Rosemount 755A User manual

Rosemount Analytical
MODEL 755A
OXYGEN ANALYZER
INSTRUCTION MANUAL
245364-U

NOTICE
The information contained in this document is subject to change without notice.
Manual Part Number 245364-U
April 2000
Printed in U.S.A.
Rosemount Analytical Inc.
4125 East La Palma Avenue
Anaheim, California 92807-1802
Teflon® is a registered trademark of E.I. duPont de Nemours and Co., Inc.
SNOOP® is a registered trademark of NUPRO Co.

CONTENTS
245364-U Rosemount Analytical April 2000 i
Model 755A Oxygen Analyzer
PREFACE
INTENDED USE STATEMENT ............................................................................P-1
SAFETY SUMMARY ............................................................................................P-1
SPECIFICATIONS - GENERAL ...........................................................................P-3
SPECIFICATIONS - SAMPLE..............................................................................P-3
SPECIFICATIONS - ELECTRICAL.......................................................................P-4
SPECIFICATIONS - PHYSICAL...........................................................................P-5
CUSTOMER SERVICE, TECHNICAL ASSISTANCE AND FIELD SERVICE......P-6
RETURNING PARTS TO THE FACTORY...........................................................P-6
TRAINING ........................................................................................................P-6
DOCUMENTATION..............................................................................................P-6
COMPLIANCES ...................................................................................................P-7
SECTION 1. INTRODUCTION
1.1 OVERVIEW ..............................................................................................1-1
1.2 OXYGEN RANGE ON FRONT PANEL DIGITAL DISPLAY.....................1-2
1.3 OXYGEN RANGES FOR RECORDER READOUT..................................1-2
1.4 RECORDER VOLTAGE AND CURRENT OUTPUTS..............................1-3
1.5 AUTOMATIC PRESSURE COMPENSATION..........................................1-3
1.6 ALARM (OPTION)....................................................................................1-3
1.7 CASE MOUNTING OPTIONS ...................................................................1-3
1.8 ELECTRICAL POWER OPTIONS............................................................1-3
SECTION 2. UNPACKING AND INSTALLATION
2.1 UNPACKING ............................................................................................2-1
2.2 LOCATION ...............................................................................................2-1

CONTENTS
ii April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
SECTION 2. (CONTINUED)
2.2.1 Location and Mounting............................................................... 2-1
2.3 VOLTAGE REQUIREMENTS .................................................................. 2-1
2.4 ELECTRICAL CONNECTIONS................................................................ 2-2
2.4.1 Line Power Connections............................................................. 2-2
2.4.2 Recorder Connections................................................................ 2-2
2.4.3 Output Connections for Dual Alarm Option ................................ 2-5
2.5 CALIBRATION......................................................................................... 2-8
2.5.1 Zero Calibration Gas .................................................................. 2-8
2.5.2 Downscale Standard Gas........................................................... 2-8
2.5.3 Upscale Standard Gas ............................................................... 2-8
2.6 SAMPLE HANDLING............................................................................... 2-8
2.6.1 Sample Temperature Requirements........................................... 2-8
2.6.2 Sample Pressure Requirements: General................................. 2-9
2.6.3 Normal Operation at Positive Gauge Pressures......................... 2-10
2.6.4 Operation at Negative Gauge Pressures.................................... 2-10
2.6.5 Sample Flow Rate...................................................................... 2-10
2.6.6 Corrosive Gases........................................................................ 2-11
2.7 LEAK TEST.............................................................................................. 2-11
2.8 PURGE KIT (OPTIONAL) ........................................................................ 2-12
SECTION 3. INITIAL STARTUP AND CALIBRATION
3.1 SELECTION OF RECORDER OXYGEN RANGE ................................... 3-1
3.1.1 Recorder Oxygen Range Selection Procedure........................... 3-1
3.1.2 Readout of Applied Zero-Suppression Voltage on
Digital Display............................................................... 3-5
3.2 STARTUP PROCEDURE......................................................................... 3-6
3.3 CALIBRATION......................................................................................... 3-7
3.3.1 Calibration Using Digital Readout for Oxygen Readout.............. 3-7
3.3.2 Calibration Using Recorder for Oxygen Readout ....................... 3-7
3.3.3 Calibration with Downscale and Upscale Standard Gases......... 3-8
3.3.4 Calibration of Automatic Pressure Compensation...................... 3-9
3.4 COMPENSATION FOR COMPOSITION OF BACKGROUND GAS........ 3-10
3.4.1 Oxygen Equivalent Values of Gases.......................................... 3-11
3.4.2 Computing Adjusted Settings for Zero and Span Controls......... 3-11
3.5 DUAL ALARM OPTION ........................................................................... 3-13
3.5.1 Inital Calibration and Selection of Setpoints for Alarms.............. 3-13
3.5.2 Selection of Deadband............................................................... 3-14

CONTENTS
245364-U Rosemount Analytical April 2000 iii
Model 755A Oxygen Analyzer
SECTION 4. ROUTINE OPERATION
4.1 ROUTINE OPERATION ...........................................................................4-1
4.2 EFFECT OF BAROMETRIC PRESSURE CHANGES ON
INSTRUMENT READOUT............................................................4-1
4.3 CALIBRATION FREQUENCY ..................................................................4-1
SECTION 5. THEORY
5.1 PRINCIPLES OF OPERATION ................................................................5-1
5.2 VARIABLES INFLUENCING PARAMAGNETIC OXYGEN
MEASUREMENTS........................................................................5-5
5.2.1 Pressure Effects..........................................................................5-5
5.2.2 Temperature Effects....................................................................5-5
5.2.3 Interferents.................................................................................5-6
5.2.4 Vibration Effects..........................................................................5-6
5.3 ELECTRONIC CIRCUITRY......................................................................5-6
5.3.1 Detector/Magnet Assembly.........................................................5-7
5.3.2 Control Board and Associated Circuitry ......................................5-7
5.3.3 Case Board.................................................................................5-9
5.3.4 Isolated Current Output Board (Optional)....................................5-10
5.3.5 Alarm Option...............................................................................5-10
SECTION 6. ELECTRONIC CIRCUIT ANALYSIS
6.1 OVERVIEW ..............................................................................................6-1
6.2 ±15VDC POWER SUPPLY.......................................................................6-1
6.3 CASE HEATER CONTROL CIRCUIT ......................................................6-1
6.4 DETECTOR HEATER CONTROL CIRCUIT ............................................6-6
6.5 DETECTOR LIGHT SOURCE CONTROL CIRCUIT................................6-7
6.6 DETECTOR WITH FIRST STAGE AMPLIFIER AND PRESSURE
COMPENSATION CIRCUITS.......................................................6-8
6.7 BUFFER AMPLIFIERS U10 AND ASSOCIATED ANTICIPATION
FUNCTION....................................................................................6-12
6.8 DIGITAL OUTPUT CIRCUIT.....................................................................6-12
6.9 ANALOG OUTPUT CIRCUITS FOR RECORDER AND ALARMS...........6-13

CONTENTS
iv April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
SECTION 7. ROUTINE SERVICE AND MAINTENANCE
7.1 INITIAL CHECKOUT WITH STANDARD GASES.................................... 7-1
7.2 DETECTOR COMPONENT CHECKS..................................................... 7-2
7.2.1 Detector ..................................................................................... 7-2
7.2.2 Source Lamp.............................................................................. 7-2
7.2.3 Photocell..................................................................................... 7-2
7.2.4 Suspension................................................................................. 7-3
7.3 DETECTOR COMPONENT REPLACEMENT ......................................... 7-3
7.3.1 Detector Replacement................................................................ 7-3
7.3.2 Source Lamp Replacement........................................................ 7-5
7.3.3 Photocell Replacement and Adjustment..................................... 7-7
7.4 HEATING CIRCUITS............................................................................... 7-8
7.4.1 Case Heater Control Circuit........................................................ 7-8
7.4.2 Detector/Magnet Heating Circuit ................................................ 7-9
SECTION 8. REPLACEMENT PARTS
8.1 CIRCUIT BOARD REPLACEMENT POLICY........................................... 8-1
8.2 SELECTED REPLACEMENT PARTS ..................................................... 8-1
GENERAL PRECAUTIONS FOR STORING AND HANDLING HIGH PRESSURE GAS CYLINDERS
WARRANTY
FIELD SERVICE AND REPAIR FACILITIES

CONTENTS
245364-U Rosemount Analytical April 2000 v
Model 755A Oxygen Analyzer
FIGURES
1-1 Model 755A Oxygen Analyzer..................................................................1-1
1-2 Analyzer Components and Adjustments Locations ..................................1-4
2-1 Electrical Connections..............................................................................2-3
2-2 Control Board ...........................................................................................2-4
2-3 Connections for Potentiometric Recorder with Non-Standard Span.........2-4
2-4 Analyzer Connected to Drive Several Current-Activated Output
Devices .........................................................................................2-5
2-5 Typical Alarm Settings..............................................................................2-7
2-6 Relay Terminal Connections for Typical Fail-Safe Application.................2-7
2-7 Connection of Typical Gas Selector Panel to Analyzer ............................2-9
2-8 Installation of Purge Kit (Optional)............................................................2-13
3-1 Front Panel Controls.................................................................................3-2
3-2 Internal Adjustments Locations.................................................................3-5
3-3 Calibration by Pressure Decrease Setup..................................................3-9
3-4 Schematic Circuit of Alarm Relay Assembly.............................................3-14
5-1 Spherical Body in Non-Uniform Magnetic Field........................................5-2
5-2 Functional Diagram of Paramagnetic Oxygen Measurement System ......5-3
5-3 Detector/Magnet Assembly.......................................................................5-4
6-1 Two-Comparator OR Circuit.....................................................................6-2
6-2 Ramp Generator.......................................................................................6-3
6-3 Case Heater Control Circuit......................................................................6-4
6-4 Case Heater Circuit..................................................................................6-5
6-5 Detector Heater Control Circuit.................................................................6-7
6-6 Detector Light Source Control Circuit.......................................................6-8
6-7 Detector with First Stage Amplifier and Pressure Compensation
Circuits..........................................................................................6-11
6-8 Pressure Signal and Reference Voltage Circuits......................................6-11
6-9 Buffer, Anticipation, and Digital Output Circuit..........................................6-12
6-10 Simplified Analog Output Circuit for Recorder (Showing Three
Ranges).........................................................................................6-15
7-1 Detector/Magnet Assembly.......................................................................7-4
7-2 Detector/Magnet Assembly Wiring ...........................................................7-5
7-3 Detector Adjustment.................................................................................7-5
7-4 Modifiication of 633689 Connector Board for Compatibility with
Replacement Lamp.......................................................................7-7
7-5 Lamp Alignment.........................................................................................7-7
TABLES
3-1 Internal Adjustments.................................................................................3-4
3-2 Standard Gases Recommended for Calibration of Various Oxygen
Ranges on Analog Output.............................................................3-8
3-3 Oxygen Equivalents of Common Gases...................................................3-12

CONTENTS
vi April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
DRAWINGS (LOCATED IN REAR OF MANUAL)
617186 Schematic Diagram, Master Board Assembly (Case)
617731 Pictorial Wiring Diagram, Model 755A
620434 Schematic Diagram, 0 to 20 mA or 4 to 20 mA Current Output
632349 Installation Drawing, Model 755A
652219 Schematic Diagram, Control Board
652222 Schematic Diagram, Transducer

PREFACE
245364-U Rosemount Analytical April 2000 P-1
Model 755A Oxygen Analyzer
INTENDED USE STATEMENT
The Model 755A is intended for use as an industrial process measurement device
only. It is not intended for use in medical, diagnostic, or life support applications, and
no independent agency certifications or approvals are to be implied as covering such
applications.
SAFETY SUMMARY
To avoid explosion, loss of life, personal injury and damage to this equipment and
on-site property, all personnel authorized to install, operate and service the Model
755A Oxygen Analyzer should be thoroughly familiar with and strictly follow the
instructions in this manual. Save these instructions.
DANGER is used to indicate the presence of a hazard which will cause severe
personal injury, death, or substantial property damage if the warning is ignored
WARNING is used to indicate the presence of a hazard which can cause severe
personal injury, death, or substantial property damage if the warning is ignored.
CAUTION is used to indicate the presence of a hazard which will or can cause minor
personal injury or property damage if the warning is ignored.
NOTE is used to indicate installation, operation, or maintenance information which is
important but not hazard-related.
Do not operate without doors and covers secure. Servicing requires access to
live parts which can cause death or serious injury. Refer servicing to qualified
personnel.
For safety and proper performance this instrument must be connected to a
properly grounded three-wire source of power.
WARNING: ELECTRICAL SHOCK HAZARD

PREFACE
P-2 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
WARNING: POSSIBLE EXPLOSION HAZARD
WARNING: HIGH PRESSURE GAS CYLINDERS
CAUTION: PARTS INTEGRITY
This analyzer is of a type capable of analysis of sample gases which may be
flammable. If used for analysis of such gases, the instrument must be either in
an explosion-proof enclosure suitable for the gas, or, protected by a continuous
dilution purge system in accordance with Standard ANSI/NFPA-496-1086
(Chapter 8) or IEC Publication 79-2-1983 (Section Three).
If gases are introduced into this analyzer, the sample containment system must
be carefully leak-checked upon installation and before initial start-up, during
routine maintenance and any time the integrity of the sample containment
system is broken, to ensure the system is in leak-proof condition. Leak-check
instructions are provided in Section 2.7.
Internal leakage of sample resulting from failure to observe these precautions
could result in an explosion causing death, personal injury, or property damage.
Tampering or unauthorized substitution of components may adversely affect
safety of this product. Use only factory documented components for repair.
This analyzer requires periodic calibration with known zero and standard gases.
Refer to Sections 2.5 and 2.6. See also General Precautions for Handling and
Storing High Pressure Cylinders, in the rear of this manual.

PREFACE
245364-U Rosemount Analytical April 2000 P-3
Model 755A Oxygen Analyzer
SPECIFICATIONS - GENERAL
OPERATING RANGE
0.00% to 100.0% oxygen
RECORDER RANGE
Selectable for 0% to 100% oxygen or for any desired span of 1%, 2%, 5%,
10%, 20% or 100% oxygen within the overall range.
RESPONSE TIME
(90% of fullscale) recorder output factory set for 20 seconds; adjustable from 5
to 25 seconds.
REPRODUCIBILITY (DIGITAL DISPLAY)
±0.01% Oxygen ±2 counts.
AMBIENT TEMPERATURE LIMITS
Maximum: 49°C (120°F) EXCEPT 38°C (100°F) for 99% to 100% oxygen.
Minimum: -7°C (20°F) EXCEPT 4°C (40°F) for 99% to 100% oxygen.
ZERO AND SPAN DRIFT1
Within ±1% of fullscale (±2% of fullscale for 99% to 100% range) per 24 hours,
provided that ambient temperature does not change by more than 11.1°C
(20°F).
±2.5% of fullscale per 24 hours with ambient temperature change over entire
range.
BAROMETRIC PRESSURE COMPENSATION
Oxygen readout automatically corrected to within ±1% of fullscale for
barometric pressure variations within ±3% of target value and within ±2% of
fullscale for barometric pressure variations within ±5% of target value.
The target may be set anywhere within range of -2.7 to 3.3 psig ±3 psig (-18.6
to 22.8 kPa ±21 kPa).
Exhaust vented to atmosphere.
SPECIFICATIONS - SAMPLE
DRYNESS
Sample dewpoint below 43°C (110°F), sample free of entrained liquids.
TEMPERATURE LIMITS
Maximum: 66°C (150°F)
Minimum: 10°C (50°F)
1Zero and span drift specifications based on following conditions: Operating pressure constant; ambient temperature
change from initial calibration temperature, less than 11.1 Celsius degrees (20 Fahrenheit degrees); deviation from set
flow held to within ±10% or ±20 cc/min, whichever is smaller.

PREFACE
P-4 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
SPECIFICATIONS - SAMPLE (CONTINUED)
OPERATING PRESSURE
Maximum: 69 kPa (10 psig).
Minimum: -13.1 kPa (-1.9 psig)
FLOW RATE 2
Maximum: 500 cc/min
Minimum: 50 cc/min
Recommended: 250 ±20 cc/min
MATERIALS IN CONTACT WITH SAMPLE GAS
316 stainless steel, glass, titanium, Paliney No. 7, epoxy resin, Viton-A,
platinum, nickel.
SPECIFICATIONS - ELECTRICAL
SUPPLY VOLTAGE AND FREQUENCY
Standard: 115 VAC ±10 VAC, 50/60 Hz
Optional: 230 VAC ±10 VAC, 50/60 Hz
POWER CONSUMPTION
Maximum: 300 watts
Nominal: 75 watts
OUTPUT
Standard: Field selectable voltage output of 0 to 10mV, 0 to 100mV, 0 to 1V,
or 0 to 5VDC
Optional: Isolated current output of 0 to 20mA or 4 to 20mA (with Current
Output Board)
ALARM OPTION
High-Low Alarm
Contact Ratings:
5 amperes, 240V AC, resistive load
5 amperes, 120V AC, resistive load
5 amperes, 28V DC, resistive load
SETPOINT
Adjustable from 1% to 20% of fullscale
DEADBAND
Adjustable from 1% to 20% of fullscale (Factory set at 10% of fullscale)
2Deviation from set flow would be held to within ±10% or ±20 cc/min, whichever is smaller. If so, zero and span drift will
be within specifications, provided that operating temperature remains constant.

PREFACE
245364-U Rosemount Analytical April 2000 P-5
Model 755A Oxygen Analyzer
SPECIFICATIONS - PHYSICAL
MOUNTING
Standard: Panel mount
Optional: Surface or stanchion mount accessory available
ENCLOSURE CLASSIFICATION
Meets requirements for NEMA 3R
Air Purge Option3: NFPA 496 (1989) Type Z purge
WEIGHT
Approximately 32.5 lbs (14.74 Kg)
DIMENSIONS
Height: 13.5 (343 mm)
Width: 11.5 (294 mm)
Depth: 7.12 (181 mm)
3When installed with user supplied components, meets requirements for Class I, Division 2 locations per National
Electrical Code (ANSI/NFPA 70) for analyzers sampling nonflammable gases. Analyzers sampling flammable gases
must be protected by a continuous dilution purge system in accordance with Standard ANSI/NFPA 496-1986, Chapter 8.
Consult factory for recommendations.

PREFACE
P-6 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
CUSTOMER SERVICE, TECHNICAL ASSISTANCE AND FIELD SERVICE
For order administration, replacement Parts, application assistance, on-site or factory
repair, service or maintenance contract information, contact:
Rosemount Analytical Inc.
Process Analytical Division
Customer Service Center
1-800-433-6076
RETURNING PARTS TO THE FACTORY
Before returning parts, contact the Customer Service Center and request a Returned
Materials Authorization (RMA) number. Please have the following information when
you call: Model Number, Serial Number, and Purchase Order Number or Sales Order
Number.
Prior authorization by the factory must be obtained before returned materials will be
accepted. Unauthorized returns will be returned to the sender, freight collect.
When returning any product or component that has been exposed to a toxic, corrosive
or other hazardous material or used in such a hazardous environment, the user must
attach an appropriate Material Safety Data Sheet (M.S.D.S.) or a written certification
that the material has been decontaminated, disinfected and/or detoxified.
Return to:
Rosemount Analytical Inc.
4125 East La Palma Avenue
Anaheim, California 92807-1802
TRAINING
A comprehensive Factory Training Program of operator and service classes is
available. For a copy of the Current Operator and Service Training Schedule contact
the Technical Services Department at:
Rosemount Analytical Inc.
Phone: [phone]
FAX: [phone]
DOCUMENTATION
The following Model 755A Oxygen Analyzer instruction materials are available.
Contact Customer Service or the local representative to order.
245364 Instruction Manual (this document)

PREFACE
245364-U Rosemount Analytical April 2000 P-7
Model 755A Oxygen Analyzer
COMPLIANCES
The Model 755A Oxygen Analyzer (General Purpose Enclosure) has been designed to
meet the applicable requirements of the U.S. Occupational Safety and Health Act
(OSHA) of 1970 if installed in accordance with the requirements of the National
Electrical Code (NEC) of the United States in non-hazardous areas and operated and
maintained in the recommended manner.
This product may carry approvals from a certifying agency or may be in compliance
with EMC Directive. If so, the product will carry approval insignia, like those shown
here, on the product name rating plate.
®

PREFACE
P-8 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
NOTES

1
INTRODUCTION
245364-U Rosemount Analytical April 2000 1-1
Model 755A Oxygen Analyzer
6 Digit LCD Display
ZERO Adjust
Rosemount Analytical Model 755A
Oxygen Analyzer
PRESS CAL1 PRESS CAL 2
NORM REC OFFSET SPAN Adjust
TEST Switch
ZERO
SPAN
1.1 OVERVIEW
The Model 755A Oxygen Analyzer provides digital readout of the oxygen content of a
flowing gas sample. Oxygen is strongly paramagnetic; other common gases, with only
a few exceptions, are weakly diamagnetic.
A front panel liquid crystal display provides direct digital readout of oxygen
concentration. In addition a field-selectable voltage output is provided as standard.
An isolated current output of 0 to 20 mA or 4 to 20 mA is obtainable with the optional
Current Output Board. Current and voltage output may be utilized simultaneously if
desired.
FIGURE 1-1. MODEL 755A OXYGEN ANALYZER

INTRODUCTION
1-2 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
The basic electronic circuitry is incorporated into two master boards: The Control
Board Assembly and the Case Circuit Board Assembly (see Figure 1-2). The Control
Board has a receptacle which accepts optional circuit boards, thus permitting inclusion
of such features as current output.
1.2 OXYGEN RANGE ON FRONT PANEL DIGITAL DISPLAY
The front panel LCD (liquid crystal display) provides direct readout of oxygen
concentration from 0.00% to 100.00%.
1.3 OXYGEN RANGES FOR RECORDER READOUT
If desired, the recorder output may be set for a fullscale range of 0 to 100% oxygen.
Alternatively, a desired portion of this overall range may be selected for fullscale
presentation on the recorder. The selection is made by an appropriate combination of
scale expansion and zero suppression.
SCALE EXPANSION
Fullscale oxygen span for the recorder is switch selectable for 1%, 2%, 5%, 10%,
20%, or 100% oxygen.
ZERO SUPPRESSION
The desired zero suppression is obtained as the sum of (a) a jumper selectable fixed
value of 0%, 20%, 40%, 60% or 80% oxygen and (b) a continuously adjustable value
of 0% to 25% oxygen. Thus the electronic circuitry provides the capability of setting
the total zero suppression for any desired value from 0% up to a theoretical maximum
of 105% oxygen.
However, the maximum usable zero suppression is 99%, which is used in establishing
a range of 99% to 100%.
The effective zero suppression, in volts, may be read on the digital display by placing
the front panel TEST Switch in position 4 and the Reorder Oxygen Span Selection
Switch in 1 X gain position (i.e., 100% oxygen)
Example:
Desired oxygen range for recorder output: 99% to 100% oxygen.
Required span is 1% oxygen, obtained by jumper position.
Required zero suppression is 99% oxygen. Thus, fixed zero suppression of 80%
oxygen is selected by jumper position, and adjustable zero suppression is set for
19% oxygen.

INTRODUCTION
245364-U Rosemount Analytical April 2000 1-3
Model 755A Oxygen Analyzer
1.4 RECORDER VOLTAGE AND CURRENT OUTPUTS
VOLTAGE OUTPUTS (STANDARD)
Provided a standard is a jumper selectable voltage output of 0 to 10 mV, 0 to 100 mV,
0 to 1 V, or 0 to 5 V DC.
ISOLATED CURRENT OUTPUT (OPTION)
An isolated current output is obtainable with the optional Current Output Board, either
included with the Model 755A or added at a later date in the field.
This option provides a current output of either 0 to 20mA or 4 to 20mA for a maximum
of 850 ohms.
Refer to Section 8, Replacement Parts, for the part number of the Isolated Current
Output option.
Note
Voltage and current outputs may be used simultaneously, if desired.
1.5 AUTOMATIC PRESSURE COMPENSATION
The oxygen readout is automatically corrected for pressure variations within 3% of the
target value, which may be set anywhere within the range of -2.7 to 3.3 psig ±3 psig (-
18.6 to 22.8 kPa ±21 kPa).
1.6 ALARM (OPTION)
The analyzer has an alarm relay assembly consisting of two single-pole, double-throw
relays, one each for the ALARM 1 and ALARM 2 contacts. These relays may be used
to drive external, customer-supplied alarm and/or control devices.
1.7 CASE MOUNTING OPTIONS
The analyzer is supplied, as ordered, with hardware for one of three mounting
arrangements: Panel, wall, or pipe stanchion.
1.8 ELECTRICAL POWER OPTIONS
The analyzer is supplied, as ordered, for operation on either 120 VAC, 50/60 Hz, or
240 VAC, 50/60 Hz.

INTRODUCTION
1-4 April 2000 Rosemount Analytical 245364-UModel 755A Oxygen Analyzer
+-
+
COM
MA
MV
TB2
NO
COM
NC
RESE
NO
CO
NC
RESET
NO. 1
NO. 2
HOT
GND
N
E
U
T
H
O
T
TB1
FIGURE 1-2. MODEL 755A COMPONENTS AND ADJUSTMENTS LOCATIONS
Transformer, Power T1
(Behind TB1)
Alarm Relay Assembly
(Alarm Option)
Case Board
Case Heater
Assembly
AC Power
TB1
Detector/Magnet
Assembly
Detector/Magnet
Assembly Shock
Mount
Fuse
AC Power
Recorder Output
TB2
Fuse
Case Heater
Transducer
Location for Optional
Current Output Board
Control Board
ZERO Control
SPAN Control
Span -
Jumper Select
Recorder Output -
Jumper Select
Zero
Suppression
CAL2 Adjustment,
Pressure
Compensation
CAL1 Adjustment,
Pressure
Compensation
Zero Offset -
Jumper Select