Alpha Omega Instruments 2000 Operating Manual

SERIES 2000

PERCENT OXYGEN ANALYZER

Product shown with optional flow meter

Alpha Omega Instruments Corp.
40 Albion Road, Suite 100
Lincoln, RI 02865
Phone: [phone]
Fax: [phone]
Website: www.aoi-corp.com
Email: [e-mail]

Rev 3.0619.18, June 2018

COPYRIGHT ALPHA OMEGA INSTRUMENTS CORP.
ALL RIGHTS RESERVED INCLUDING THE RIGHT TO
REPRODUCE THIS MANUAL, OR ANY PORTION
THEREOF, IN ANY FORM.

ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

WARRANTY

Alpha Omega Instruments Corp. warrants the products delivered to be free from defects in material
and workmanship at the time of delivery to the Fob. point specified in the purchase order, its liability
under this warranty being limited to repairing or replacing, at Alpha Omega Instruments' option, items
which are returned to it prepaid within two years from the date of shipment and found to Seller’s
satisfaction to have been so defective.

Alpha Omega Instrument's two year sensor warranty offers protection for two (2) years from the date
of shipment of the Series 2000 Percent Oxygen Analyzer. Any sensor from a Series 2000 Percent
Oxygen Analyzer that fails under normal use must be returned to Seller prepaid and, if such sensor is
determined by Seller to be defective, Seller shall provide Buyer a replacement sensor. Buyer must
provide the serial number of the analyzer from which the sensor has been removed. If a sensor is
found to be defective and a new one issued, the warranty of the replacement sensor (s) is for a period
of two (2) years from the date of shipment. In no event shall Alpha Omega Instruments Corp. be liable
for consequential damages.

NO PRODUCT IS WARRANTED AS BEING FIT FOR A PARTICULAR
PURPOSE AND THERE IS NO WARRANTY OF MERCHANTABILITY.

This warranty applies only if:

(i) the items are used solely under the operating conditions and manner

recommended in this manual, specifications, or other literature;

(ii) the items have not been misused or abused in any manner or repairs

attempted thereon;

(iii) written notice of the failure within the warranty period is forwarded to

Alpha Omega Instruments Corp. and the directions received for properly
identifying items returned under warranty are followed;

(iv) the return notice authorizes Alpha Omega Instruments Corp. to examine

and disassemble returned products to the extent the Company deems
necessary to ascertain the cause of failure.

The warranties stated herein are exclusive. THERE ARE NO OTHER WARRANTIES, EITHER
EXPRESSED OR IMPLIED, BEYOND THOSE SET FORTH HEREIN, and Alpha Omega Instruments
Corp. does not assume any other obligation or liability in connection with the sale or use of said
products.

Disclaimer of Warranty
Alpha Omega Instruments makes no representation or warranties, either expressed or implied, by or with respect to
anything in this manual, including, but not limited to, implied warranties of merchantability or fitness for a particular
purpose. In no event will Alpha Omega Instruments Corp. be liable for any damages, whether direct or indirect,
special, consequential, or incidental arising from the use of this manual. Some states in the USA do not allow the
exclusion of incidental or consequential damages. Alpha Omega Instruments Corp. also reserves the right to make
any changes to improve the performance of its products at any time and without notice.

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ALPHA OMEGA INSTRUMENTS CORP.

DO NOT TOUCH!

THIS SYMBOL IS INTENDED TO ALERT THE USER TO THE
PRESENCE OF IMPORTANT OPERATING AND MAINTENANCE
INSTRUCTIONS.

WHEN POWERED, THE PRESENCE OF UN-INSULATED
DANGEROUS VOLTAGES WITHIN THE INSTRUMENT MAY BE
OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF
ELECTRICAL SHOCK RESULTING IN INJURY OR DEATH.
LEAVE ALL SERVICING TO QUALIFIED PERSONNEL.

REMOVE ALL POWER SOURCES WHEN INSTALLING OR
REMOVING AC POWER OR DATA SIGNAL CONNECTIONS
AND WHEN INSTALLING OR REMOVING THE SENSOR, OR
ELECTRONICS.

SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

WARNINGS

Explanation of graphic symbols

To avoid the risk of fire or electric shock, do not expose the Series 2000 Percent Oxygen Analyzer to
rain or water spray unless the enclosure is rated according to the National Electrical Manufacturer's
Association NEMA 4 (IP66)1 rating.

RF Disclaimer

This instrument generates and uses small amounts of radio frequency energy, and there is no
guarantee that interference will not occur in a particular installation. If this equipment does cause
interference to radio or television reception, try to correct the interference by one of more of the
following steps:

1. Reorient the receiving antenna.

2. Relocate the instrument with respect to the receiver.

3. Change the AC outlet of the instrument so the instrument and receiver are on different branch
circuits.

1 NEMA stands for the National Electrical Manufacturers Association and the designation IP"XX" signifies European IEC specifications 144 & 529.

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

TABLE OF CONTENTS

PAGE

WARRANTY i

WARNINGS ii

SECTION 1.0 INTRODUCTION 1

General Description 1

Measurement Ranges 1

Mechanical Configuration 1

Optional Equipment 2

Optional Battery Operation 2

RS-232C Option 2

RS-485 Option 3

Sample Filter Option 3

Filter Element Accessory 3

Flowmeter Option 3

Pressure Regulator Option 3

Sample Pump Option 3

Sensor Heater Option 3

General Specifications 4

SECTION 2.0 INSTALLATION PROCEDURES 6

Unpacking the Instrument 6

Electrical Installation 6

Wiring the AC/DC Power 6

Main Printed Circuit Board (Figure 1) 7

Oxygen Sensor 8

Wiring Alarm Relays 8

Wiring 4-20 mADC and 0-2 VDC Outputs 9

Wiring to the Optional RS-232C or RS-485 Outputs 10

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SECTION 3.0 SYSTEM DESCRIPTION 11

Extended Life Galvanic Sensor 11

Alarms 12

On Board Switch Settings 12

Fail-Safe Operation 13

Alarm Settings 13

SECTION 4.0 DETERMINING SYSTEM CONFIGURATION 14

Model Designation 14

SECTION 5.0 OPERATION 17

Preparation for Operation 17

AC Input Voltage Selection 17

Initial Setup 18

Mounting Configurations 18

Remote Mounted Sensor Enclosures 18

Operating Procedures 19

Power On 19

Front Panel Controls and Indicators 19

Setting the Alarms 20

Alarm Processing 20

Auto-Clear Operation 20

Manual Clear Operation 21

Timing Out 21

Over Range 21

TTL Signals for Analyzers with Autoranging 21

Manual Range Changing 21

Gas System Pressure Limits 22

Sample Connections 22

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SECTION 6.0 CALIBRATION PROCEDURES 23

Initial & Routine Calibration Checks 23

Calibration Gas 23

Procedure for Checking Calibration 23

Zero Adjustment 24

SECTION 7.0 REPLACEMENT OF THE OXYGEN SENSOR 25

Procedure for Replacing the Oxygen Sensor 25

SECTION 8.0 Optional Serial Communications RS232C & RS485 26

SECTION 9.0 Optional RS485 Enhanced Remote Control Commands 31

APPENDICES

Appendix A Bench Top/Portable Design/ Configuration 37

Part Number "BTP"

Appendix B Panel Mount Configurations 38

Part Numbers PNL, PNR, & PTX

Appendix C Remote Sensor Configuration, 42

Part Numbers "BTR & PNR"

Appendix D Explosion Proof Electronics/Sensor 43

Part Number "EXX".

Appendix E Explosion Proof Sensor Configuration 46

Part Number “BTX & PTX”

Appendix F Explosion Proof Sensor Housing Used with 47

BTX & PTX Configurations.

Appendix G Block Diagram for Remote 2000 PTX (Explosion Proof) 48

Appendix H MSDS for the 2SEN Oxygen Sensor 49

ADDENDA

Addendum 1 Optional Horn/Strobe Alarm 53

Addendum 2 Optional Internal Datalogger 56

Addendum 3 Optional High Volume Pump 58

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ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

SECTION 1.0

INTRODUCTION

1.1 General Description

The Series 2000 Percent Oxygen Analyzer is a microprocessor controlled instrument that can be
configured with either one or three percent oxygen ranges. The instrument is powered from either
115/230 VAC, 50-60Hz, or 18-32 VDC input. Battery operation is an option for the bench top/portable
version only. Oxygen values are displayed on a 10.2 mm (0.4") high 4-1/2 digit liquid crystal display
(LCD). The oxygen sensor is mounted in a PVC housing that contains 1/4" gas inlet and outlet
compression fittings. For the bench top/ portable instrument, the sensor housing is located on the rear
panel of the electronics enclosure. For instruments equipped with a remote sensor enclosure, the
sensor housing is either mounted on the enclosure, as is the case with the watertight NEMA 4X (IP 66)
and general purpose NEMA 1 enclosures, or inside the enclosure for the explosion proof, NEMA 7
types.

The front panel of the Series 2000 Percent Oxygen Analyzer contains five switches that provide
access to the analyzer's settings. The instrument is equipped with three oxygen alarm relays and one
status alarm relay. All four relays are Form C (SPDT) types rated at 10 amps at 115/230 VAC and 30
VDC. The relays are user configurable for fail-safe operation. In addition to the four alarm contacts,
the Series 2000 Percent Oxygen Analyzer has a built-in audible alarm and three red LED's for visual
indication of an oxygen alarm condition. The audible alarm may be manually canceled at anytime. If
the audible alarm is canceled, and the alarm event continues, indications of this condition will still be
available through the front panel LED's and relay contact(s).

The Series 2000 Percent Oxygen Analyzer comes equipped with two standard analog outputs, 4-20
mADC and 0-2 VDC. For enhanced communications, the Series 2000 Percent Oxygen Analyzer can
also be equipped with optional RS-232C or RS-485 serial communications. Another standard feature
of the Series 2000 Percent Oxygen Analyzer is autoranging (three range analyzers only). This feature
provides the analyzer with the capability to move either up or down the ranges of measurement
automatically.

1.2 Measurement Ranges with Range Code Designations (codes contained in model number).

Range Code Single Ranges Range Code Multiple Ranges
A 0-100% F 0-10/25/100%
B 0-25% G 0-5/10/25%
C 0-10% H 0-1/10/25%
D 0-5%

1.3 Mechanical Configurations with Part Number Designations.

Mechanical Code Description
BTP The analyzer enclosure is suitable for bench top or portable use and comes

equipped with a carrying handle. The sensor housing is mounted on the rear of
the enclosure (refer to Appendix A). The enclosure is fabricated from
polycarbonate.

PNL Similar to the BTP configuration with the addition of an aluminum panel frame.

It is not equipped with a carrying handle (refer to Appendix A). The enclosure is
made from polycarbonate with a watertight, NEMA 4X (IP66) rating.

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

BTR This configuration is comprised of two enclosures (electronics and sensor). The

electronics enclosure is suitable for bench top installations and is made from
polycarbonate with a watertight, NEMA 4X (IP66) rating. The sensor housing is
also made from polycarbonate and carries a NEMA 4X (IP66) rating (refer to
Appendix C). Three feet (1 meter) of interconnecting cable is standard with
additional cabling (up to 4,000 feet) (1,220 meters) available at the time of
order.

PNR Similar to the BTR configuration with the exception of the

electronics enclosure that is equipped with a steel panel frame.

BTX This configuration is comprised of two enclosures (electronics and sensor). The

electronics enclosure is suitable for bench top installations and is made from
polycarbonate with a watertight, NEMA 4X (IP66) rating. The oxygen sensor
housing is mounted inside an aluminum, explosion proof enclosure rated
NEMA 7 for use in areas requiring Class 1, Groups B,C,D, Division 1; Class II,
Groups E,F,G; and Class III protection (refer to Appendix D). Three feet (1
meter) of interconnecting cable is standard with additional cabling (up to 4,000
feet) (1,220 meters) available at the time of order.

PTX Similar to the BTX configuration with the exception of the electronics enclosure

that is equipped with a steel panel frame.

EXX In this configuration both the electronics and sensor are mounted within an

aluminum explosion proof enclosure rated NEMA 7 for use in areas requiring
Class 1, Groups B,C,D, Division 1; Class II, Groups E,F,G; and Class III
protection (refer to Appendix B).

1.4 Optional Equipment

The Series 2000 Percent Oxygen Analyzer Monitor incorporates standard features that make it
suitable for many applications. However, for certain requirements, the user may desire to augment
the capabilities of the instrument by equipping it with one or more options.

1.4.1 Battery Operation Part Number (P/N 2BAT)

The Series 2000 can be equipped so that it may be powered from a normal AC/DC source as well as
an optional built-in NiMH (nickel metal hydride) battery pack. The batteries are installed at the factory
and are designed for applications where the user desires to power the analyzer for short periods using
the batteries. With the battery option, the Series 2000 will operate for a period of at least 8 hours. If
equipped with a sample pump, operating time will be reduced to less than four hours of continuous
use. Other items such as alarms, use of the 4-20 mADC output, etc. could reduce the time intervals
between battery recharging. The Series 2000 is equipped with a “smart charging” capability for the
Nickel Metal Hydride (NiMH) battery pack. Smart charging eliminates the risk of the battery pack
being over-charged (not available with explosion proof systems). To achieve a full-charge after the
batteries have been discharged, allow for approximately 16 hours of charging time.

1.4.2 RS-232C Option (P/N 2RS2)

The RS-232C option is installed at the factory and is designed for applications where enhanced serial
communications is required between the Series 2000 Percent Oxygen Analyzer and a host system.
The maximum distance between monitor and host is 50 feet (15.2 meters).

1.4.3 RS-485 Option (P/N 2RS4)

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

The RS-485 option is installed at the factory and is designed for applications where enhanced serial
communications is required between one or several analyzers and a host system over the same
communications channel. The RS-485 format allows both sending and receiving of signals over
greater distances than RS-232C, making it ideal for installations where the analyzer(s) are located at
distances greater than 50 feet (15.2 meters) from the host. The maximum distance recommended
between devices is 4,000 feet (1,220 meters).

1.4.4 Sample Filter Option (P/N 295S)

Miniature T-type 316 stainless steel filter with 1/8" NPT in-line ports. Recommended when particle
loading exceeds 3 mg/ft3 and hydrocarbon mist exceeds 0.7 mg/ft3. Installed at the factory unless
otherwise specified by the customer. Other types of filters are available from Alpha Omega
Instruments. Please consult the factory for specific recommendations.

1.4.5 Filter Element Accessory (P/N 2FBX)

Filter element for the 395S

1.4.6 Flowmeter Option (P/N 2FLM)

Durable one piece clear acrylic flowmeter with easy to read scale in liters per minute.

1.4.7 Pressure Regulator Option (P/N 2PRR)

Stainless steel pressure regulator with a 3,000 psig (211 kg/cm2) inlet capacity and an adjustable
outlet pressure range of 0-5 psig (0 to 0.35 kg/cm2). The regulator does not include a gauge.

1.4.8 Sample Pump Option (P/N 2PMP)

Sample pump designed for applications where the sample pressure is insufficient to transport the
sample through the sensor housing.

1.4.9 Sensor Heater Option (P/N 2HTR)

Sensor heater used for applications where low ambient temperatures are encountered, or where
constant temperature conditions within the enclosure are desired. This option will not operate off
battery power and is only available with the EXX configuration.

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

1.4 General Specifications
Measurement Ranges (Percent Oxygen)

Single Range Multiple Range
0-100 0-10/25/100
0-25 0-5/10/25
0-10 0-1/10/25
0-5

Accuracy¹: ±1% of full scale (± 5% for ranges of 0-1%)

Linearity: ±1%

Response Time: 90% of full scale response in less than 20 seconds (typical)

Sensor Type: Ambient Temperature Electrochemical Sensor with EES

Temperature Compensation: Standard

Pressure Compensation: Standard

Operating Temperature: 40° to 104° F (5° to 40°C)

<40°F (<5°C) use heated sensor enclosure
>104°F (>40°C) cooling of sensor required

Warranty: 3 years electronics/ 2 years sensor

ELECTRICAL
Display: 0.4" (10.2 mm) high, 4-1/2digit LCD

Resolution: 0.1 %

Input Power: 115/230 VAC, 50-60Hz or 18-32 VDC, battery backup available

as an option for some models

Outputs: 4-20 mADC and 0-2 VDC standard as is a TTL output for range

identification. RS-232C or RS-485 serial communication optional.

Oxygen Alarm Relays: Three (3) SPDT Form C contacts rated 10A @ 30 VDC/115/230

VAC. User selectable for fail-safe or non fail-safe.

Instrument Status Alarm: Rated identically to the O2 relays

Audible Alarm: Internal buzzer with audible cancel

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ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

SAMPLE GAS CHARACTERISTICS
Flow Rate: 1.0 to 2.0 SCFH (0.5 to 1.0 liter/min)

Sample Gas Temperature: 32° to 104° F (0° to 40°C)

Sample Gas Pressure Limits: 0.1 to 1.5 psig (0.007 to 0.1 kg/cm2).

Entrained Solids: <3 mg/ft³: no in-line filter required

>3 mg/ft³: in-line filter is required

Hydrocarbon Mist: <0.7 mg/ft³: no in-line filter required

>0.7 mg/ft³: in-line filter is required

CONSTRUCTION²
Electronics Control Unit: Polycarbonate with a hinged clear front cover, rated NEMA 4X

(IP 66)

Control Unit Dimensions: 9.45 in. (240.5 mm) length

6.50 in. (165.1 mm) width

6.20 in. (157.5 mm) depth
Note: All dimensions are without optional equipment

Gas Connections: Quick connect for 1/4” OD flex tubing or optional 1/4” stainless
steel compression fittings

Sensor Mounting: Local or optional remote mounting

Weight: 11lbs (4.98 kg) (Bench-top Configuration.)

¹ Stated at constant temperature and constant pressure.
² Other mechanical configurations available-consult factory.

Alpha Omega Instruments Corp. reserves the right to change or modify its product specifications without notice.

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ALPHA OMEGA INSTRUMENTS CORP.

NOTE: IF DAMAGE HAS BEEN FOUND, DO NOT PROCEED
FURTHER, BUT INSTEAD, CONTACT THE FACTORY.

ELECTRICAL INSTALLATION SHOULD BE PERFORMED BY A
CERTIFIED ELECTRICIAN AND SHOULD COMPLY WITH APPLI­CABLE FEDERAL, STATE, OR LOCAL ELECTRICAL SAFETY
CODES.

SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

SECTION 2.0

Installation procedures

2.1 Unpacking the Instrument

Upon opening the shipping container, carefully unpack the instrument to check if the outer surfaces
have been damaged. If so, report the findings immediately to Alpha Omega Instruments who will, in
turn, provide further instructions.

If there is no apparent damage, check the contents to ensure all items were shipped. In some cases,
items may be back-ordered. All damage and shortage claims must be made known to Alpha

Omega Instruments within 10 days after receipt of shipment.

There are six screws on the Series 2000 Percent Oxygen Analyzer that fasten the clear cover to the
polycarbonate enclosure. Loosen these screws to disengage them from the enclosure, and open the
cover exposing the front panel membrane switches. For the explosion proof version, their are 18
fastening bolts that need to be removed in order to remove the cover from the base. The membrane
panel is installed on a metal backing plate that is hinged and swings out in the same direction as the
cover. Swing out the membrane panel and check inside the control unit to make sure no components
have been loosened or dislodged. If there are loose or dislodged components, notify the factory for
further instructions. If all is found to be satisfactory, the installation procedure can begin.

2.2 Electrical Installation

The Series 2000 Percent Oxygen Analyzer is shipped with a power cord (except for the explosion
proof versions). Some installations may require wiring through conduit into the electrical hub on the
rear panel (where the existing power cord is installed). For such installations, removal of the existing
power cord can be easily accomplished as described in section 2.2.1. The position of jumper S2,
which is located at the lower left quadrant of the printed circuit board determines the line voltage
setting. The default setting is 115 VAC, 50-60Hz. If the AC input voltage is changed in the field,

please refer to Section 5.1.1 for instructions.

2.2.1 Wiring the AC/DC Power in Place of the Existing Power Cord

Referring to the printed circuit board diagram (FIGURE 1.0) on the next page, locate the AC power
terminals 31,32, and 33. Each connector is equipped with a screw terminal wire holder to facilitate
insertion or removal of the wire from the connector. Strip away approximately 6.0 mm (1/4 inch) of
insulation from each of the three conductors and then connect AC line, AC neutral, and chassis
ground to each connector. Tighten down on each screw turning clockwise to securely fasten each
conductor. If the primary power to the instrument is direct current (DC), wire to terminals 29 (BAT+)
and 30 (BAT-). Please refer to the cautionary note on page 17 regarding optional battery operation.

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ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

FIGURE 1.0

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

2.2.2 Oxygen Sensor

Wiring of the oxygen sensor has been done at the factory. For information regarding sensor
replacement, please refer to Section 7.0.

2.2.3 Wiring Alarm Relays

In addition to the cable used for the AC/DC power to the Control Unit, access to the control signals
generated from the Series 2000 Percent Oxygen Analyzer is accomplished using signal cabling. This
cable is installed through the output cable gland on the rear of the electronics enclosure. The number
of conductors needed is determined by the number of functions to be controlled.

The Series 2000 Percent Oxygen Analyzer is equipped with four single pole double throw (SPDT)
relays with Form C contacts rated at 10 amperes @ 30 VDC and 115/230 VAC. All alarm relays are
user configurable with the three oxygen alarms defaulting to factory setting of low oxygen alarms. To
configure any of the three oxygen alarm relays to act as high alarms, please refer to Section 5.2.3. As
a reminder, Alarm 4 which is not displayed as a discrete alarm on the front panel, is the instrument
status alarm.

The technique for wiring to the connectors is identical to that discussed in Section 2.2.1. The wiring
configuration is as follows:

Terminal Alarm 1 Relay

26 Common Contact
27 Normally Open Contact
28 Normally Closed Contact

Alarm 2 Relay

23 Common Contact
24 Normally Open Contact
25 Normally Closed Contact

Alarm 3 Relay

20 Common Contact
21 Normally Open Contact
22 Normally Closed Contact

Instrument Status Alarm

17 Common Contact
18 Normally Open Contact
19 Normally Closed Contact

TABLE 1.0 on the next page illustrates the various wiring configurations for the four alarms in the
Series 2000 Percent Oxygen Analyzer based on whether the alarms are going to be configured for
fail-safe or non fail-safe operation.

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

Alarm ONContacts

shorted for

Fail-safe OFFFail-safe ON

each Alarm

Relay

High or Low O2

Alarm1 /

Relay 1

High or Low O2

Alarm2 /

Relay 2

High or Low O2

Alarm3 /

Relay 3

Low Battery or

Instrument

Status/ Relay 4

Each of the aforementioned alarm relays can be individually configured for fail-safe operation by
means of a DIP switch located on the main printed circuit board (refer to Section 3.3). If the
instrument is equipped with optional RS-232C or RS-485 communications, the alarms can also be
controlled via these outputs. See the caution note below.

28(NC) to

26(COM)

25(NC) to

23(COM)

22(NC) to

20(COM)

19(NC) to

17(COM)

TABLE 1.0

27(NO) to

26(COM)

24(NO) to

23(COM)

21(NO) to

20(COM)

18(NO) to

17(COM)

IF THE SERIES 2000 PERCENT OXYGEN ANALYZER IS EQUIPPED
WITH EITHER RS-232C OR RS-485 COMMUNICATIONS, PLEASE
REFER TO SECTION 8.0.

2.2.4 Wiring 4-20 mADC and 0-2 VDC Outputs

The Series 2000 Percent Oxygen Analyzer has two standard linear outputs, 4-20 mADC and 0-2 VDC
over the instrument's range(s). These outputs can be measured simultaneously. To wire to the 4-20
mADC output, wire to terminals 12 (4-20) and 13 (AGND). To wire to the 0-2 VDC output, use
terminals 8 (positive {labeled DAC}) and 9 (negative {labeled AGND} ). The terminals can be found on
the right side of the printed circuit board (refer to FIGURE 1.0). Note: If a jumper wire is in place

between terminals 12 and 13, it must be removed prior to using the 4-20 mADC output.

NOTE: IF THE 4-20MA DC OUTPUT IS NOT GOING TO
BE USED, IT SHOULD BE SHORTED TO AVOID AN
OPEN LOOP WARNING VIA TERMINAL 10 (B-LO)

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ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

2.2.5 Wiring to the Optional RS-232C or RS-485 Outputs.

The RS-232C and RS-485 digital communications are options with the Series 2000 Percent Oxygen
Analyzer. Unlike the analog outputs, the Series 2000 Percent Oxygen Analyzer can be ordered with
either option, but not both. To wire for either the RS-232C or RS-485, use terminals 14 (TXD) for
transmit and 15 (RXD) for receive. Note: You must connect the GND terminal for RS-232C and

RS-485 for the instrument to work properly. Further details on these communication channels
are contained in Section 8.0. Section 8.0 is included as part of this manual even if the Series
2000 Percent Oxygen Analyzer has not been equipped with either of the two aforementioned
digital communication loops.

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ALPHA OMEGA INSTRUMENTS CORP.
SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

SECTION 3

SYSTEM DESCRIPTION

3.1 Extended Life Galvanic Sensor

The Series 2000 Percent Oxygen Analyzer features an extended life oxygen sensor with a weak acid
electrolyte system. The weak acid electrolyte system retards passivation of the sensor anode by
allowing the products of oxidation to dissolve in the acid electrolyte. In effect, the sensor is renewed
continuously as the weak acid electrolyte tolerates over 20 times the lead oxide (PbO) than potassium
hydroxide (KOH) based sensors. The result is a sensor with a greatly extended useful life.

The extended life sensor is a lead-oxygen battery comprised of a lead anode, and gold cathode, and a
weak acid electrolyte. A gold electrode is bonded onto a non-porous Teflon (FEP) membrane. A small
amount of oxygen permeating through the membrane is reduced electrochemically at the gold
electrode. A resistor and a thermistor (for temperature compensation) are connected between the
cathode and anode. As a result, the lead-oxygen battery is always discharged.

Current flowing through the resistor and thermistor is proportional to the oxygen concentration of the
gas in contact with the Teflon membrane. By measuring the voltage between the resistor and the
thermistor, oxygen concentration can be accurately determined. The two electrode reactions are
depicted below:

Cathode: O2 + 4H+ + 4e 2H2O

Anode: 2Pb + 2H2O 2PbO + 4H+ + 4e

Overall: O2 + 2Pb 2PbO

If PbO generated at the anode remains on the anode, the anode's potential will change and the output
voltage of the sensor would become extremely low. However, in actuality the surface of the lead
anode is continuously renewed because PbO is dissolved back into the electrolyte.

There is a maximum level to the solubility of PbO in the weak acid electrolyte. As a result, when the
electrolyte becomes saturated with PbO, the sensitivity of the sensor will begin to drop signaling time
for replacement of the sensor. When the extended life oxygen sensor is used in ambient air monitoring
applications, carbon dioxide (CO2) that is present will not adversely affect the sensor's performance.
Due to the weak acid electrolyte, CO2 will not react with the electrolyte to form potassium carbonate as
it does with KOH based sensors. As a result, there is no loss in output due to the presence of CO2.

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SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

3.2 Alarms

One of the primary functions of the instrument is to alert the user when alarm conditions have
occurred. To this end, four alarm relays, each capable of switching up to 10 Amperes, are provided.
These isolated relays are single pole double throw (SPDT) relays for maximum user flexibility. These
relay outputs, along with the simultaneous LED and annunciator operation, serve to give maximum
notification to the user of an alarm condition.

An "open collector" output, more appropriately called an "open drain output", in this case, provides an
additional level of operator output for signaling alarm purposes. This "open drain output", from a 50
volt MOSFET transistor, is normally open, but will close or short to ground to indicate an alarm
condition if the 4 to 20 milliamp loop is open.

The front panel display and Relay #4 will indicate a low battery if the instrument is equipped with the
Battery Backup option.

3.3 On Board Switch Settings

Setting the alarms for fail-safe operation and automatic alarm clearing can be accomplished by using
an on board switch bank (SW6) located in the upper right quadrant of the printed circuit board (refer to
FIGURE 1.0). This switch bank has eight (8) individual switches for configuring the Series 2000
Percent Oxygen Analyzer. Refer to FIGURE 3.0 on the next page for a description of the switches.

The Series 2000 Percent Oxygen Analyzer is shipped from the factory with switch #8 in the "OFF"
("switch settings" mode) position. This is the default configuration and will force the Series 2000
Percent Oxygen Analyzer to read the other switches in order to configure the alarms when power is
applied or a warm boot has occurred. If switch #8 is in the "ON" ("user configuration" mode) position,
the Series 2000 Percent Oxygen Analyzer will be configured using battery backed configuration
information. This means the analyzer will ignore the switch settings altogether and "boot" up to user
configured memory. The user configured memory is that which is set up via the front panel or external
communications loop (refer to Section 5.2.2).

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ALPHA OMEGA INSTRUMENTS CORP.

SW6

O

N

1 2 3 4 5 6 7 8

RELAY 1 - NORMAL

RELAY 2 - NORMAL

RELAY 3 - NORMAL

RELAY 4 - NORMAL

OXYGEN ALARM 3 (LO)

MANUALLY CLEAR ALARMS

SWITCH SETTINGS

RESERVED

RELAY 1 - FAIL-SAFE

RELAY 2 - FAIL-SAFE

RELAY 3 - FAIL-SAFE

RELAY 4 - FAIL-SAFE

OXYGEN ALARM 3 (HI)

AUTO CLEAR ALARMS

USER CONFIGURATION

RESERVED

SW6

SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

3.3.1 Fail-Safe Operation

The Series 2000 Percent Oxygen Analyzer will "boot" up based on the settings of oxygen alarm
switches #1 through #4. Switches #1 through #4 control the fail-safe operation for each of the four
alarm relays. Each switch must be turned "ON" to be fail-safe (refer to FIGURE 3.0). In the fail-safe
mode, upon an alarm condition, the corresponding relay will change state (from energized to de­energized) upon loss of AC power. The factory settings for switches #1 through #4 is "OFF" (normal
operation or non fail-safe).

3.3.2 Alarm Settings

With switch #8 in the "OFF" position, the Series 2000 Percent Oxygen Analyzer defaults to configuring
all three Oxygen Alarms as low alarms. With switch #8 in the "ON" position, all user settings will be
retained. Note: to read the switches while operating, just perform a "warm boot". (See Section 5.2.1)

FIGURE 3.0

IF ANY ALARM IS NOT GOING TO BE USED, IT SHOULD
BE DISABLED. TO DO SO, FIRST CONFIGURE EACH
ALARM AS A LOW ALARM, AND THEN SET THE ALARM
TO 0.00

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ALPHA OMEGA INSTRUMENTS CORP.

P/N KEY:

A

Code Base Model

2000

Series 2000 Percent Oxygen Analyzer with three alarm relays, instrument

status alarm relay, digital display, audible alarm, visual alarm indicators,
NEMA 1 enclosure, 4-20 mADC, and 0-2 VDC analog outputs.

B

Oxygen Ranges

Range Code Range

A 0-100%
B 0-25%
C 0-10%
D 0-5%
E

Left Blank

F 0-10/25/100%
G 0-5/10/25%
H 0-1/10/25%

C

Code Input Power

115 115 VAC
50-60 Hz

230 230 VAC

50 Hz

Input Power Configurations

A

B C

D

Base Model

Code

Range

Code

Input
Code

Mechanical

Configuration Code

SERIES 2000 PERCENT OXYGEN ANALYZER Instruction Manual

SECTION 4.0

DETERMINING SYSTEM CONFIGURATION

4.1 Model Designation

Before proceeding to the following sections, it is important to determine the system configuration for
the selected analyzer. To best accomplish this, refer to the purchase order to obtain the part number
that was ordered and compare it to the range, input power configuration, and mechanical configuration
shown below.

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