 5.
XL with the outer door and inner door both
XL are visible from outside the
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1 Introduction Model 3000TBXL
(Pressing the latch button
will open the Inner Door)
Figure 1-1: Model 3000TBXL—Outer Door Open—Showing Control Panel
1-4
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Trace Oxygen Analyzer Introduction 1
Figure 1-2: Model 3000TBXL—Inner Door Open—Showing Internal Components
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1 Introduction Model 3000TBXL
1.5.1 Displays
Digital Meter Display: The meter display is a LED device that
produces large, bright, 7-segment numbers that are legible in any lighting
environment. It produces a continuous readout from 0-9999 ppm and from 125 %. It is accurate across all ranges without the discontinuity of analog
range switching.
Alphanumeric Interface Screen: The backlit 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).
1.5.2 Function Keys
Six touch-sensitive membrane switches are used to change the specific
function performed by the analyzer:
• Analyze Perform analysis for oxygen content of a sample gas.
• System Perform system-related tasks (described in detail in
chapter 4, Operation.).
• 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.
1.5.3 Data Entry Keys
Six touch-sensitive membrane switches are used to input data and
commands to the instrument via the alphanumeric VFD display:
• Left & Right Arrows Select between functions currently
displayed on the VFD screen.
• Up & Down Arrows Increment or decrement values of
functions currently displayed.
1-6
• Enter Moves VFD display on to the next screen in a series. If
none remains, returns to the Analyze screen.
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Trace Oxygen Analyzer Introduction 1
• Escape Moves VFD display back to the previous screen in a
series. If none remains, returns to the Analyze screen.
1.5.4 I/O Power Button
The red I/O button switches the instrument power between I (ON) and
O (a Keep-Alive state). In the O state, the instrument’s circuitry is operating,
but there are no displays or outputs.
CAUTION: The power cable must be unplugged to fully
disconnect power from the instrument. When
chassis is exposed or when access door is open
and power cable is connected, use extra care to
avoid contact with live electrical circuits.
1.5.5 Access Door
To access the electrical connector panel, or the cell block, the control
panel doubles as an inner door that can be unlatched and swung open (after
unlatching and swinging open the outer access door). See Figure 1-2.
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 1-3, contains the
electrical connections for external inputs and outputs. 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.
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1 Introduction Model 3000TBXL
3.0 A MAX
Figure 1-3: Electrical Connector Panel
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.
• Alarm Connections 2 concentration alarms and 1 system
alarm.
1-8
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Trace Oxygen Analyzer Introduction 1
• RS-232 Port Serial digital concentration signal output
and control input.
• Remote Valves Used for controlling external solenoid
valves, if desired.
• 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 1-4, 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.
Note:
For Additional information,
please, see page 1-4
Figure 1-4: Model 3000TBXL Gas Connector Panel
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1 Introduction Model 3000TBXL
• Gas Inlet and Outlet One inlet (must be externally valved)
and one exhaust out.
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 3000TB electronics.
Note: If you require highly accurate Auto-Cal timing, use external
Auto-Cal control where possible. The internal clock in the
Model 3000TB
scheduled calibrations can vary 2-3 % per day.
XL is accurate to 2-3 %. Accordingly, internally
1-10
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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 3000TB
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.
XL unit is a Micro-Fuel
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 3000TBXL
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:
O
+ 2H2O + 4e– → 4OH
2
–
(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 3000TBXL
In addition, since there is zero output in the absence of oxygen, the
characteristic curve has close to an absolute zero (less than ± 0.2ppm
oxygen). This means there is usually no need to zero calibrate the
instrument. Depending upon the application, zeroing may still be used to
compensate for the combined zero offsets of the cell and the electronics
.
As long as the unit has not been contaminated by a liquid, the default
zero of this instrument will be stable (± 100 ppb or less) in excess of 10
years.
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.
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 3000TB
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 can be used if needed. The sample or
calibration gas flowing through the system is monitored by a flowmeter
downstream from the cell.
XL sample system is designed and fabricated to ensure
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2 Operational Theory Model 3000TBXL
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 option is
ordered. The valves, when supplied, are installed inside the 3000TB
sure and are regulated by the instruments internal electronics.
XL enclo-
Span In
Zero In
Sample In
In vacuum service the
restrictor sh ou ld b e
placed here.
Solenoid
Valves
In norma l service the
restrictor sh ou ld b e
placed here.
Com ponents in the shaded area are in
the -C option (internal control valves)
only and are not shown in the piping
diagram above.
Cell
Flowmeter
Exhaust Out
Restrictor
Figure 2-4: Flow Diagram
2.4 Electronics and Signal Processing
The signal processing and display electronics PCBs are mounted on the
back of the inner door. See Major Internal Components in chapter 5, for
illustration. The power supply module is mounted underneath the bottom end
of the Electrical Connector Panel.
The Model 3000TB
XL 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. CE approved units for the European
market also contain an EMI filter. Figure 2-5 is a simplified block diagram of
the Analyzer electronics.
2-6
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