Instruction Manual 245364-V May 2002 Model 755A Oxygen Analyzer http://www.processanalytic.
ESSENTIAL INSTRUCTIONS READ THIS PAGE BEFORE PROCEEDING! Rosemount Analytical designs, manufactures and tests its products to meet many national and international standards. Because these instruments are sophisticated technical products, you MUST properly install, use, and maintain them to ensure they continue to operate within their normal specifications.
Instruction Manual 245364-V May 2002 Model 755A TABLE OF CONTENTS PREFACE...........................................................................................................................................P-1 Definitions ...........................................................................................................................................P-1 Intended Use Statement.....................................................................................................................
Instruction Manual 245364-V May 2002 3-0 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 4-0 4-1 4-2 4-3 5-0 5-1 5-2 5-3 5-4 5-5 5-6 5-7 5-8 5-9 ii Contents Model 755A OPERATION .........................................................................................................................3-1 Overview................................................................................................................................3-1 Selection of Recorder Oxygen Range......................................
Instruction Manual 245364-V May 2002 Model 755A 6-0 6-1 6-2 6-3 6-4 6-5 SERVICE AND MAINTENANCE ..........................................................................................6-1 Initial Checkout with Standard Gases ...................................................................................6-1 Detector Component Checks ................................................................................................6-2 a. Detector..........................................................
Instruction Manual 245364-V May 2002 Model 755A LIST OF ILLUSTRATIONS Figure 1-1. Figure 1-2. Figure 2-1. Figure 2-2. Figure 2-3. Figure 2-4. Figure 2-5. Figure 2-6. Figure 2-7. Figure 2-8. Figure 3-1. Figure 3-2. Figure 3-3. Figure 3-4. Figure 4-1. Figure 4-2. Model 755A Oxygen Analyzer ............................................................................... 1-1 Model 755A Component and Adjustment Locations ............................................. 1-3 Electrical Connections .................
Instruction Manual 245364-V May 2002 Model 755A LIST OF DRAWINGS (Located in rear of manual) 617186 617731 620434 632349 652219 652222 Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 vi Contents Model 755A Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 Model 755A PREFACE The purpose of this manual is to provide information concerning the components, functions, installation and maintenance of the 755A. Some sections may describe equipment not used in your configuration. The user should become thoroughly familiar with the operation of this module before operating it. Read this instruction manual completely.
Instruction Manual 245364-V May 2002 Model 755A 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 If this equipment is used in a manner not specified in these instructions, protective systems may be impaired.
Instruction Manual 245364-V May 2002 Model 755A 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, 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).
Instruction Manual 245364-V May 2002 Model 755A GENERAL PRECAUTIONS FOR HANDLING AND STORING HIGH PRESSURE GAS CYLINDERS Edited from selected paragraphs of the Compressed Gas Association's "Handbook of Compressed Gases" published in 1981 Compressed Gas Association 1235 Jefferson Davis Highway Arlington, Virginia 22202 Used by Permission 1. Never drop cylinders or permit them to strike each other violently. 2.
Instruction Manual 245364-V May 2002 Model 755A DOCUMENTATION The following May 2002 instruction materials are available. representative to order. Contact Customer Service or the local 245364 Instruction Manual (this document) COMPLIANCES The Model 755A Oxygen Analyzer (General Purpose Enclosure) has been designed to meet the applicable requirements of the U.S.
Instruction Manual 245364-V May 2002 P-6 Preface Model 755A Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 Model 755A SECTION 1 DESCRIPTION AND SPECIFICATIONS The basic electronic circuitry is incorporated into two master boards: The Control Board Assembly and the Case Circuit Board Assembly (see Figure 1-2, page 1-3). The Control Board has a receptacle which accepts optional circuit boards, thus permitting inclusion of such features as current output. 1-1 OVERVIEW The Model 755A Oxygen Analyzer provides digital readout of the oxygen content of a flowing gas sample.
Instruction Manual 245364-V May 2002 Model 755A 1-4 RECORDER VOLTAGE AND CURRENT OUTPUTS 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.
Instruction Manual 245364-V May 2002 Model 755A Location for Optional Current Output Board Control Board Span Jumper Select ZERO Control SPAN Control Recorder Output Jumper Select Zero Suppression Adjustment CAL2 Adjustment, Pressure Compensation CAL1 Adjustment, Pressure Compensation Alarm Relay Assembly (Alarm Option) Zero Offset Jumper Select Case Board Recorder Output TB2 Case Heater Assembly NO. 1 NO COM HOT NC RESE NO.
Instruction Manual 245364-V May 2002 Model 755A 1-7 SPECIFICATIONS a. General1 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.
Instruction Manual 245364-V May 2002 Model 755A c. 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 ........................
Instruction Manual 245364-V May 2002 1-6 Description and Specifications Model 755A Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 Model 755A SECTION 2 INSTALLATION 2-1 UNPACKING CAUTION Carefully examine the shipping carton and contents for signs of damage. Immediately notify the shipping carrier if the carton or its contents are damaged. Retain the carton and packing materials until the instrument is operational. 2-2 LOCATION AND MOUNTING The analyzer is designed to meet NEMA 3R enclosure requirements and may be mounted outdoors.
Instruction Manual 245364-V May 2002 b. Model 755A c. Recorder Connections Potentiometric Output Insert Recorder Output Selection Jumper, Figure 2-2 (page 2-3), in position appropriate to the desired output; 10 mV, 100 mV, 1V or 5V. NOTE Route recorder cable through a separate conduit, not with power cable or alarm output cable. On TB2, Figure 2-1 (page 2-2), connect leads of shielded recorder cable to "MV+" AND "COM" terminals.
Instruction Manual 245364-V May 2002 Model 755A R3 R4 R8 R9 CR2 R5 R6 R2 R1 U6 I G O 1 2 3 4 U3 U2 C5 I G O C4 C2 U4 U1 U5 Control Board I G O C3 CR1 C1 J1 Current Output Board Recorder Output Voltage Selection Jumper 5V 1V 0.1V 0.01V JP3 Figure 2-2.
Instruction Manual 245364-V May 2002 d. Model 755A Isolated Current Output (Optional) 1. Verify that the Current Output Board appropriate to desired output is properly in place. See Figure 2-2, page 2-3. If originally ordered with analyzer, the board is factory installed. 2. On TB2, Figure 2-1 (page 2-2), connect leads of shielded recorder cable to "MA+" and "-" terminals. 3.
Instruction Manual 245364-V May 2002 Model 755A g. Alarm Relay Characteristics The ALARM 1 and ALARM 2. Outputs of the Alarm Relay Assembly are provided by two identical single-pole double-throw relays.
Instruction Manual 245364-V May 2002 Model 755A A. Typical ALARM 1 Setting When input signal moves upscale through this point, the coil of ALARM 1 relay (K1) is energized, providing continuity between the common and normally-closed contacts of the relay.
Instruction Manual 245364-V May 2002 Model 755A 2-5 CALIBRATION GASES a. Zero Calibration Gas Zero-based range - Normally uses a oxygen-free gas, typically nitrogen. Zero-suppressed range - Uses a blend consisting of a suitable percentage of oxygen contained in a background gas, typically nitrogen. b. available for applications involving corrosive gases. With corrosive gases, complete drying of the sample is desirable, as most of these gases are practically inert when totally dry.
Instruction Manual 245364-V May 2002 Model 755A pressure during operation. The arrangement required to obtain appropriate pressure control will depend on the application. Refer to special instructions included in Section 2-6c (page 2-9), Normal Operation at Positive Gauge Pressures; or Section 2-6d (page 2-9), Operation at Negative Gauge Pressures. Needle Valves Model 755A Oxygen Analyzer Sample In Two Micron Filter Downscale Standard Gas To Vent Flowmeter Upscale Standard Gas Figure 2-7.
Instruction Manual 245364-V May 2002 Model 755A c. Pressure at Sample Inlet (All Instruments) - Normally, the sample is supplied to the analyzer inlet at a positive gauge pressure in the range of 0 to 10 psig (0 to 69 kPa). CAUTION HIGH PRESSURE SURGES High pressure surges during admission of sample or standard gases can damage the detector.
Instruction Manual 245364-V May 2002 f. Model 755A Corrosive 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. WARNING Leaks must be corrected before introduction of flammable sample and/or application of electrical power.
Instruction Manual 245364-V May 2002 Model 755A 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 21. WARNING POSSIBLE EXPLOSION HAZARD This analyzer is of the type capable of analysis of sample gases which may be flammable.
Instruction Manual 245364-V May 2002 Model 755A A. Option with Flow Indicator B. Option with Pressure Indicator or Alarm Affix Warning Label Affix Warning Label Analyzer Door Analyzer Door 190697 Purge Inlet Fitting Flow Indicator 645835 Purge Outlet Fitting Purge Supply 190697 Purge Inlet Fitting Purge Supply Pressure Indicator or Alarm 645835 Purge Outlet Fitting Components in dashed line are supplied by customer. Figure 2-8.
Instruction Manual 245364-V May 2002 Model 755A SECTION 3 OPERATION 3-1 OVERVIEW Preparatory to startup and calibration, the operator should study Figure 3-1 (page 3-2), Figure 3-2 (page 3-7) and Table 3-1 (page 35). Together they give locations and summarized descriptions of operating controls and adjustments of the Model 755A. 3. Select the required zero suppression by appropriate settings of the following: a. Set Recorder Zero Suppression Jumper for fixed value of 0%, 20%, 40%, 60% or 80% oxygen. b.
Instruction Manual 245364-V May 2002 Model 755A 6 Digit LCD Display ZERO SPAN PRESS CAL1 NORM PRESS CAL 2 REC OFFSET ZERO Adjust TEST Switch SPAN Adjust Rosemount Analytical Model 755A Oxygen Analyzer FUNCTION CONTROL Digital Display (LCD) Readout of sample oxygen content (0.00% to 100.00%) or selected test function, depending on position of TEST switch. TEST Switch (S1) Selects variable desired for readout on digital display.
Instruction Manual 245364-V May 2002 Model 755A NOTE: The Zero and Span adjustments on the analyzer door are used only for the calibration of the digital readout for 0 to 100% oxygen. The suppressed recorder ranges may only be set up after the digital readout has been calibrated. When setting up a suppressed recorder range, use only R41, R104 (setpoint) and R88 (Span) for adjustments. DO NOT RE-ADJUST THE ZERO AND SPAN CONTROLS ON THE ANALYZER DOOR.
Instruction Manual 245364-V May 2002 Model 755A • Desired oxygen range for recorder output: 99% to 100%. detector compartment with fingers; wait 30 seconds; re-apply power. • Front panel TEST switch is set to position 4, and Recorder Oxygen Span Jumper is placed in 100% oxygen (1X gain) position. • Required zero suppression is 99% oxygen, thus Recorder Zero Suppression Jumper is set in 80% position, and Recorder Zero Suppression Adj4ustments R41 and R104 are set for a reading of 99.
Instruction Manual 245364-V May 2002 Model 755A 2. A zero-suppressed range uses a blend consisting of a suitable percentage of oxygen contained in a background gas, typically nitrogen. The upscale standard gas is required to establish a calibration point at or near the upper range limit. For example, if this 0 to 1 0 to 10 0 to 100 range limit is 21% (or somewhat greater than 21%), the usual upscale standard gas is dry air (20.93% oxygen).
Instruction Manual 245364-V May 2002 ITEM Model 755A CONTROL DESCRIPTION 1 Provides selectable span of 100%, 20%, 10%, 5%, 2%, or 1% oxygen for analog output Recorder Oxygen Span to recorder and alarms. Note that on the circuit board the jumper positions are marked Selection Jumper according to the amplifier gain. 2 Recorder Zero Suppression Selection Jumper Used in combination with item 3 to establish required zero suppression to obtain desired range for analog output to recorder and alarms.
Instruction Manual 245364-V May 2002 Model 755A Control Board 19 Door R3 R4 R8 R9 CR2 R5 R6 R2 R1 18 U6 I G O 1 2 3 4 U3 U2 C5 I G O C4 C2 U4 15 U1 U5 I G O C3 CR1 C1 J1 1 16 17 14 2 13 6 7 5 12 3 4 9 8 10 11 Refer to Table 3-2, page 3-6, for descriptions. Figure 3-2. Model 755A Internal Adjustments Locations Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 c. Model 755A Calibration with Downscale and Upscale Standard Gases a. Verify that front panel TEST switch is set to NORM. 1. Set downscale calibration point as follows: b. Pass upscale standard gas through analyzer at same flow rate as was used for downscale standard gas. Allow gas to purge analyzer for minimum of 3 minutes. a. Set TEST switch (on analyzer door) to NORM. b. Pass downscale standard gas through analyzer at suitable flow rate, preferably 250 cc/min.
Instruction Manual 245364-V May 2002 Model 755A F1 Pressure Gauge Compound Range Pressure Gauge or Mercury Manometer Vacuum Pump PR1 Sample In 10 psig V1 250 cc/min Sample 755A In V3 V2 V4 Figure 3-3. Calibration by Pressure Decrease Setup Standard Procedure: Calibration by Pressure Decrease 1. Verify that the Pressure Compensation Option is selected, i.e., Jumper inserted between E1 and E3 on the Control Board. 2.
Instruction Manual 245364-V May 2002 Model 755A 3-5 COMPENSATION FOR COMPOSITION OF BACKGROUND GAS Any gas having a compensation other than 100% oxygen contains background gas. The background gas comprises all nonoxygen constituents. To select a random example from Table 3-3 (page 3-11), if analyzer response to oxygen is +100%, the response to xenon would be -1.34%. Although instrument response to most gases other than oxygen is comparatively slight, it is not in all cases negligible.
Instruction Manual 245364-V May 2002 Model 755A Example: Sample is oxygen in a background of CO2. (Oxygen equivalent of CO2 is 0.623). Standard is the following: Pure nitrogen for ZERO gas. 21% oxygen, 79% nitrogen for SPAN gas. (Oxygen equivalent of nitrogen is -0.358). With nitrogen ZERO gas flowing, Adjusted Value is the following: 0 0+ [100((-0.623)-(-0.358))]-100((-0.623)-(-0.358)) 100 = 100 0-100(-0.265) 100 = 0.265 Display should be made to read 0.265% oxygen with ZERO control.
Instruction Manual 245364-V May 2002 Model 755A Calibration of ALARM 2, LOW: 3-6 DUAL ALARM OPTION a. 1. Rotate setpoint potentiometer R67 full counterclockwise. Initial Calibration and Selection of Setpoints for Alarms The ALARM 1 and ALARM 2 circuits have independent setpoint and deadband adjustments (see Table 3-1, page 3-5, and Figure 3-2, page 3-7). Initially the ALARM 1 and ALARM 2 setpoint adjustments must be calibrated by means of the ALARM 1 and ALARM 2 calibration adjustments. 1.
Instruction Manual 245364-V May 2002 Model 755A b. Selection of Deadband The desired deadband may be selected with the appropriate trimming potentiometer: ALARM 1 = R73 ALARM 2 = R78 For any setpoint, deadband is adjustable from 1% of fullscale (counterclockwise limit) to 20% of fullscale (clockwise limit). Deadband is essentially symmetrical with respect to setpoint. NO 1 2. CR1 AND CR2 ARE ANY 600V, 1A DIODE. 1. RELAYS SHOWN IN ENERGIZED POSITION.
Instruction Manual 245364-V May 2002 Model 755A 3-8 EFFECT OF BAROMETRIC PRESSURE CHANGES ON INSTRUMENT READOUT 3-7 ROUTINE OPERATION After the calibration procedure of Section 3-4 (page 3-4), admit sample gas to the analyzer at the same pressure and the same flow rates used for the zero and span gases. The instrument will now continuously indicate the oxygen content of the sample gas.
Instruction Manual 245364-V May 2002 Model 755A SECTION 4 THEORY 4-1 PRINCIPLES OF OPERATION Oxygen is strongly paramagnetic while most other common gases are weakly diamagnetic. The paramagnetism of oxygen may be regarded as the capability of an oxygen molecule to become a temporary magnet when placed in a magnetic field. This is analogous to the magnetization of a piece of soft iron. Diamagnetic gases are analogous to non-magnetic substances.
Instruction Manual 245364-V May 2002 Model 755A Where: b. c = A function of the magnetic field strength and gradient k = Magnetic susceptibility of the surrounding gas ko = Magnetic susceptibility of the sphere The forces exerted on the two spheres of the test body are thus a measure of the magnetic susceptibility of the sample and, therefore, of its oxygen content.
Instruction Manual 245364-V May 2002 Model 755A Displacement Torque Electromagnetic Axis Restoring Torque Restoring Current Balancing Weight Electromagnetic Axis Nitrogen-Filled Hollow Glass Test Body Titanium Wire Conductor Mirror Balancing Weight Restoring Current Platinum/Nickel Alloy Suspension Ribbon TEST BODY DETAIL Displacement Torque Restoring Torque Restoring Current Magnet Test Body Source Lamp DS1 DETECTOR/MAGNET ASSEMBLY CONTROL ASSEMBLY Shaded Pole Pieces (4) Dual Photocell BT
Instruction Manual 245364-V May 2002 Model 755A Sample Pre-Heating Coil Sample Inlet Tube Sample Outlet Tube Magnet Assembly Detector Assembly Optical Bench Assembly Mounting Screws (2) A.
Instruction Manual 245364-V May 2002 Model 755A passing through a coil maintained at approximately the same temperature as the detector. 4-2 VARIABLES INFLUENCING PARAMAGNETIC OXYGEN MEASUREMENTS Variables that influence paramagnetic oxygen measurements include: operating pressure, Section 4-2a below; sample temperature, Section 4-2b below; interfering sample components, Section 4-2c (page 4-5); and vibration 4-2d (page 4-5). a. c.
Instruction Manual 245364-V May 2002 Model 755A 4-3 ELECTRONIC CIRCUITRY Electronic circuitry and internal interconnection wiring is shown in the schematic diagrams and wiring diagram in the rear of this manual. For detailed circuit analysis, refer to Section 5. a. Detector/Magnet Assembly A cross-sectional view of the optical bench and detector assemblies is shown in Figure 5-3B.
Instruction Manual 245364-V May 2002 Model 755A where provides zero suppression, scale expansion, and amplification preparatory to use for potentiometric recorder, voltage-to-current conversion for current recorder, and/or alarm functions.
Instruction Manual 245364-V May 2002 Model 755A The circuit provides on-off control of heater element HR3 via TRIAC Q7. Heater HR3 is located in the heater/fan assembly. voltage regulator, providing regulated outputs of +15V and -15V. Detector Temperature Control This circuit maintains the detector at a controlled temperature of 150°F (66°C). Temperature is sensed by RT1, a resistance element permanently attached to the detector assembly.
Instruction Manual 245364-V May 2002 Model 755A SECTION 5 CIRCUIT ANALYSIS 5-3 CASE HEATER CONTROL CIRCUIT 5-1 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.
Instruction Manual 245364-V May 2002 Model 755A 100µ -1.7V -15V 159mV 180° ON OFF ON OFF ON OFF COMP 1 COMP 2 360° 0° 180° 0° +15V +15V R69 2M -1 + R71 21.5K OUTPUT -15V R70 20M +15V -2 + R68 3.3K -15V R73 INPUT R72 4.75K C38 0.18uF 20M -1.88 VDC Source Figure 5-1. Two-Comparator OR Circuit An approximate 8V peak-to-peak AC signal is applied to comparators 1 and 2. As the signal starts going positive, comparator 2 transistor ceases conducting and comparator 1 transistor is off.
Instruction Manual 245364-V May 2002 Model 755A Capacitor C36 is added to the input circuit to delay the incoming AC signal so that the pulses will occur at or just after the line frequency crossover point. OFF OFF Circuits for a ramp generator (Figure 5-2 below) and a temperature-sensing bridge are part of the case heater control circuit (Figure 5-3, page 5-4 and Figure 5-4, page 5-5). +2.3V OFF -15V -2.
Instruction Manual 245364-V May 2002 Model 755A +15V T1 120 V RMS R69 2M 19 VAC TO POWER SUPPLY R67 10K R72 4.75K R68 - 590K 10K + C37 1.0uF 20M R79 10K R75 CR11 Q6 T2 210K 2 + R76 37.4K 3.3K C36 R77 3 R70 R71 21.5K CR9 249K R74 1 + 19 VAC 12 R78 - R73 CR10 C40 2200uF 20M .18uF -15V R82 9.07K C39 .01uF RT1 R83 11.0K 63.4K R84 169K R81 56.2 R86 R85 R80 10K 20M C38 .18uF - R87 10K 4 + -15V Figure 5-3.
Instruction Manual 245364-V May 2002 Model 755A page 5-3 and Figure 5-4 below) is to delay the timing pulse, relative to line frequency, so that a pulse arrives at the gate of Triac Q7 as the line potential just passes the zero-volt crossover point (0° and 180° of line phase). At the beginning of the next 100 microsecond pulse, comparator 4 output is again -15V, with zero volts on the base of Q6. Q6 again conducts, discharging C38. At the end of the 100 microsecond pulse, Q6 ceases to conduct.
Instruction Manual 245364-V May 2002 Model 755A If the temperature goes down, RT1 increases in resistance and causes the junction of RT1 and R59 to go positive in voltage value. Since R55 and R56 are of equal resistance, their junction is at zero volts. Therefore, terminal 3 of AR6 is more positive than terminal 2 and the base of Q2 is positive. Q2 conducts, allowing alternating current to flow through heaters 1 and 2.
Instruction Manual 245364-V May 2002 Model 755A and goes through Q5, which acts as a variable feedback resistance, goes to the positive output potential of AR7. 5-5 DETECTOR LIGHT SOURCE CONTROL CIRCUIT Refer to Figure 5-6 below. The detector light source control circuit maintains the light output from the bulb (DS1) as uniform as possible, regardless of voltage fluctuations or aging of the bulb. As DS1 ages, its light emission decreases and its resistance increases.
Instruction Manual 245364-V May 2002 Model 755A 5-6 DETECTOR WITH FIRST STAGE AMPLIFIER AND PRESSURE COMPENSATION CIRCUITS Refer to Figure 5-7 on page 5-10. The detector assembly consists of a test body suspended on a platinum wire and located in a non-uniform magnetic field. The test body is constructed of two hollow glass spheres forming a dumbbell shape. They are filled and sealed with pure, dry nitrogen.
Instruction Manual 245364-V May 2002 Model 755A a. Pressure Compensation Circuit b. Refer to Figure 5-8 on page 5-10. The pressure signal circuit consists of the pressure sensor (transducer) and two associated amplifiers. The sensor provides a voltage output that is proportional to pressure.
Instruction Manual 245364-V May 2002 Model 755A + Vx U4 FRONT PANEL SPAN R16 U6 Vz - U8 + From Pressure Signal Circuit Figure 6-8 To Digital and Analog Circuits +15V R44 200K R19 10 +15V R18 24.9K +15V C2 .01uF -15V 30K C6 - R9 110 + BT1 BT2 1000pf C1 R6 2M CR2 R13 FRONT 20K PANEL ZERO -15V R5 - U1 R9 DETECTOR 20K COARSE ZERO -15V .0022uF + U2 C3 R8 .47uF 1.69K R7 118K DS1 R17 FEEDBACK LOOP Figure 5-7.
Instruction Manual 245364-V May 2002 Model 755A Since the anticipation network attenuates the signal, a gain of 10 is provided by the feedback network associated with U10 to restore the signal to the desired fullscale range of 0 to 10VDC. 5-7 BUFFER AMPLIFIERS U10 AND ASSOCIATED ANTICIPATION FUNCTION Refer to Figure 5-9 below. U10 is a noninverting buffer amplifier that incorporates an anticipation arrangement in its input network, thus providing slightly faster response on the readout device(s).
Instruction Manual 245364-V May 2002 Model 755A 5-8 DIGITAL OUTPUT CIRCUIT Refer to Figure 5-10 on page 5-14. With front panel TEST Switch in position 1, the output signal from buffer amplifier U10 is routed through an attenuator and filter network to an integrating analog-to-digital converter. It converts the signal into an equivalent digital value in the range of 0.00% to 99.99%. Any value above 99.99% will be preceded by an over-range bit, for example, 1.1123.
Instruction Manual 245364-V May 2002 Model 755A Second Stage Amplifier This amplifier is an inverting configuration that provides a signal attenuation of 2X, thus reducing the 10-volt fullscale input signal to obtain a 5-volt fullscale output. This output is routed to: Recorder Output Resistor Network. It provides a jumper-selectable output of 0 to 10 mV, 0 to Rosemount Analytical Inc. A Division of Emerson Process Management 100 mV, 0 to 1V, or 0 to 5VDC for a potentiometric recorder.
Instruction Manual 245364-V May 2002 Model 755A 1X 20K 5X 100K 10X 200K Amplifier Gain (Jumper Selectable) 20X 50X 1M 20K 100X 2M .1uF .1uF Front Panel TEST 20K 1 U13 + 2 3 To Alarm and V/I R50A - 20K + 5V U16 To Recorder 4 1V +REF 100mV 17.8K Continuously Variable Recorder Zero Suppression (0% to 25% Oxygen) -REF Recorder Zero Suppression (Jumper Selectable) Recorder Output (Jumper Selectable) 75K 10mV 20K 25K 80% 10 8.33K 60% 25K 40% Resistor Values are in Ohms.
Instruction Manual 245364-V May 2002 Model 755A SECTION 6 SERVICE AND MAINTENANCE WARNING 6-1 INITIAL CHECKOUT WITH STANDARD GASES POSSIBLE EXPLOSION HAZARD If gases are introduced into this analyzer, the sample containment system must be carefully leak-checked prior to initial startup, 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 2.3.8.
Instruction Manual 245364-V May 2002 Model 755A If photocell readings not correct, replace photocell per Section 1-1a on page 6-7. 6-2 DETECTOR COMPONENT CHECKS a. Detector d. Before concluding that the detector is defective and must be replaced, verify that all components and circuits that could cause erratic readings are operating properly. To isolate the detector as a source of a problem, the source lamp, photocells and suspension should be checked for proper operation. b.
Instruction Manual 245364-V May 2002 Model 755A 5. Install replacement detector assembly and connect cable to J12. 6-3 DETECTOR COMPONENT REPLACEMENT a. Detector Replacement Prior to removal of the detector, remove power from instrument and stop flow of sample gas. 1. Remove the four screws securing the detector cover plate. 2. Disconnect cable from J12 on the detector assembly. NOTE 6. Seat the detector assembly firmly against the magnet pole pieces and tighten attaching screws. 7.
Instruction Manual 245364-V May 2002 Model 755A A. Detector/Magnet Assembly - Exploded View B. Optical Bench - Exploded View Connector J12 Sample Pre-Heating Coil Photocell Lock Screws (2) Connector Board Sample Inlet Tube Sample Outlet Tube Dual Photocell Lamp Retaining Set Screw Detector Assembly Magnet Assembly Lamp Viewing Hole Optical Bench Assembly Source Lamp Assembly Mounting Screws (2) Figure 6-1. Detector/Magnet Assembly A. Connections to Source Lamp and Photocell 10 BRN YEL B.
Instruction Manual 245364-V May 2002 Model 755A R13 U2 C1 Voltmeter Lead R9 Figure 6-3. Detector Adjustment 6-4 SOURCE LAMP REPLACEMENT 1. Remove the four screws securing the detector assembly cover plate. 2. Refer to Figure 6-1 on page 6-4. Carefully remove the small rubber hose connected from the detector/magnet assembly to the detector. 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.
Instruction Manual 245364-V May 2002 Model 755A If the lamp assembly removed from the instrument has four wires, the 633689 Connector Board requires modification. Continue to step 10. NOTE If the Connector Board cannot be satisfactorily modified, a modified 633689 Connector Board may be ordered from the factory. See Section 7. 10. Refer to Figure 6-1 on page 6-4. Remove the two screws holding the Connector Board to the magnet assembly. Carefully remove Connector Board. 13. Reassemble detector, etc.
Instruction Manual 245364-V May 2002 Model 755A a. Photocell Replacement and Adjustment 1. To remove the photocell from the optical bench, perform steps 1 through 5 in Section 6-4 on page 6-5. 2. Install replacement photocell by reversing removal procedure. 3. The photocell must now be adjusted. With zero gas flowing: a. 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.
Instruction Manual 245364-V May 2002 b. Model 755A Detector/Magnet Heating Circuit Heater HR1 is attached to the magnet. Heater HR2 is attached to the rear of the detector. Combined resistance of these two parallel connected heaters, as measured at pins 15 and 16 of detector connector J12, should be approximately 17 ohms. If not, remove pin/leads 14 and 15 from the connector to measure the resistance of HR2 alone. This resistance should be approximately 89 ohms.
Instruction Manual 245364-V May 2002 Model 755A SECTION 7 REPLACEMENT PARTS The following parts are recommended for routine maintenance and troubleshooting of the Model 755A Oxygen Analyzer. If the troubleshooting procedures in Section 6 do not resolve the problem, contact Rosemount Analytical Customer Service Center (see Section 8-1). CAUTION PARTS INTEGRITY Tampering or unauthorized substitution of components may adversely affect safety of this product. Use only factory documented components for repair.
Instruction Manual 245364-V May 2002 Model 755A To identify the configuration of your analyzer, locate the analyzer name-rating plate. The sales matrix identifier number appears on the analyzer name-rating plate. 7-3 MATRIX Each Model 755A Oxygen Analyzer is configured per the customer sales order. Below is the Model 755A sales matrix which lists the various configurations available. 755A MODEL 755A OXYGEN ANALYZER - DIGITAL METER Code 1 2 9 Ranges 0.
Instruction Manual 245364-V May 2002 Model 755A SECTION 8 RETURN OF MATERIAL 8-1 RETURN OF MATERIAL If factory repair of defective equipment is required, proceed as follows: 1. Secure a return authorization from a Rosemount Analytical Inc. Sales Office or Representative before returning the equipment. Equipment must be returned with complete identification in accordance with Rosemount instructions or it will not be accepted. Rosemount CSC will provide the shipping address for your instrument.
Instruction Manual 245364-V May 2002 8-2 Return of Material Model 755A Rosemount Analytical Inc.
Instruction Manual 245364-V May 2002 Model 755A APPENDIX A VAISALA BAROMETRIC PRESSURE TRANSDUCER A-1 An adjustable, precision regulated voltage divider consisting of R1, R2, & VR1 on the Interface Board provide a bridge offset voltage range of + 0.26 to + 0.79 Vdc. OVERVIEW This is applicable if your instrument has a Vaisala Barometric Pressure Transducer installed in it, or, if you are retrofitting a 755A with a Vaisala transducer kit. The Vaisala transducer output range is 0 to +5 Vdc.
Instruction Manual 245364-V May 2002 A-4 Model 755A ADJUSTMENT Circuit adjustment can be made using the built in display together along with a Digital voltmeter. 1. Select position 2 on the front panel selector switch. Connect the DVM (+) to TP1, (-) to TP2 on the INTERFACE Board. Adjust for zero volts as closely as possible using potentiometer VR1 (DMM set to the mVDC range) on this same board.
WARRANTY Goods and part(s) (excluding consumables) manufactured by Seller are warranted to be free from defects in workmanship and material under normal use and service for a period of twelve (12) months from the date of shipment by Seller. Consumables, glass electrodes, membranes, liquid junctions, electrolyte, o-rings, etc., are warranted to be free from defects in workmanship and material under normal use and service for a period of ninety (90) days from date of shipment by Seller.
Instruction Manual 245364-V May 2002 Model 755A Emerson Process Management Rosemount Analytical Inc. Process Analytic Division 1201 N. Main St. Orrville, OH 44667-0901 T (330) 682-9010 F (330) 684-4434 E gas.csc@emersonprocess.com Fisher-Rosemount GmbH & Co. Industriestrasse 1 63594 Hasselroth Germany T 49-6055-884 0 F 49-6055-884209 ASIA - PACIFIC Fisher-Rosemount Singapore Private Ltd.
