Rosemount Manual: 755R O2 Analyzer-Rev P | Rosemount Manuals & Guides

Rosemount Analytical

ODEL

M

XYGEN ANALYZER

O

NSTRUCTION MANUAL

I

755R

N

OTICE

The information contained in this document is subject to change without notice.
Paliney No. 7™ is a trademark of J.M. Ney Co., Hartford, CT.

Viton-A
Teflon

®

is registered a trademark of E.I. duPont de Nemours and Co. Inc.

®

is a registered trademark of E.I. duPont de Nemours and Co., Inc.

Manual Part Number 748213-P
June 1997
Printed in U.S.A.

Rosemount Analytical Inc.

4125 East La Palma Avenue
Anaheim, California 92807-1802

C

ONTENTS

P

REFACE

INTENDED USE STATEMENT ..........................................................................P-1

SAFETY SUMMARY...........................................................................................P-1

SPECIFICATIONS - PERFORMANCE...............................................................P-3

SPECIFICATIONS - SAMPLE............................................................................P-3

SPECIFICATIONS - ELECTRICAL.....................................................................P-4

SPECIFICATIONS - PHYSICAL.........................................................................P-4

CUSTOMER SERVICE, TECHNICAL ASSISTANCE AND FIELD SERVICE ....P-5

RETURNING PARTS TO THE FACTORY .........................................................P-5

TRAINING ......................................................................................................P-5

DOCUMENTATION............................................................................................P-5

COMPLIANCES..................................................................................................P-6

S

ECTION

1.1 DESCRIPTION ..........................................................................................1-1

1.2 RECORDER OUTPUT RANGE ................................................................1-2

1.3 MOUNTING ..............................................................................................1-2

1.4 ISOLATED CURRENT OUTPUT ..............................................................1-2

1.5 ALARM OPTION ........................................................................................1-2

1.6 ELECTRICAL OPTIONS............................................................................1-2

1.7 REMOTE RANGE CHANGE OPTION.......................................................1-2

S

ECTION

2.1 FACILITY PREPARATION ........................................................................2-1

1. I

2. I

2.1.1 Installation Drawings......................................................................2-1

2.1.2 Electrical Interconnection Diagram.................................................2-1

2.1.3 Flow Diagram.................................................................................2-1

NTRODUCTION

NSTALLATION

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

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ONTENTS

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ECTION

2.2 CALIBRATION GAS REQUIREMENTS....................................................2-2

2.3 SAMPLE HANDLING ...............................................................................2-3

2.4 ELECTRICAL CONNECTIONS.................................................................2-7

2. (

2.1.4 Location and Mounting..................................................................2-1

2.2.1 Zero Standard Gas........................................................................2-3

2.2.2 Span Standard Gas.......................................................................2-3

2.3.1 Sample Temperature Requirements .......................................... 2-4

2.3.2 Sample Pressure Requirements: General..................................2-4

2.3.3 Normal Operation at Positive Gauge Pressures.........................2-4

2.3.4 Operation at Negative Gauge Pressures....................................2-5

2.3.5 Sample Flow Rate......................................................................2-5

2.3.6 Materials in Contact with Sample...............................................2-6

2.3.7 Corrosive Gases.........................................................................2-6

2.3.8 Leak Test....................................................................................2-6

2.4.1 Line Power Connections.............................................................2-7

2.4.2 Recorder Output Selection and Cable Connections...................2-8

2.4.3 Output Connections and Initial Setup for Dual Alarm Option......2-10

CONTINUED

2.4.2.1 Potentiometric Output.................................................2-8

2.4.2.2 Isolated Current Output (Optional)..............................2-9

)

2.5 REMOTE RANGE CHANGE OPTION......................................................2-14

S

ECTION

3.1 OVERVIEW............................................................................................... 3-1

3.2 OPERATING RANGE SELECTION..........................................................3-1

3.3 STARTUP PROCEDURE..........................................................................3-1

3.4 CALIBRATION ..........................................................................................3-1

3.5 COMPENSATION FOR COMPOSITION OF BACKGROUND GAS........3-2

3.6 SELECTION OF SETPOINTS AND DEADBAND ON ALARM OPTION..3-7

3.7 CURRENT OUTPUT BOARD (OPTION) .................................................3-7

S

ECTION

4.1 ROUTINE OPERATION............................................................................4-1

4.2 EFFECT OF BAROMETRIC PRESSURE CHANGES ON INSTRUMENT

3. S

3.4.1 Calibration with Zero and Span Standard Gases.......................3-2

3.5.1 Oxygen Equivalent Value of Gases............................................3-4

3.5.2 Computing Adjusted Settings for Zero and Span Controls.........3-5

4. O

TARTUP AND CALIBRATION

PERATION

READOUT ....................................................................................4-1

4.3 CALIBRATION FREQUENCY...................................................................4-2

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

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ONTENTS

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ECTION

5.1 PRINCIPLES OF OPERATION .................................................................5-1

5.2 VARIABLES INFLUENCING PARAMAGNETIC OXYGEN

5.3 ELECTRONIC CIRCUITRY .......................................................................5-4

S

ECTION

6.1 CIRCUIT OPERATION..............................................................................6-1

6.2 ±15 VDC 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 .......................................6-8

5. T

5.2.1 Pressure Effects..........................................................................5-2

5.3.1 Detector/Magnet Assembly.........................................................5-4

5.3.2 Control Board and Associated Circuitry......................................5-6

5.3.3 Power Supply Board Assembly...................................................5-7

5.3.4 Isolated Current Output Board (Optional)....................................5-8

6. C

HEORY

MEASUREMENTS........................................................................5-2

IRCUIT ANALYSIS

6.7 BUFFER AMPLIFIERS U8, U10 WITH ASSOCIATED ANTICIPATION

FUNCTION....................................................................................6-11

6.8 DIGITAL OUTPUT CIRCUIT.....................................................................6-11

6.9 ANALOG OUTPUT CIRCUITS FOR RECORDER ALARMS....................6-12

6.9.1 First Stage Amplifier....................................................................6-12

6.9.2 Second Stage Amplifier...............................................................6-12

S

ECTION

7.1 INITIAL CHECKOUT WITH STANDARD GASES....................................7-1

7.2 HEATING CIRCUITS................................................................................7-3

7.3 DETECTOR CHECK.................................................................................7-4

7.4 REPLACEMENT OF DETECTOR/MAGNET ASSEMBLY

7. S

7.1.1 Control Board Checkout..............................................................7-2

7.2.1 Case Heater Control Circuit ........................................................7-3

7.2.2 Detector/Magnet Heating Circuit.................................................7-3

7.3.1 Source Lamp ...............................................................................7-5

7.3.2 Photocells....................................................................................7-6

7.3.3 Suspension .................................................................................7-6

ERVICE AND MAINTENANCE

COMPONENTS.............................................................................7-6

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

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ONTENTS

S

ECTION

7.5 CONTROL BOARD SETUP.....................................................................7-9

SECTION

8.1 CIRCUIT BOARD REPLACEMENT POLICY...........................................8-1

8.2 SELECTED REPLACEMENT PARTS .....................................................8-1

ENERAL PRECAUTIONS FOR HANDLING

G

ARRANTY

W

IELD SERVICE AND REPAIR FACILITIES

F

7. (

7.4.1 Source Lamp..............................................................................7-6

7.4.2 Photocell.....................................................................................7-6

7.4.3 Detector......................................................................................7-8

8.

CONTINUED

REPLACEMENT PARTS

)

TORING HIGH PRESSURE CYLINDERS

& S

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

F

IGURES

1-1 Model 755R Oxygen Analyzer..................................................................1-1

2-1 Interconnection of Typical Gas Manifold to Model 755R..........................2-3

2-2 Model 755R Rear Panel...........................................................................2-7

2-3 Connections for Potentiometric Recorder with Non-Standard Span.........2-8

2-4 Model 755R Connected to Several Current Activated Output Devices.....2-9

2-5 Relay Terminal Connections for Typical Fail Safe Applications................2-10

2-6 Typical Alarm Settings..............................................................................2-13

2-7 Alarm Relay Assembly Schematic Diagram.............................................2-13

3-1 Control Board Adjustments.......................................................................3-3

3-2 Dial Settings for Alarm Setpoint Adjustments...........................................3-8

5-1 Functional Diagram of 755R Paramagnetic O2 Measurement System......5-3

5-2 Spherical Body in Non-Uniform Magnetic Field........................................5-4

5-3 Detector/Magnet Assembly.......................................................................5-5

6-1 Two-Comparator OR Circuit.....................................................................6-3

6-2 Case Heater Control Circuit......................................................................6-3

6-3 Ramp Generator Circuit............................................................................6-4

6-4 Detector Heater Control Circuit.................................................................6-7

6-5 Detector Light Source Control Circuit.......................................................6-8

6-6 Detector with First Stage Amplifier............................................................6-10

6-7 Buffer, Anticipation, and Digital Output Circuits........................................6-11

6-8 Simplified Analog Recorder Output Circuit...............................................6-13

7-1 Detector/Magnet Assembly.......................................................................7-4

7-2 Pin/Lead Removal....................................................................................7-5

7-3 Detector Optical Bench.............................................................................7-5

7-4 Lamp Replacement ..................................................................................7-7

C

ONTENTS

T

ABLES

3-1 Calibration Range for Various Zero-Based Operating Ranges.................3-4

3-2 Oxygen Equivalents of Common Gases...................................................3-6

D

RAWINGS (LOCATED IN REAR OF MANUAL

617186 Schematic Diagram, Power Supply Board
620434 Schematic Diagram, Isolated V/I Board
646090 Schematic Diagram, Remote Range Board
652826 Schematic Diagram, Control Board
654014 Pictorial Wiring Diagram, Model 755R
654015 Installation Drawing, Model 755R
656081 Instructions, Remote Range Selection

748213-P Rosemount Analytical June 1997

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Model 755R Oxygen Analyzer

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C

ONTENTS

N

OTES

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

P

REFACE

I

NTENDED USE STATEMENT

The Model 755R 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.

S

AFETY 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
755R Analyzer should be thoroughly familiar with and strictly follow the instructions in
this manual.

Save these instructions.

DANGER

personal injury, death, or substantial property damage if the warning is ignored

WARNING

personal injury, death, or substantial property damage if the warning is ignored.

CAUTION

personal injury or property damage if the warning is ignored.

NOTE

important but not hazard-related.

is used to indicate the presence of a hazard which

is used to indicate the presence of a hazard which

is used to indicate the presence of a hazard which

is used to indicate installation, operation, or maintenance information which is

will

will

can

or

cause

cause

can

cause

severe

severe

minor

WARNING: ELECTRICAL SHOCK HAZARD

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.

Optional alarm switching relay contacts wired to separate power sources must
be disconnected before servicing.

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

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WARNING: POSSIBLE EXPLOSION HAZARD

This analyzer is of a type capable of analysis of sample gases which may be
flammable. If used for analysis of such gases, internal leakage of sample could
result in an explosion causing death, personal injury, or property damage. Do
not use this analyzer on flammable samples. Use explosion-proof version
instruments for analysis of flammable samples.

WARNING: PARTS INTEGRITY

Tampering or unauthorized substitution of components may adversely affect
safety of this product. Use only factory documented components for repair

CAUTION: HIGH PRESSURE GAS CYLINDERS

This analyzer requires periodic calibration with known zero and standard gases.
Refer to Sections 2.2 and 2.3. See also General Precautions for Handling and
Storing High Pressure Cylinders, following Section 7.

This instrument’s internal pullout chassis is equipped with a safety stop latch
located on the left side of the chassis.

When extracting the chassis, verify that the safety latch is in its proper (counter­clockwise) orientation.

If access to the rear of the chassis is required, the safety stop may be
overridden by lifting the latch; however, further extraction must be done very
carefully to insure the chassis does not fall out of its enclosure.

CAUTION: TOPPLI N G HA ZARD

If the instrument is located on top of a table or bench near the edge, and the
chassis is extracted, it must be supported to prevent toppling.

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

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REFACE

S

PECIFICATIONS1

O

PERATING RANGE (STANDARD

0 to 5, 0 to 10, 0 to 25, 0 to 50, and 0 to 100% oxygen

O

PERATING RANGE (OPTIONAL

0 to 1, 0 to 2.5, 0 to 5, 0 to 10, 0 to 25, 0 to 50, and 0 to 100% oxygen

R

ESPONSE TIME

90% of fullscale, 20 seconds

R

EPRODUCIBILITY

0.01% oxygen or ±1% of fullscale, whichever is greater

A

MBIENT TEMPERATURE LIMITS

32°F (0°C) to 113°F (45°C)

Z

ERO DRIFT

1% fullscale per 24 hours, provided that ambient temperature does not

±

change by more than 20°F (11.1°C)

2.5% of fullscale per 24 hours with ambient temperature change over

±

entire range

S

PAN DRIFT

1% fullscale per 24 hours, provided that ambient temperature does not

±

change by more than 20°F (11.1°C)

2.5% of fullscale per 24 hours with ambient temperature change over

±

entire range

- P

ERFORMANCE

)

)

S

PECIFICATIONS

D

RYNESS

– S

AMPLE

Sample dewpoint below 110°F (43°C), sample free of entrained liquids.

T

EMPERATURE LIMITS

50°F (10°C) to 150°F (65°C)

O

PERATING PRESSURE

Maximum: 10 psig (68.9 kPa)
Minimum: 5 psig vacuum (34.5 kPa vacuum)

F

LOW RATE

50 cc/min. to 500 cc/min.
Recommended 250 ±20 cc/min.

M

ATERIALS IN CONTACT WITH SAMPLE

Glass, 316 stainless steel, titanium, Paliney No. 7, epoxy resin, Viton-A,
platinum, nickel, and MgF2

1

Performance specifications are measured at recorder output and are based on constant sample pressure and deviation

from set flow held to within 10% or 20 cc/min., whichever is smaller.

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

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S

PECIFICATIONS

S

UPPLY VOLTAGE AND FREQUENCY

S

TANDARD

115 VAC ±10%, 50/60 Hz

O

PTIONAL

230 VAC ±10%, 50/60 Hz

P

OWER CONSUMPTION

300 watts maximum, 75 watts nominal

O

UTPUTS STANDARD

Field selectable voltage output of 0 to 10 mV, 0 to 100 mV, 0 to 1 V, or 0 to
5 VDC

O

UTPUTS OPTIONAL

Isolated current output of 0 to 20 mA or 4 to 20 mA is obtainable through
plug-in of optional circuit board

O

PTIONAL ALARMS

High and low, independently adjustable alarms. Form C contact ratings.

A

LARM CONTACT RATINGS

5 A, 240 VAC resistive

:

:

- E

LECTRICAL

5 A, 120 VAC resistive
5 A, 28 VDC resistive

S

ETPOINT

Adjustable from 1% to 100% fullscale

D

EADBAND

Adjustable from 1% to 20% fullscale. Factory set to 10% of fullscale.

S

PECIFICATIONS

M

OUNTING

19 inch rack (IEC 297-1, 1986)

C

ASE CLASSIFICATION

General Purpose

W

EIGHT

46 lbs. (21 kg)

D

IMENSIONS

19.0 x 8.7 x 19.2 inches (482.2 x 221 x 487 mm) W x H x D

- P

HYSICAL

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

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REFACE

C

USTOMER SERVICE

For order administration, replacement Parts, application assistance, on-site or factory
repair, service or maintenance contract information, contact:

R

ETURNING 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:

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.

Model Number, Serial Number, and Purchase Order Number or Sales Order

, T

ECHNICAL ASSIST ANCE AND FIELD SERVICE

Rosemount Analytical Inc.

Process Analytical Division

Customer Service Center

1-800-433-6076

Return to:

Rosemount Analytical Inc.

4125 East La Palma Avenue

Anaheim, California 92807-1802

T

RAINING

A comprehensive Factory Training Program of operator and service classes is
available. For a copy of the
the Technical Services Department at:

D

OCUMENTATION

The following Model 755R Oxygen Analyzer instruction materials are available.
Contact Customer Service or the local representative to order.

748213 Instruction Manual (this document)

Current Operator and Service Training Schedule

Rosemount Analytical Inc.

Phone: [phone]

FAX: [phone]

contact

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

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C

OMPLIANCES

This product satisfies all obligations of all relevant standards of the EMC framework in
Australia and New Zealand.

9

N

6

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June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

I

NTRODUCTION

1

1.1 DESCRIPTION

The Model 755R Oxygen Analyzer provides continuous readout of the oxyg en content of
a flowing gas sample. The determination is based on measurement of the magnetic
susceptibility of the sample gas. Oxygen is strongly paramagnetic while most other
common gases are weakly diamagnetic.

The instrument provides direct readout of 0 to 100% oxygen concentration on a front
panel digital display. 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 through
plug-in of an optional circuit board. Current and voltage outputs may be utilized
simultaneously if desired. An alarm option is also available by way of a relay assembly
that mounts at the rear of the case with a cable that plugs into the Control Board.
Customer connections are available on thi s assembl y .

The basic electronic circuitry is incorporated into two master boards designated the
Control Board assembly and the Power Supply Board assembly. The Control Board has
receptacles that accept optional plug-in curr ent output boar d and alar m features.

IGURE

F

1-1. M

ODEL

Digita l Di s play

%

O

2

SPANZERO

Rosemount Anal ytical

Zero Control Span Control

755R O

XYGEN ANALYZER

Model 755R

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

1-1

I

NTRODUCTION

1.2 RECORDER OUTPUT RANGES

Seven zero-based ranges are available with the Model 755R: 0 to 1%, 0 to 2.5%, 0 to
5%, 0 to 10%, 0 to 25%, 0 to 50%, and 0 to 100%. Each range is jumper selectable.

1.3 MOUNTING

The Model 755R is a rack-mounted instrument, standard for a 19-inch relay rack (Refer
to IEC Standard, Publication 297-1, 1986).

1.4 ISOLATED CURRENT OUTPUT OPTION

An isolated current output is obtainable by using an optional current output board, either
during factory assembly or subsequently in the field. The board provides ranges of 0 to
20 or 4 to 20 mA into a maximum resistiv e l oad of 1000 ohms.

1.5 ALARM OPTION

The alarm option contains:

An alarm circuit incorporating two comparator amplifiers, one each for the

•

ALARM 1 and ALARM 2 functions. Each amplifier has associated setpoint and
deadband adjustments. Setpoint is adjustable from 1% to 100% of fullscale.
Deadband is adjustable from 1% to 20% of fullscale.

An alarm relay assembly, containing 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.

1.6 ELECTRICAL OPTIONS

The analyzer is supplied, as ordered, for operation on either 115 VAC, 50/60 Hz or 230
VAC, 50/60 Hz.

1.7 REMOTE RANGE CHANGE OPTION

This option allows the customer to remotely control the recorder scaling. It disables
the internal recorder fullscale range select without affecting the front panel display.

1-2

June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

I

NSTALLATION

2.1 FACILITY PREPARATION

Observe all precautions given in this section when installing the instrument.

2

2.1.1 I

2.1.2 E

2.1.3 F

2.1.4 L

NSTALLATION DRAWINGS

For outline and mounting dimensions, gas connections, and other installation
information, refer to Installation Drawing 654015 at the back of this manual.

LECTRICAL INTERCONNECTION DIAGRAM

Electrical interconnection is also shown in drawing 654015. Refer also to Section 2.4.

LOW DIAGRAM

The flow diagram of Figure 2-1 shows connection of a typical gas selector manifold to
the Model 755R.

OCATION AND MOUNTING

Install the Model 755R only in a non-hazardous, weather-protected area. Permissible
ambient temperature range is 32°F to 113°F (0°C to 45°C). Avoid mounting where
ambient temperature may exceed the allowable maximum.

Magnetic susceptibilities and partial pressures of gases vary with temperature. In the
Model 755R, temperature-induced readout error is avoided by control of temperatures
in the following areas:

1. Interior of the analyzer is maintained at 140°F (60°C) by an electrically controlled

heater and associated fan.

2. Immediately downstream from the inlet port, prior to entry into the detector, the

sample is preheated by passage through a coil maintained at approximately the
same temperature as the detector (See Figure 5-3, A).

3. The detector is maintained at a controlled temperature of 150°F (66°C).

Also, avoid excessive vibration. To minimize vibration effects, the detector/magnet
assembly is contained in a shock-mounted compartment.

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

2-1

M

ODEL

755R O

XYGEN ANALYZER

WARNING: POSSIBLE EXPLOSION HAZARD

This analyzer is of a type capable of analysis of sample gases which may be
flammable. If used for analysis of such gases, internal leakage of sample could
result in an explosion causing death, personal injury, or property damage. Do
not use this analyzer on flammable samples. Use explosion-proof version
instruments for analysis of flammable samples.

Use reasonable precautions to avoid excessive vibration. In making electrical
connections, do not allow any cable to touch the shock-mounted detector assembly or
the associated internal sample inlet and outlet tubing. This precaution ensures against
possible transmission of mechanical vibration through the cable to the detector, which
could cause noisy readout.

2.2 CALIBRATION GAS REQUIREMENTS

WARNING: HIGH PRESSURE GAS CYLINDERS

Calibration gas cylinders are under pressure. Mishandling of gas cylinders
could result in death, injury, or property damage. Handle and store cylinders
with extreme caution and in accordance with the manufacturer’s instructions.
Refer to GENERAL PRECAUTIONS FOR HANDLING & STORING HIGH
PRESSURE CYLINDERS at the rear of this manual.

Analyzer calibration consists of establishing a zero calibration point and a span
calibration point.

Zero calibration is performed on the range that will be used during sample analysis. In
some applications, however, it may be desirable to perform span calibration on a
range of higher sensitivity (i.e., more narrow span) and then jumper to the desired
operating range. For example, if the operating range is to be 0 to 50% oxygen, span
calibration may be performed on the 0 to 25% range to permit use of air as the span
standard gas.

Recommendations on calibration gases for various operating ranges are tabulated in
Table 3-1 and are explained in Sections 2.2.1 and 2.2.2.

Each standard gas should be supplied from a cylinder equipped with dual-stage, metal
diaphragm type pressure regulator, with output pressure adjustable from 0 to 50 psig
(0 to 345 kPa).

Instrument response to most non-oxygen sample components is comparatively slight,
but is not in all cases negligible. During initial installation of an instrument in a given
application, effects of the background gas should be calculated to determine if any
correction is required (See Section 3.4).

2-2

Rosemount Analytical

June 1997

748213-P

I

NSTALLATION

2.2.1 Z

ERO STANDA RD GAS

In the preferred calibration method, described in Section 3.4.1, a suitable zero
standard gas is used to establish a calibration point at or near the lower range limit.
Composition of the zero standard normally requires an oxygen-free zero gas, typically
nitrogen.

2.2.2 S

PAN STANDA RD GAS

A suitable span standard gas is required to establish a calibration point at or near the
upper range limit. If this range limit is 21% or 25% oxygen, the usual span standard
gas is air (20.93% oxygen).

2.3 SAMPLE HANDLING

Basic requirements for sample handling are:

1. A 2-micron particulate filter, inserted into the sample line immediately upstream

from the analyzer inlet.

2. Provision for pressurizing the sample gas to provide flow through the analyzer.

3. Provision for selecting sample, zero standard, or span standard gas for admission

to the analyzer, and for measuring the flow of the selected gas.

Sample In

Zero
Standard
Gas

Span
Standard
Gas

Needle
Valves

Two Micron

Flowmeter

Filter

Model 755R

Oxygen Analyzer

To Vent

IGURE

F

748213-P Rosemount Analytical June 1997

2-1. I

NTERCONNECTION OF TYPICAL GAS MANIFOLD TO MODEL

755R

Model 755R Oxygen Analyzer

2-3

I

NSTALLATION

2.3.1 S

AMPLE TEMPERATURE REQUIREMENTS

Sample temperature at the analyzer inlet should be in the range of 50°F to 150°F
(10°C to 66°C).

Normally, however, a maximum entry temperature of 110°F (43°C) is recommended
so that the sample temperature will rise during passage of the sample through the
analyzer. This precaution prevents cooling of the sample and possible
analyzer-damaging condensation. With a thoroughly dry sample, entry temperature
can be as high as 150°F (66°C) without affecting readout accuracy.

2.3.2 S

AMPLE PRESSURE REQUIREMENTS

: G

ENERAL

Operating pressure limits are as follows: maximum, 10 psig (68.9 kPa); minimum, 5
psig vacuum (34.5 kPa vacuum).

CAUTION: RANGE LIMITATIONS

Operation outside the specified pressure limits may damage the detector, and
will void the warranty.

The basic rule for pressure of sample and standard gases supplied to the inlet is to
calibrate the analyzer at the same pressure that will be used during subsequent
operation, and to maintain this pressure during operation. The arrangement required
to obtain appropriate pressure control will depend on the application. When inputting
sample or calibration gases, use the same pressure that will be used during
subsequent operation. Refer to Section 2.3.3, Normal Operation at Positive Gauge
Pressures, or Section 2.3.4, Operation at Negative Gauge Pressures.

2.3.3 N

ORMAL OPERATION AT POSITIVE GAUGE PRESSURES

Normally, the sample is supplied to the analyzer inlet at a positive gauge pressure in
the range of 0 to 10 psig (0 to 68.9 kPa).

CAUTION: HIGH PRESSURE GAS

Pressure surges in excess of 10 psig during admission of sample or standard
gases can damage the detector.

Maximum permissible operating pressure is 10 psig (68.9 kPa). To ensure against
over-pressurization, insert a pressure relief valve into the sample inlet line. In addition,

2-4

June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

I

NSTALLATION

a check valve should be placed in the vent line if the analyzer is connected to a
manifold associated with a flare or other outlet that is not at atmospheric pressure. If
the detector is over-pressurized, damage will result.

The analyzer exhaust port is commonly vented directly to the atmosphere. Any
change in barometric pressure results in a directly proportional change in the indicated
percentage of oxygen.

Example:

Range, 0% to 5% O

2.

Barometric pressure change after calibration, 1%.

2

Instrument reading, 5% O
Readout error = 0.01 x 5% O
Fullscale span is 5% O

.

2

= 0.05% O2.

2.

Therefore, the 0.05% O2 error is equal to 1% of fullscale.

Thus, if the exhaust is vented to the atmosphere, the pressure effect must be taken
into consideration. This may be accomplished in various ways, including manual
computation and computer correction of data.

2.3.4 O

PERATION AT NEGATIVE GAUGE PRESSURES

Operation at negative gauge pressures is not normally recommended, but may be
used in certain special applications. A suction pump is connected to the analyzer
exhaust port to draw sample into the inlet and through the analyzer. Such operation
necessitates special precautions to ensure accurate readout. First is the basic
consideration of supplying the standard gases to the analyzer at the same pressure
that will be used for the sample during subsequent operation. In addition, any leakage
in the sample handling system will result in decreased readout accuracy as compared
with operation at atmospheric pressure.

The minimum permissible operating pressure is 5 psig vacuum (34.5 kPa vacuum).
Operation of the analyzer below this limit may damage the detector, and will void the
warranty.

2.3.5 S

AMPLE FLOW RATE

Operating limits for sample flow rate are as follows: minimum, 50 cc/min; maximum,
500 cc/min. A flow rate of less than 50 cc/min is too weak to sweep out the detector
and associated flow system efficiently. Incoming sample may mix with earlier sample,
causing an averaging or damping effect. Too rapid a flow will cause back pressure
that will affect the readout accuracy. The optimum flow rate is between 200 and 300
cc/min.

Deviation from the set flow should be held to within 10% or 20 cc/min, whichever is

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

2-5

I

NSTALLATION

smaller. If deviation is held to within these parameters and operating pressure remains
constant, zero and span drift will remain within specification limits.

The analyzer should be installed near the sample source to minimize transport time.
Otherwise, time lag may be appreciable. For example, assume that sample is supplied
to the analyzer via a 100-foot (30.5 m) length of 1/4-inch (6.35 mm) tubing. With a flow
rate of 100 cc/min, sample transport time is approximately 6 minutes.

Sample transport time may be reduced by piping a greater flow than is required to the
analyzer, and then routing only the appropriate portion of the total flow through the
analyzer. The unused portion of the sample may be returned to the stream or
discarded.

2.3.6 M

ATERIALS IN CONTACT WITH SAMPLE

Within the Model 755R, the following materials are exposed to the sample: 316
stainless steel, glass, titanium, Paliney No.7, epoxy resin, Viton-A, platinum, nickel
and MgF2 coating on mirror.

2.3.7 C

ORROSIVE GASES

In applications where the sample stream contains corrosive gases, a complete drying
of the sample is desirable, as most of these gases are practically inert when totally
dry. For corrosive applications consult the factory.

2.3.8 L

EAK TEST

WARNING: POSSIBLE TOXIC OR CORROSIVE HAZARD

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.

2-6

Internal leaks resulting from failure to observe these precautions could result in
personal injury or property damage.

For proper operation and safety, system leakage must be corrected, particularly
before introduction of toxic or corrosive samples and/or application of electrical power.

To check system for leaks, liberally cover all fittings, seals, and other possible sources
of leakage with suitable leak test liquid such as SNOOP (P/N 837801). Check for
leak-indicative bubbling or foaming. Leaks that are inaccessible to SNOOP application
could evade detection by this method.

June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer

A B I C D E

L1/HOT

L2/NEUT

CUR VOLT
OUTPUT OUTPU T

+ - G + -

GND

I

NSTALLATION

IGURE

F

(Rear terminal cover remo ved f o r clarity)
A. Sample outlet. 1/4” O.D. tube fitting.

B. Sample Inlet. 1/4” O.D. tube fitting.
C. 5/8” diameter hole for optional Dual Alarm Cable. Cable suppl i ed by customer, mi ni mum 24 AWG.
D. 5/8” diameter hole fit ted with liquid-tight gland for Recorder Out put Cable. Cable supplied by customer, 2
conductor, minimum 24 AWG.
E. 13/16” diameter hole for Power Cable. Cable supplied by custom er, 3 conductor, minimum 18 AWG.
F. TB1: Customer hook-up f or P ower.
G. TB2: Customer hook-up for Recorder Output.
H. Optional Dual Alarm c onnections.
I. Connections for Opti onal Remote Range Change.

2-2. M

ODEL

755R R

EAR PANEL

H G H

2.4 ELECTRICAL CONNECTIONS

WARNING: ELECTRICAL SHOCK HAZARD

For safety and proper performance, this instrument must be connected to a
properly grounded three-wire source of supply.

Cable connections for AC power, recorder output, and alarm output are shown in
Installation Drawing, 654015, and are explained in the following sections.

2.4.1 L

INE POWER CONNECTION

The analyzer is supplied, as ordered, for operation on 115 VAC or 230 VAC, 50/60 Hz.
Ensure that the power source conforms to the requirements of the individual
instrument, as noted on the name-rating plate.

Electrical power is supplied to the analyzer via a customer-supplied three-conductor

748213-P Rosemount Analytical June 1997

Model 755R Oxygen Analyzer

2-7

I

I

(Verif

NSTALLATION

cable, type SJT, minimum wire size 18 AWG. Route power cable through conduit and
into appropriate opening in the instrument case. Connect power leads to HOT, NEUT,
and GND terminals on the I/O board. Connect analyzer to power source via an
external fuse or breaker, in accordance with local codes. Do not draw power for
associated equipment from the analyzer power cable (Refer to Figure 2-3).

IGURE

F

2-3. C

S

755R

Analyzer

Voltage Divider
(Customer Supplied)

Position of Recorder Output

Selector Plug

10 mV 1K
100 mV 10K
1 V 100K
5 V 2K

Minimum Permissible

Resistance for R1 + R2

ONNECTIONS FOR POTENTIOMETRIC RECORDER WITH NON-STANDARD

PAN

Potentiometric

Recorder

nput

Terminals

y polarity

is correct)

(ohms)

If the analyzer is mounted in a protected rack or cabinet or on a bench, an accessory
kit (P/N 654008) is available which provides a 10-foot North American power cord set
and a liquid-tight feed through gland for the power cable hole. The kit also contains
four enclosure support feet for bench top use.

2.4.2 R

ECORDER OUTPUT SELECTION AND CABLE CONNECTIONS

If a recorder, controller, or other output device is used, connect it to the analyzer via a
number 22 or number 24 AWG two-conductor shielded cable. Route the cable into the
case through the liquid-tight feed through gland in the Recorder Output opening (See
Installation Drawing, 654015). Connect the shield only at the recorder end or the
analyzer end, not to both at the same time because a ground loop may occur.

Note:
Route recorder cable through a separate cable gland (P/N 899329) or conduit not

with power cable or alarm output cable. Cable connections and output selection
for potentiometric and current-actuated devices are explained below.

2.4.2.1 P

OTENTIOMETRIC OUTPUT

1. Insert RECORDER OUTPUT Selector Plug (See Figure 3-1) in position appropriate
to the desired output: 10 mV, 100 mV, 1V or 5V.

2. Connect leads of shielded recorder cable to “REC OUT +” and “-” terminals on the

2-8

June 1997 Rosemount Analytical 748213-PModel 755R Oxygen Analyzer