Teledyne 3020M User Manual
Percent Paramagnetic Oxygen Analyzer
OPERATING INSTRUCTIONS FOR
Model 3020M
Percent Paramagnetic
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 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 M69993
12/18/98
ECO:#98-0569
i
Model 3020M
Copyright © 1998 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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Teledyne Analytical Instruments
Percent Paramagnetic 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 is supplied are indicated by a check mark in the
box.
Instrument Serial Number: _______________________
Options Included in the Instrument with the Above Serial Number:
❑❑
❑
3020M-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 3020M electronics, to automatically switch between
gases in synchronization with the analyzer’s operations
❑❑
❑
3020M-F: Includes flame arrestors for Group C and D service.
❑❑
❑❑
❑
3020M-G: Includes flame arrestors for Groups C and D service, plus
❑❑
gas control valves as in –C option, above
❑❑
❑
3020M-H: Includes flame arrestors for Group B (hydrogen) service.
❑❑
❑❑
❑
3020M-I: Includes flame arrestors for Group B (hydrogen) service,
❑❑
plus gas control valves as in –C option, above.
❑❑
❑
3020M-M: 4-20 mA dc Signal and Range ID outputs (in addition to
❑❑
the standard dc voltage outputs.
Teledyne Analytical Instruments
iii
Model 3020M
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 .......................................................... 1-2
1.5.1 UP/DOWN Switch.................................................. 1-4
1.5.2 ESCAPE/ENTER Switch ....................................... 1-4
1.5.3 Displays ................................................................. 1-5
1.6 Recognazing Difference Between LCD & VFD .............. 1-5
1.7 Rear Panel (Equipment Interf ace).................................. 1-5
1.7.1 Electr ical 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 Paramagnetic Sensor..................................................... 2-1
2.2.1 Principles of Operation ............................................ 2-1
2.3 Cross Interference.......................................................... 2-3
2.4 Sample System.............................................................. 2-5
2.5 Electronics and Signal Processing ................................ 2-6
2.6 Temperature Control ...................................................... 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 Pow er............................................... 3-4
3.3.2 Fuse Installation..................................................... 3-4
3.3.3 Analog Outputs ...................................................... 3-4
3.3.4 Alarm Relays ......................................................... 3-7
3.3.5 Digital Remote Cal Inputs ...................................... 3-8
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 ....................3-11
3.4 Gas Connections .......................................................... 3-12
3.5 Testing the System........................................................ 3-13
iv
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer
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 SPAN Functions ..................................................... 4-9
4.8.1 Span Cal................................................................ 4-10
4.8.1.1 Auto Mode Spanning ..................................... 4-10
4.8.1.2 Manual Mode Spanning................................. 4-11
4.9 The CAL Function.......................................................... 4-11
4.10 The ALARMS Function.................................................. 4-13
4.11 The RANGE Function.................................................... 4-15
4.11.1 Setting the Analog Output Ranges......................... 4-16
4.11.2 Automatic Ranging ................................................ 4-16
4.11.3 Fixed Range Analysis ............................................ 4-16
4.12 The CONTRAST Function............................................. 4-17
4.13 The STANDBY Function................................................ 4-17
4.14 The
4.15 The
Analysis Mode ........................................................
Sensor Function .....................................................
4-18
4-18
Maintenance
5.1 Routine Maintenance..................................................... 5-1
5.2 Major Internal Components............................................ 5-1
5.3 Sensor Replacement ..................................................... 5-2
5.4 Fuse Replacement ......................................................... 5-2
5.5 System Self Diagnostic Test........................................... 5-3
5.6 Output Goes Negative.................................................... 5-4
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v
Model 3020M
Appendix
A-1 Specifications ................................................................ A-1
A-2 Recommended 2-Year Spare Parts List ......................... A-3
A-3 Drawing List................................................................... A-4
vi
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Introduction 1
Introduction
1.1 Overview
The Teledyne Analytical Instruments Model 3020M Percent Paramagnetic Oxygen Analyzer is a versatile microprocessor-based instrument for
detecting oxygen in a variety of gases. This manual covers the Model
3020M, percent oxygen, explosion-proof, bulkhead-mount units only.
1.2 Typical Applications
A few typical applications of the Model 3020M 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 3020M Percent 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 %
levels through 100%. Large, bright, meter readout.
• Stainless steel sample system.
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1-1
1 Introduction Model 3020M
• 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 0-5 % through 0-100
%) allow best match to users process and equipment.
• 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 VDC standard, and isolated 4–20 mADC)
1.4 Model Designations
3020M: Standard model.
3020M-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 3020M electronics, to automatically switch between gases
in synchronization with the analyzer’s operations
3020M-F: Includes flame arrestors for Groups C and D.
3020M-G: Includes flame arrestors for Groups C and D, & -C option.
3020M-H: Includes flame arrestors for Group B (Hydrogen service).
3020M-I: Includes flame arrestors for Group B, & -C option.
n.
1.5 Operator Interface
All controls and displays on the standard 3020M are accessible from
outside the housing. The instrument has two simple operator controls. The
operator has constant feedback from the instrument through an alphanumeric
display, a digital oxygen meter, and a sample flow meter. The displays and
1-2
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Introduction 1
controls are described briefly here and in greater detail in chapter 4. See
Figure 1-1.
Through Side Port
DIGITAL METER
VFD SCREEN
Through Side Port
Through Side Port
DOWN/UP
Through Side Port
SCCM
CONTROL
ESCAPE/ENTER
CONTROL
Figure 1-1: Model 3020M Controls, Indicators, and Connectors
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1-3
1 Introduction Model 3020M
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
twelve 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 Adjust LCD contrast.
• Standby Leave analyzer powered, but no outputs or displays.
Contrast Function is
(Refer to Section 1.6)
DISABLED
WARNING: THE POWER CABLE MUST BE DISCONNECTED TO
FULLY REMOVE POWER FROM THE INSTRUMENT.
CAUTION: VOLTAGE MAY BE PRESENT ON ALARM CON-
TACTS WHEN LINE POWER IS DISCONNECTED.
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.
With subfunction selected, moves VFD back through
items on screen, to first item, then moves VFD to
previous display.
1-4
• Enter With a Subfunction Selected: Moves VFD on to the
next screen in a series. If none remains, returns to the
Analyze
Teledyne Analytical Instruments
screen.
Percent Paramagnetic Oxygen Analyzer Introduction 1
With a Value Selected: Enters the value into the
analyzer as data. Advances VFD to next operation.
(See Chapter 4 for details.)
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 0-100 %. It is accurate across all
analysis ranges without the discontinuity inherent in 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 100 to
1000 standard cc per minute (cc/min x 100) valid for air or nitrogen.
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.
CAUTION: VOLTAGE MAY BE PRESENT ON ALARM CON-
TACTS WHEN LINE POWER IS DISCONNECTED.
Teledyne Analytical Instruments
1-5
1 Introduction Model 3020M
100-240 V
50/60Hz
3.0A Max.
1-6
Figure 1-2: Electrical Connector Panel
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Introduction 1
Electrical Connections: The electrical connections on the electrical
connector panel are described briefly here, and in more detail in chapter 3
Installation.
• Power Connection 100-240 VAC, 50 or 60 Hz.
• Analog Outputs 0-1 VDC concentration plus 0-1 V dc
range ID. Additional, isolated 4-20 mA
DC plus 4-20 mADC range ID
available.
• 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.
• 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.
Teledyne Analytical Instruments
1-7
1 Introduction Model 3020M
SCCM
Figure 1-3: Model 3020M Gas Connector Panel
• Gas Sample Inlet and Outlet One inlet 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 3020M electronics.
Note: If you require highly accurate Auto-Cal timing, use external
Auto-Cal control where possible. The internal clock in the
Model 3020M is accurate to 2-3 %. Accordingly, internally
scheduled calibrations can vary 2-3 % per day.
1-8
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Operational Theory 2
Operational Theory
2.1 Introduction
The analyzer is composed of three subsystems:
1. Paramagnetic 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 Paramagnetic Sensor is an electromechanical device that
translates the amount of oxygen present in the sample into an electrical
signal. 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 Precise Paramagnetic Sensor
2.2.1 Principles of Operation
The heart of the 3020M is a paramagnetic type oxygen sensor that is
maintanance free and has a long lifetime. Oxygen has a very high magnetic
sucseptibility compared to other gases and thus displays a particularly paramagnetic behaviour. A small glass dumbbell filled with nitrogen and rotating on a taut platinum wire is suspended in an inhomogneous magnetic field.
This glass dumbbell is diamagnetic and tends to rotate out of the magnetic
field. The strength of the resulting torque determined by an susceptibility of
the sample gas. This torque is compensated for by a counter torque induced
by an electrically charged platinum coil on the dumbbell. The zero position
of the dumbbell is controlled by means of an optical system consisting of a
light source, a mirror at the dumbbell axis and a pair of detectors. The
difference between the compensating currents required to bring the dumb-
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2-1
2 Operational Theory Model 3020M
bell to the zero position in the presence of zero gas (i.e. no O2 present) or of
sample gas is proportional to the partial pressure of oxygen in the sample
gas.
The sensor enclosure is temperature controlled to 55 degrees centigrade
to insure that the magnetic susceptibility of oxygen in the sample is not
affected by the ambient temperature. The measuring cell has a measuring
volume of approximately 3 cm
3
Sensor
(side view shown)
The Paramagnetic sensor enclosure holds not only the sensing elements,
but the temperature controller electronics, heating elements, sensor electronics, and preamplifier. The Electronics and heating elements require a separate
power source, from the rest of the 3020M capable of delivering 1.5 amps
approximately at 24 volts dc. The output of the sensor is roughly calibrated
to be 0 to 1 volt DC for the the range of 0 to 100 % 02. The true calibration
of the sensor is carried out by the microprocessor as described later in chapter 4. The electrical interconnections to the sensor are done through a 15 pin
D connector. Some signals from the sensor are not connected. They are only
useful for troubleshooting, by trained personnel, as test points.
2-2
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Operational Theory 2
Sensor
(rear view shown)
Pin out:
1 -15Vdc test pin (Not connected)
2 +15Vdc test pin (Not connected)
3 Measuring ground
4 Not used
5 Preamplifier output ~0- 1 Vdc
6 Not used
7 24 Vdc return, power ground
8 Collector of transistor switching heating element (Not con-
nected)
9 Fault signal: <0 Vdc= OK, >4.6 Vdc = Fault (Not connected)
10 Not used
11 Negative reference voltage (Not connected)
12 Positive reference voltage (Not connected)
13 Nominal temperature voltage signal (Not connected)
14 Actual temperature voltage signal (Not connected)
15 +24 Vdc power.
2. 3 Cross Interference
As mentioned previously, the selectivity of the measuring system is
based on the extraordinarily high magnetic susceptibility of Oxygen compared to other gases. In most cases the presence of other gases can be ignored but significant errors can occur when the sensor is calibrated with a
mixture of oxygen and nitrogen and the sample gas consists mainly of other
gases with considerable magnetic susceptibility. In this case, the reading
shows a measured value even if the sample gas contains no Oxygen. It is
actually displaying the cross sensitivity to another gas.
The following table shows the cross sensitivity of some gases when
changing from pure nitrogen to 100% of one of the gases listed.
Teledyne Analytical Instruments
2-3
2 Operational Theory Model 3020M
Gas Cross Gas Cross
Sensitivity Sensitivity
in vol. % in vol. %
Acetylene C2H
Allene C3H
4
Ammonia NH
2
3
-0.24 Hydrogen chloride HCI -0.30
-0.44 Hydrogen fluoride HF +0.10
-0.2 6 Hydrogen iodide HI -1.10
Argon Ar -0.22 Hydrogen sulphide H2S -0.39
Bromine Br
2
1.2 Butadiene C4H
1.3 Butadiene C4H
n-Butane C4H
10
6
6
-1.30 Iodine I -2.40
-0.49 Isobutane C4H
-0.49 Isopantane C5H
10
12
-1.11
-1.11 Krypton Kr -0.51
I-Butane C4H8 -085 Laughing gas N2O -0.20
cis 2-Butane C4H
trans 2-Butane C4H
Carbon dioxide CO
8
8
2
Carbon monoxide CO +0.06 Nitric acid HNO
Chlorine Cl
Cyclo hexane C6H
Ethane C2H
Ethylene C2H
2
12
6
4
Helium He +0.30 Propane C3H
n-Heptane C7H
n-Hexane C6H
Hydrogen H
16
14
2
-0.89 Methane CH
4
-0.20
-0.92 Neon Ne +0.13
-0.27 Neopentane C5H
12
3
-0.77 Nitrogen dioxide NO
2
-1.49
+0.43
+28.00
-1. 56 Nitrous oxide NO +40.00
-0.43 n-Octane C8H
-0.26 n-Pentane C5H
8
-2.10 Propylene C3H
18
12
6
-2.50
-1.45
-0.86
-0.55
-1. 70 Vinyl chloride -0.63
+0.24 Water H2O -0.02
Hydrogen bromide HBr -.0.61 Xenon Xe -0.95
-1.49
With gas mixtures the components are weighted according to their
proporational volumes.
The cross interference with a gas mixture can be determined in advance if the
concentration of the individual background gases is known.
Example:
Cross sensitivity calculation for a gas mixture:
The gas to be measured consists of 10 % CO2, 40 % of N2, and 50%
of Ar.
C02: -0.27 x 10% = -0.027
Ar: -0.22x5O%= -0.11
TOTAL CROSS INTERFERENCE -0.137
Calculation of the zero value:
2-4
Teledyne Analytical Instruments
Percent Paramagnetic Oxygen Analyzer Operational Theory 2
(0% 02) - (Cross Interference Value) = Zero Point Value
0%-(-0.137) = +0.137%0
2
2.4 Sample System
The sample system delivers gases to the sensor from the analyzer gas
panel inlets. Depending on the mode of operation either sample or calibration
gas is delivered.
The Model 3020M 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 low percent range 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 sensor.
The gases delivered to the instrument should be at constant pressures and
flow rates and must exit freely into the ambient atmosphere. The Span, Zero
and Sample gases should be delivered at constant pressures of about 10 psig
(Range 5-20). The flow rate must be maintained at about 700 cc/minute (Range
600-1000) and must exit freely into atmospheric pressure.
Supplied at
constant
pressure
of 10 psig
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 portions of the diagram show the components added when the –C and/or –F
options are ordered. The solenoid valves, when supplied, are installed inside the
3020M 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
Exhaust Out
into at hmospher e
Components in the shaded area are in
the -C option (internal control valves)
only and are not shown in the piping
diagram above.
Solenoid
Valves
Needle Valves
to adjust the flow
Figure 2-4: Flow Diagram
Sensor
Flowmeter
(Maintain at 700 cc/minute)
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2-5
2 Operational Theory Model 3020M
2.5 Electronics and Signal Processing
The Model 3020M Percent 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 Paramagnetic Sensor has its own dedicated universal 24V power supply that
feeds the sensors internal heater and electronics.
The signal processing electronics including the microprocessor, analog
to digital, and digital to analog converters are located on the main PCB, on
the front door (see figure 5-1). The preamplifier board is mounted on top of
the motherboard. These boards are accessible by opening the front door of
the explosion proof enclosure. Figure 2-5 is a block diagram of the Analyzer
electronics.
In the presence of oxygen the chamber is rotated in the magnetic field,
but the cell generates a current to countertorque the oxygen action. This
current is converted to a voltage, which is preamplified in the sensor internal
electronics.
The preamplified signal (0-1 Volt) is fed to the 3020M amplifier for
minor processing.
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.
2.6 Temperature Control
2-6
For accurate analysis the sensor temperature is controlled internally at
55OC.
Teledyne Analytical Instruments
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