Rosemount 755A Instruction Manual
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Rosemount 755A Instruction Manual

Rosemount 755A Instruction Manual

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Rosemount Analytical
M
755A
ODEL
O
A
XYGEN
NALYZER
I
M
NSTRUCTION
ANUAL
245364-U

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  • Page 1 Rosemount Analytical 755A ODEL XYGEN NALYZER NSTRUCTION ANUAL 245364-U...
  • Page 2 Teflon® is a registered trademark of E.I. duPont de Nemours and Co., Inc. SNOOP® is a registered trademark of NUPRO Co. Manual Part Number 245364-U April 2000 Printed in U.S.A. Rosemount Analytical Inc. 4125 East La Palma Avenue Anaheim, California 92807-1802...

  • Page 3: Table Of Contents

    RECORDER VOLTAGE AND CURRENT OUTPUTS ......1-3 AUTOMATIC PRESSURE COMPENSATION ..........1-3 ALARM (OPTION) ..................1-3 CASE MOUNTING OPTIONS ..............1-3 ELECTRICAL POWER OPTIONS ............1-3 2. U ECTION NPACKING AND NSTALLATION UNPACKING ....................2-1 LOCATION ....................2-1 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 4 Computing Adjusted Settings for Zero and Span Controls ..3-11 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 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 5 DETECTOR LIGHT SOURCE CONTROL CIRCUIT ........6-7 DETECTOR WITH FIRST STAGE AMPLIFIER AND PRESSURE COMPENSATION CIRCUITS ............6-8 BUFFER AMPLIFIERS U10 AND ASSOCIATED ANTICIPATION FUNCTION..................6-12 DIGITAL OUTPUT CIRCUIT..............6-12 ANALOG OUTPUT CIRCUITS FOR RECORDER AND ALARMS ...6-13 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 6 Detector/Magnet Heating Circuit ..........7-9 8. R ECTION EPLACEMENT ARTS CIRCUIT BOARD REPLACEMENT POLICY ........... 8-1 SELECTED REPLACEMENT PARTS ............. 8-1 ENERAL RECAUTIONS TORING AND ANDLING RESSURE YLINDERS ARRANTY IELD ERVICE AND EPAIR ACILITIES Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 7 ONTENTS IGURES Model 755A Oxygen Analyzer ..............1-1 Analyzer Components and Adjustments Locations ........1-4 Electrical Connections ................2-3 Control Board ...................2-4 Connections for Potentiometric Recorder with Non-Standard Span ..2-4 Analyzer Connected to Drive Several Current-Activated Output Devices ..................2-5 Typical Alarm Settings................2-7 Relay Terminal Connections for Typical Fail-Safe Application ....2-7 Connection of Typical Gas Selector Panel to Analyzer ......2-9...
  • Page 8 ONTENTS RAWINGS 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...

  • Page 9: Preface

    NTENDED TATEMENT 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.
  • Page 10 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. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...

  • Page 11: Specifications - General

    Zero 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. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 12: Specifications - Electrical

    Deviation 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. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...

  • Page 13: Specifications - Physical

    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. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 14: Customer Service, Technical Assistance And Field Service

    Technical Services Department at: Rosemount Analytical Inc. Phone: 1-714-986-7600 FAX: 1-714-577-8006 OCUMENTATION The following Model 755A Oxygen Analyzer instruction materials are available. Contact Customer Service or the local representative to order. 245364 Instruction Manual (this document) Model 755A Oxygen Analyzer April 2000...

  • Page 15: Compliances

    REFACE OMPLIANCES 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.
  • Page 16 REFACE OTES Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 17: Introduction

    NTRODUCTION 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.

  • Page 18: Oxygen Range On Front Panel Digital Display

    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. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 19: Recorder Voltage And Current Outputs

    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.
  • Page 20 RESET Fuse Case Heater Fuse AC Power AC Power Detector/Magnet Assembly Shock Mount Transducer Detector/Magnet Transformer, Power T1 Assembly (Behind TB1) 1-2. M 755A C IGURE ODEL OMPONENTS AND DJUSTMENTS OCATIONS Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 21: Section 2. Unpacking And Installation

    For safety and proper performance this instrument must be connected to a properly grounded three-wire source of power. Note Refer to Installation Drawing 642349 at the rear of this manual for recommended cable conduit openings. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 22: Electrical Connections

    Route the cable through conduit to the analyzer and into the case through the appropriate opening shown in Installation Drawing 642349. Connect the shield only at the recorder or computer, if used. Cable connections and output selection for potentiometric and current actuated Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 23: Electrical Connections

    Optional Alarm Kit NO. 1 RESET NO. 2 + - + mV Recorder RESET mA Recorder Power Connections (see below) Jumpers Jumper 120 VAC CONFIGURATION 240 VAC CONFIGURATION 2-1. E IGURE LECTRICAL ONNECTIONS 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 24: Control Board

    Position of Recorder Output Minimum Permissible Selector Plug Resistance for R1 + R2 10 mV 1K Ohm 100 mV 10K Ohm 100K Ohm 2K Ohm 2-3. C IGURE ONNECTIONS FOR OTENTIOMETRIC ECORDER WITH TANDARD Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 25: Output Connections For Dual Alarm Option

    2. If the alarm contacts are connected to any device that produces radio frequency interference (RFI), it should be arc-suppressed. Rosemount Analytical Arc Suppression (PN 858728) is recommended. 3. If possible, the analyzer should operate on a different AC power source to avoid RFI. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 26 It is important that, for fail-safe applications, the user understand wheat circuit conditions are desired in the event of power failure and the resultant relay de- energization. Relay contacts should then be connected accordingly. Refer to Figure 2-6. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 27 Limit, Valve Fail-Safe Higher High Alarm 115 VAC Alarm Bell Indicator, 115 VAC or Lamp Fail-Safe RESET RESET No. 2 No. 2 2-6. R IGURE ELAY ERMINAL ONNECTIONS FOR YPICAL PPLICATION 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 28: Calibration

    (10°C to 66°C). With a thoroughly dry sample, entry temperature can be as high as 150°F (66°C) without affecting readout accuracy. Normally, a maximum entry temperature of 110°F (43°C) is recommended so that the sample temperature will rise Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 29: Sample Pressure Requirements: General

    Needle Valves Model 755A Oxygen Analyzer Sample In Two Micron To Vent Filter Downscale Flowmeter Standard Upscale Standard 2-7. C 755A IGURE ONNECTION OF YPICAL ELECTOR ANEL TO ODEL XYGEN NALYZER 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 30: Normal Operation At Positive Gauge Pressures

    Bypass Flow - Preferably the analyzer should be installed near the sample source to minimize transport time. Otherwise the 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 2-10 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 31: Corrosive Gases

    Flow reading should drop to zero. If not, system is leaking. Leaks must be corrected before introduction of flammable sample and/or application of electrical power. Liberally cover all fittings, seals, and other possible sources of 245364-U Rosemount Analytical April 2000 2-11 Model 755A Oxygen Analyzer...

  • Page 32: Purge Kit (Optional)

    2.8 PURGE KIT (OPTIONAL) The Purge Kit (PN 643108) is designed to equip the Model 755A with Type Z Air Purge per National Fire Protection Association Standard NFPA496-1986, Chapter 2...

  • Page 33: Installation Of Purge Kit (Optional)

    Inlet Fitting Purge Purge Supply Supply Flow Pressure Indicator Indicator or Alarm 645835 Purge Outlet Fitting Components in dashed line are supplied by customer. 2-8. I IGURE NSTALLATION OF URGE PTIONAL 245364-U Rosemount Analytical April 2000 2-13 Model 755A Oxygen Analyzer...
  • Page 34 NPACKING AND NSTALLATION OTES 2-14 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 35: Initial Tartup And

    Preparatory to startup and calibration, the operator should study Figures 3-1, 3-2, and Table 3-1. Together they give locations and summarized descriptions of operating controls and adjustments of the Model 755A. 3.1 SELECTION OF RECORDER OXYGEN RANGE The digital display provides readout over the full range of 0.00% to 100.00% oxygen, eliminating the requirement for expanded-scale operation.

  • Page 36: Digital Display

    With suitable upscale standard gas flowing through the SPAN Control (R16) analyzer, the SPAN Control is adjusted for appropriate reading on display or recorder. 3-1. M 755A F IGURE ODEL RONT ANEL ONTROLS Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 37 R41, Recorder Zero Suppression Coarse Adjustment, and R104, Recorder Zero Suppression Fine Adjustment, are adjusted for the additional 10% required to reach the desired zero suppression level (90% desired level - 80% zero suppression Jumper). 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 38 Use to set fullscale current output at 20mA for 4 to 20mA or 0 to 20mA board or at Adjustment R2 50mA for 10 to 50mA board. Refer to Figure 3-2 for component locations. 3-1. M 755A I ABLE ODEL NTERNAL DJUSTMENTS Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 39 3. Temporarily place Recorder Oxygen Span Jumper in 100% oxygen (i.e., 1X gain) position. The digital display will now read the applied zero suppression voltage in 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 40: Startup Procedure

    If digital display gives over-range indication, the probable cause is hang-up of the suspension within the detector assembly. To correct this condition, turn power OFF; tap detector compartment with fingers; wait 30 seconds; re-apply power. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...

  • Page 41: Calibration

    For example, if this range limit is 21% (or somewhat greater than 21%), the usual upscale standard gas is dry air (20.93% oxygen). Typical examples of standard gases for recorder oxygen ranges are shown in Table 3- 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 42: Calibration With Downscale And Upscale Standard Gases

    Section 3.4.2). If proper reading is not obtained by an adjustment of the ZERO Control, refer to Section 6, Routine Servicing. 2. Set upscale calibration point as follows: a. Verify that front panel TEST switch is set to NORM. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 43: Calibration Of Automatic Pressure Compensation

    Compound Range Pressure Pressure Gauge or Gauge Mercury Manometer Vacuum Pump Sample Sample In 755A 10 psig cc/min 3-3. C IGURE ALIBRATION BY RESSURE ECREASE ETUP 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 44: Compensation For Composition Of Background Gas

    During adjustment of the ZERO and SPAN controls (on the analyzer door), the instrument is set to indicate, not the true oxygen content of the downscale and 3-10 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 45: Computing Adjusted Settings For Zero And Span Controls

    Calibration and measurement must be made at the same pressure in the detector cell unless the user makes the compensation referred to in Section 4.2. in Std Adjusted value = % O in Std + [100(Spl-Std)]-100(Spl-Std) 245364-U Rosemount Analytical April 2000 3-11 Model 755A Oxygen Analyzer...

  • Page 46: Oxygen Equivalents Of Common Gases

    755A O ODEL XYGEN NALYZER Example: EQUIV. % AS O Acetylene, C -0.612 Sample is oxygen in a background of Allene, C -0.744 . (Oxygen equivalent of CO is - Ammonia, NH -0.479 0.623). Argon, A -0.569 Standard is the following: Bromine, Br -1.83...

  • Page 47: Dual Alarm Option

    755A O ODEL XYGEN NALYZER 3.5 DUAL ALARM OPTION 3.5.1 I NITIAL ALIBRATION AND ELECTION OF ETPOINTS FOR LARMS The ALARM 1 and ALARM 2 circuits have independent setpoint and deadband adjustments (Table 3-1, Figure 3-2). Initially the ALARM 1 and ALARM 2 setpoint adjustments must be calibrated by means of the ALARM 1 and ALARM 2 calibration adjustments.

  • Page 48: Selection Of Deadband

    1. RELAYS SHOWN IN ENERGIZED POSITION. NOTES: +15V ALARM 1 -15V RESET ALARM 1 COMMAND ALARM 2 RESET ALARM 2 COMMAND 3-4. S IGURE CHEMATIC IRCUIT OF LARM ELAY SSEMBLY 3-14 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 49: Routine Operation

    Section 3.3.4. 4.3 CALIBRATION FREQUENCY The appropriate calibration interval will depend on the accuracy required in the particular application, and is best determined by keeping a calibration log. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 50 OUTINE PERATION OTES Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 51: Theory

    This is analogous to the magnetization of a piece of soft iron. Diamagnetic gases are analogous to non-magnetic substances. With the Model 755A, the volume magnetic susceptibility of the flowing gas sample is sensed in the detector/magnet assembly. As shown in the functional diagram of Figure 5-2, a dumbbell-shaped, nitrogen-filled, hollow glass test body is suspended on a platinum/nickel alloy ribbon in a non-uniform magnetic field.

  • Page 52: Spherical Body In Non-Uniform Magnetic Field

    (Magnetic Susceptibility = k Sample Gas (Magnetic Susceptibility = k ) Note: As percentage of oxygen in sample gas increases, displacement force (F ) increases. 5-1. S IGURE PHERICAL ODY IN NIFORM AGNETIC IELD Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 53 Source Lamp ASSEMBLY CONTROL ASSEMBLY Shaded Pole Pieces (4) Zero Span % Oxygen Dual Photocell Readout BT1, BT2 5-2. F 755A P IGURE UNCTIONAL IAGRAM OF ODEL ARAMAGNETIC XYGEN EASUREMENT YSTEM 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 54 The magnet assembly includes a sample pre-heating coil. It is connected into the sample line upstream from the detector and is heated to approximately the same temperature as the detector assembly. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 55: Variables Influencing Paramagnetic Oxygen

    RESSURE FFECTS Although normally calibrated for readout in percent oxygen, the Model 755A actually responds to oxygen partial pressure. The partial pressure of the oxygen component in a gas mixture is proportional to the total pressure of the mixture. Thus readout is affected by pressure variations.

  • Page 56: Interferents

    5.3.1 D ETECTOR AGNET SSEMBLY A cross-sectional view of the optical bench and detector assemblies is shown in Figure 5-3B. Source lamp DS1, powered by a supply circuit on the Case Board Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 57 R16 modifies the value of the input resistance and hence the signal amplification factor. Adjustment range is approximately ±30%. The SPAN adjustment permits establishing an upscale calibration point on the display 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 58 Analog Output Circuit . The output from U10 is provided as an input to the recorder output amplifier. This circuitry provides zero suppression, scale expansion, and amplification preparatory to use for potentiometric recorder, voltage-to-current conversion for current recorder, and/or alarm functions. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 59: Case Board

    140°F (60°C). Temperature is sensed by a thermistor on the Control Board adjacent to critical electronic components. The circuit provides on-off control of heater element HR3 via TRIAC Q7. Heater HR3 is located in the heater/fan assembly. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 60: Isolated Current Output Board (Optional)

    The alarm relay assembly has two single-pole, double-throw relays, one each for the ALARM 1 and ALARM 2 contacts. Alarm output connections are on the terminal board shown in Figure 2-1. 5-10 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 61: Section 6. Electronic Circuit Analysis

    LECTRONIC IRCUIT NALYSIS 6.1 OVERVIEW The electronic circuitry of the Model 755A Oxygen Analyzer consists of the following: • A detector compartment heater circuit. • A detector heater circuit. • A ±15VDC power supply. • A voltage regulating circuit for a stable light source.
  • Page 62 0 ° 0 ° 180 ° COMP 1 COMP 2 +15V +15V OUTPUT 21.5K -15V +15V -15V 3.3K INPUT 4.75K 0.18uF -1.88 VDC Source 6-1. T OR C IGURE OMPARATOR IRCUIT Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 63: Ramp Generator

    -2.3V 6 Hz 249K +15V +15V INPUT FROM 590K MULTIVIBRATOR -15V 1.0uF 210K -15V to 1.88V ±0.3V 63.4K 9.09K 37.4K 2200uF COMPARATOR -15V 56.2 .18uF 169K -15V 6-2. R IGURE ENERATOR 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 64: Case Heater Control Circuit

    590K TO POWER SUPPLY CR11 19 VAC 21.5K 1.0uF 210K 3.3K 37.4K 2200uF CR10 4.75K .18uF 56.2 -15V 11.0K .18uF 9.07K 63.4K .01uF 169K -15V 6-3. C IGURE EATER ONTROL IRCUIT Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 65: Case Heater Circuit

    RT1, R84 of the bridge circuit. If the temperature at RT1 is low, the potential at the non-inverting terminal of comparator 4 is more negative and the output is -15V. HEATER MOTOR NEUTRAL 120V 6-4. C IGURE EATER IRCUIT 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 66: Detector Heater Control Circuit

    The bridge is designed to maintain the temperature of the detector at 150°F (65.5°C). The junction point between R55 and R56 is maintained at a specific voltage since these resistances maintain a definite ratio. The thermistor resistance is 149 K at 150°F (65.5°C) Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...

  • Page 67: Detector Light Source Control Circuit

    This AC voltage is rectified by CR7 and CR8 and filtered (C32), presenting an approximate +8.5V bus to the current-limiting Darlington configuration of Q4. Q4 controls the basic amount of current through DS1. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 68: Detector With First Stage Amplifier And Pressure Compensation

    The test body is constructed of two hollow glass spheres forming a dumbbell shape. They are filled and sealed with pure, dry nitrogen. Around the test body, a titanium wire is chemically etched in order to form a feedback loop that can create a Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...
  • Page 69 U2 to counteract any electrical offset resulting from imbalance in the detector and/or photocells BT1 and BT2. The output current that U2 must provide to restore the dumbbell is a measure of the 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 70 While the absolute accuracy is of importance, more important yet is the ability of these circuits to remain stable despite temperature variations that may occur during normal instrument usage. 6-10 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 71: Compensation Circuits

    +10.00V REFERENCE REFERENCE Reference Voltages TRIM -10.00V CAL 1 To Test Switch CAL2 PRESS To Analog SENSOR Divider U6 +10V -10V 6-8. P IGURE RESSURE IGNAL AND EFERENCE OLTAGE IRCUITS 245364-U Rosemount Analytical April 2000 6-11 Model 755A Oxygen Analyzer...

  • Page 72: Buffer Amplifiers U10 And Associated Anticipation Function

    The output of the ADC consists of binary-coded decimal characters that are input to the liquid crystal controller and display chip characters sequentially in time. The BCD characters are converted into seven-line codes to drive the bar segments of the liquid crystal display. 6-12 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 73: Analog Output Circuits For Recorder And Alarms

    Required span is 100% oxygen; thus a gain of 1 is selected with the jumper. Required zero suppression is 0%; thus, the Zero Suppression Selection Jumper is removed, and the Zero Suppression Potentiometer is set for 0%. 245364-U Rosemount Analytical April 2000 6-13 Model 755A Oxygen Analyzer...
  • Page 74 10 mV, 0 to 100 mV, 0 to 1V, or 0 to 5VDC for a potentiometric recorder. Current Output Receptacle J1. This connector accepts the optional plug-in current-output board. Dual Alarm Amplifier Circuit. This circuit drives the optional 638254 Alarm Relay Assembly. 6-14 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 75 10mV Suppression (0% to 25% Oxygen) -REF 8.33K Recorder Zero Suppression (Jumper Selectable) Resistor Values are in Ohms. 6-10. S IGURE IMPLIFIED NALOG UTPUT IRCUIT FOR ECORDER HOWING HREE ANGES 245364-U Rosemount Analytical April 2000 6-15 Model 755A Oxygen Analyzer...
  • Page 76 LECTRONIC IRCUIT NALYSIS OTES 6-16 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 77: Routine Ervice And

    If instrument readings do not meet specifications, the first step in troubleshooting is to isolate the analyzer from the sample stream and the sample-handling system. Admit downscale and upscale standard gases to the analyzer. Observe readout on digital display and on recorder (if used). 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 78: Detector Component Checks

    450 mA). 3. Measure between the orange and red wires. The reading should be approximately the same as step 2. If photocell readings not correct, replace photocell per Section 7.3.3. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 79: Suspension

    4. Remove the two screws at the bottom of the detector assembly, slide detector out. 5. Install replacement detector assembly and connect cable to J12. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 80: Detector/Magnet Assembly

    11. Connect the voltmeter between TP10 and circuit ground. Adjust front panel ZERO control (R13) for reading of exactly zero on voltmeter. With all internal adjustments now properly set, the instrument may be calibrated in the normal manner. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 81: Detector/Magnet Assembly

    3. If retaining set screw for lamp is accessible, proceed to step 6. If the set screw is not accessible continue to step 4. 4. Remove the two screws holding the optical bench assembly/detector assembly to 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 82 14. Refer to Figure 7-5. The red line on the lamp must be aligned with the retaining set screw. Insert lamp into mounting hole until it extends 1/4 inch. Tighten set screw. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical...

  • Page 83: Photocell Replacement And Adjustment

    Place a digital voltmeter on the wiper of the front panel ZERO control (R13) and ground (TP7) ground on the Control Board. Adjust front panel ZERO control for 0.0 VDC. b. Place the voltmeter from the bottom of R10 and TP7 (see Figure 7-5), adjust 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...

  • Page 84: Heating Circuits

    RT1. Also, connect an AC voltmeter from the hot side of the line to the neutral side of F2. Set the decade box for 20.2K ohms to simulate RT1 resistance at controlling temperature. The voltmeter should now show pulses of 1 VAC. Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 85 10 and 11 of detector connector J12. The sensor resistance, as measured at these pins, should be 1M ohm at 25°C and approximately 149K ohms at operating temperature of 65°C. 245364-U Rosemount Analytical April 2000 Model 755A Oxygen Analyzer...
  • Page 86 OUTINE ERVICE AND AINTENANCE OTES 7-10 Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...

  • Page 87: Replacement

    ARTS The following parts are recommended for routine maintenance and troubleshooting of the Model 755A Oxygen Analyzer. If the troubleshooting procedures in Section 5 do not resolve the problem, contact your local Rosemount Analytical service office. A list of Rosemount Analytical Service Centers is located in the back of this manual.
  • Page 88 EPLACEMENT ARTS 652225 Transducer Assembly 621023 Current Output Board (0 to 20mA, 4 to 20mA) 631773 Case Board 652220 Control Board Model 755A Oxygen Analyzer April 2000 Rosemount Analytical 245364-U...
  • Page 89 8. Do not place cylinders where they may become part of an electric circuit. When electric arc welding, precautions must be taken to prevent striking an arc against the cylinder. Rosemount Analytical Inc. 4125 E • A 92807-1802 • 714-986-7600 • FAX 714-577-8006...
  • Page 90 (blank)
  • Page 91 SUCCESSOR INTEREST TO THE GOODS PROVIDED HEREUNDER. Force Majeure. Seller shall not be liable for failure to perform due to labor strikes or acts beyond Seller's direct control. Rosemount Analytical Rosemount Analytical Inc. 4125 E • A 92807-1802 • 714-986-7600 • FAX 714-577-8006...
  • Page 92 (blank)
  • Page 93 National Response Center 1-800-654-7768 NTERNATIONAL Contact your local Rosemount Sales and Service office for service support. ACTORY For order administration, replacement Parts, application assistance, on-site or factory repair, service or maintenance contract information, contact: Rosemount Analytical Inc.
  • Page 94 (blank)

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