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Instruction Manual

245364-V
May 2002

P-4       Preface                                                                                    Rosemount Analytical Inc.    A Division of Emerson Process Management

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.  Cylinders may be stored in the open, but in such cases, should be protected against extremes of

weather and, to prevent rusting, from the dampness of the ground. Cylinders should be stored in the
shade when located in areas where extreme temperatures are prevalent.

3.  The valve protection cap should be left on each cylinder until it has been secured against a wall or

bench, or placed in a cylinder stand, and is ready to be used.

4.  Avoid dragging, rolling, or sliding cylinders, even for a short distance; they should be moved by using a

suitable hand-truck.

5.  Never tamper with safety devices in valves or cylinders.

6.  Do not store full and empty cylinders together. Serious suckback can occur when an empty cylinder is

attached to a pressurized system.

7.  No part of cylinder should be subjected to a temperature higher than 125

°

F (52

°

C). A flame should

never be permitted to come in contact with any part of a compressed gas cylinder.

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.

Summary of Contents for 755A

Page 1: ...Instruction Manual 245364 V May 2002 http www processanalytic com Model 755A Oxygen Analyzer ...

Page 2: ... representative for clarification Follow all warnings cautions and instructions marked on and supplied with the product Inform and educate your personnel in the proper installation operation and maintenance of the product Install your equipment as specified in the Installation Instructions of the appropriate Instruction Manual and per applicable local and national codes Connect all products to the...

Page 3: ...pecifications 1 4 a General 1 4 b Sample 1 4 c Electrical 1 5 d Physical 1 5 2 0 INSTALLATION 2 1 2 1 Unpacking 2 1 2 2 Location And Mounting 2 1 2 3 Voltage Requirements 2 1 2 4 Electrical Connections 2 1 a Line Power Connections 2 1 b Recorder Connections 2 2 c Potentiometric Output 2 2 d Isolated Current Output Optional 2 4 e Output Connections for Dual Alarm Option 2 4 f Alarm Output Connectio...

Page 4: ...on 3 14 3 8 Effect of Barometric Pressure Changes on Instrument Readout 3 14 3 9 Calibration Frequency 3 14 4 0 THEORY 4 1 4 1 Principles of Operation 4 1 a Magnetic Displacement Force 4 1 b Physical Configuration of Detector Magnet Assembly 4 2 4 2 Variables Influencing Paramagnetic Oxygen Measurements 4 5 a Pressure Effects 4 5 b Temperature Effects 4 5 c Interferents 4 5 d Vibration Effects 4 5...

Page 5: ...nt 6 3 6 4 Source Lamp Replacement 6 5 a Photocell Replacement and Adjustment 6 7 6 5 Heating Circuits 6 7 a Case Heater Control Circuit 6 7 b Detector Magnet Heating Circuit 6 8 7 0 REPLACEMENT PARTS 7 1 7 1 Circuit Board Replacement Policy 7 1 7 2 Selected Replacement Parts 7 1 7 3 Matrix 7 2 8 0 RETURN OF MATERIAL 8 1 8 1 Return Of Material 8 1 8 2 Customer Service 8 1 8 3 Training 8 1 APPENDIX...

Page 6: ...l Body in Non Uniform Magnetic Field 4 2 Figure 4 2 Functional Diagram of Model 755A Paramagnetic Oxygen Measurement System 4 3 Figure 4 3 Detector Magnet Assembly 4 4 Figure 5 1 Two Comparator OR Circuit 5 2 Figure 5 2 Ramp Generator 5 3 Figure 5 3 Case Heater Control Circuit 5 4 Figure 5 4 Case Heater Circuit 5 5 Figure 5 5 Detector Heater Control Circuit 5 6 Figure 5 6 Detector Light Source Con...

Page 7: ...Contents v Model 755A LIST OF DRAWINGS Located in rear of manual 617186 Schematic Diagram Master Board Case 617731 Pictorial Wiring Diagram Model 755A 620434 Schematic Diagram Current Output 632349 Installation Drawing Model 755A 652219 Schematic Diagram Control Board 652222 Schematic Diagram Transducer ...

Page 8: ...Instruction Manual 245364 V May 2002 vi Contents Rosemount Analytical Inc A Division of Emerson Process Management Model 755A ...

Page 9: ...wing definitions apply to DANGERS WARNINGS CAUTIONS and NOTES found throughout this publication DANGER Highlights the presence of a hazard which will cause severe personal injury death or substantial property damage if the warning is ignored WARNING Highlights an operation or maintenance procedure practice condition statement etc If not strictly observed could result in injury death or long term h...

Page 10: ...tall operate and service the this equipment should be thoroughly familiar with and strictly follow the instructions in this manual SAVE THESE INSTRUCTIONS DANGER 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 instrumen...

Page 11: ... 1983 Section Three If gases are introduced into this analyzer the sample containment system must be carefully leak checked upon installation and before initial start up during routine maintenance and any time the integrity of the sample containment system is broken to ensure the system is in leak proof condition Leak check instructions are provided in Section 2 7 page 2 10 Internal leakage of sam...

Page 12: ...ocated in areas where extreme temperatures are prevalent 3 The valve protection cap should be left on each cylinder until it has been secured against a wall or bench or placed in a cylinder stand and is ready to be used 4 Avoid dragging rolling or sliding cylinders even for a short distance they should be moved by using a suitable hand truck 5 Never tamper with safety devices in valves or cylinder...

Page 13: ...n Analyzer General Purpose Enclosure has been designed to meet the applicable requirements of the U S Occupational Safety and Health Act OSHA of 1970 if installed in accordance with the requirements of the National Electrical Code NEC of the United States in non hazardous areas and operated and maintained in the recommended manner This product may carry approvals from a certifying agency or may be...

Page 14: ...Instruction Manual 245364 V May 2002 P 6 Preface Rosemount Analytical Inc A Division of Emerson Process Management Model 755A ...

Page 15: ...stal display provides direct digital readout of oxygen concentration In addition a field selectable voltage output is provided as standard An isolated current output of 0 to 20 mA or 4 to 20 mA is obtainable with the optional Current Output Board Current and voltage output may be utilized simultaneously if desired The basic electronic circuitry is incorporated into two master boards The Control Bo...

Page 16: ...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 1 4 RECORDER VOLTAGE AND CURRENT OUTPUTS Voltage Outputs Standard Provided a standard is a jumper selectable voltage output of 0 to 10 mV 0 to 100 mV 0 to 1 V or 0 to 5 V DC Isolated Current Output Option An ...

Page 17: ...ion CAL1 Adjustment Pressure Compensation Location for Optional Current Output Board Control Board ZERO Control SPAN Control Span Jumper Select Recorder Output Jumper Select Zero Offset Jumper Select Recorder Output TB2 Case Board Transformer Power T1 Behind TB1 Alarm Relay Assembly Alarm Option Case Heater Assembly AC Power TB1 Detector Magnet Assembly Detector Magnet As sembly Shock Mount Fuse A...

Page 18: ... pressure variations within 3 of target value and within 2 of fullscale for barometric pressure variations within 5 of target value The target may be set anywhere within range of 2 7 to 3 3 psig 3 psig 18 6 to 22 8 kPa 21 kPa Exhaust vented to atmosphere b Sample Dryness Sample dewpoint below 43 C 110 F sample free of entrained liquids Temperature Limits Maximum 66 C 150 F Minimum 10 C 50 F Operat...

Page 19: ... DC resistive load Setpoint Adjustable from 1 to 20 of fullscale Deadband Adjustable from 1 to 20 of fullscale Factory set at 10 of fullscale d Physical Mounting Standard Panel mount Optional Surface or stanchion mount accessory available Enclosure Classification Meets requirements for NEMA 3R Air Purge Option1 NFPA 496 1989 Type Z purge Weight Approximately 32 5 lbs 14 74 Kg Dimensions Height 13 ...

Page 20: ...Instruction Manual 245364 V May 2002 1 6 Description and Specifications Rosemount Analytical Inc A Division of Emerson Process Management Model 755A ...

Page 21: ...ce of power NOTE Refer to Installation Drawing 642349 at the rear of this manual for recommended cable conduit openings CAUTION ENCLOSURE INTEGRITY With reference to Installation Drawing 642349 any unused cable conduit openings must be securely sealed by permanent closures in order to provide enclosure integrity in compliance with personnel safety and environmental protection requirements The plas...

Page 22: ...ropriate 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 devices are explained in below c 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 On TB2 Figure 2 1 page 2...

Page 23: ... Board Current Output Board 5V 1V 0 1V 0 01V Recorder Output Voltage Selection Jumper Figure 2 2 Control Board Figure 2 3 Connections for Potentiometric Recorder with Non Standard Span 755A Analyzer Potentiometric Recorder Input Terminals Make sure polarity is correct Voltage Divider Customer Supplied Position of Recorder Output Selector Plug Minimum Permissible Resistance for R1 R2 10 mV 1K Ohm 1...

Page 24: ...s e Output Connections for Dual Alarm Option If so ordered the analyzer is factory equipped with alarm output Alternatively the alarm feature is obtainable by subsequent installation of the 618083 Alarm Relay Kit f Alarm Output Connections The alarm output provides two sets of relay contacts for actuation of alarm and or process control functions Leads from the customer supplied external alarm sys...

Page 25: ...onds to the setpoint plus deadband This relay coil is energized when needle moves downscale through the value that corresponds to setpoint minus deadband See Figure 2 5B page 2 6 Alarm Reset Normally both the ALARM 1 and ALARM 2 functions incorporate automatic reset When the meter reading goes beyond the pre selected limits the corresponding relay is de energized When the meter reading returns wit...

Page 26: ...lenoid Valve N H 115 VAC 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 ALARM 1 Setpoint When input signal moves downscale through this point the coil of ALARM 1 relay K1 is de energized providing continuity between the common and normally open contacts of the relay ALARM...

Page 27: ...r or brass components however stainless steel components are 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 For specific corrosive applications consult the factory a Sample Temperature Requirements Sample temperature at the analyzer inlet should be in the range of 50 ...

Page 28: ...rol 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 Figure 2 7 Connection of Typical Gas Selector Panel to Model 755A Oxygen Analyzer Downscale Standard Gas Upscale Standard Gas Sample In Needle Valves Flowmeter Two Micron Filter Model 755A Oxyg...

Page 29: ... analyzer at the same pressure that will be used for the sample during subsequent operation In addition any leakage will result in decreased readout accuracy as compared with operation at atmospheric pressure The minimum permissible operating pressure is 1 9 psig 13 1 kPa Operation below this limit may damage the detector and will void the warranty e Sample Flow Rate Operating limits for sample fl...

Page 30: ...into this analyzer the sample containment system must be carefully leak checked upon installation and before initial start up during routine maintenance and any time the integrity of the sample containment system is broken to ensure the system is in leak proof condition Internal leaks resulting from failure to observe these precautions could result in an explosion causing death personal injury and...

Page 31: ... result in an explosion causing death personal injury and or property damage The kit consists of the following PART NO DESCRIPTION 190697 Purge Inlet Fitting 645835 Purge outlet Fitting 082787 Warning Label 856156 Sealant Duxseal 1 These standards are not applicable to enclosures into which a flammable gas or vapor mixture is introduced such as by a continuous sample containment system that is sub...

Page 32: ...ional 645835 Purge Outlet Fitting 190697 Purge Inlet Fitting Flow Indicator Purge Supply Analyzer Door Affix Warning Label 190697 Purge Inlet Fitting 645835 Purge Outlet Fitting Pressure Indicator or Alarm Purge Supply Analyzer Door Affix Warning Label A Option with Flow Indicator B Option with Pressure Indicator or Alarm Components in dashed line are supplied by customer ...

Page 33: ... 7 1 Verify that Recorder Voltage Output Jumper is in the position appropriate to the recorder 10 mV 100 mV 1 V or 5 VDC 2 Place the Recorder Oxygen Span Jumper in the position appropriate to the desired span Note that on the circuit board switch positions are marked according to the amplifier gain Desired Oxygen Span for Recorder Amplifier Gain Marking on Board 100 1X 20 5X 10 10X 5 20X 2 50X 1 1...

Page 34: ...out on Digital Display Designation 1 Oxygen content of sample 0 00 to 100 00 NORM 2 Pressure Voltage CAL 1 CAL 1 3 Pressure Voltage CAL 2 CAL 2 4 Zero suppression applied to analog output circuit 0 00 to 10 00 VDC ZERO SUPPRESSION ZERO Control R13 Used to establish downscale calibration point on digital display or recorder chart With suitable downscale standard gas flowing through the analyzer the...

Page 35: ...b Readout of Applied Zero Suppression Voltage on Digital Display In order to establish the precise zero suppression required for the desired recorder oxygen range the actual applied zero suppression voltage may be read on the digital display Procedure 1 Verify that Recorder Voltage Output Jumper is in the position appropriate to the recorder 10 mV 100 mV 1 V or 5 VDC 2 Place the front panel TEST s...

Page 36: ...n within the detector assembly To correct this condition turn power OFF tap detector compartment with fingers wait 30 seconds re apply power When on scale reading is obtained allow analyzer to warm up for at least one hour with gas flowing This warm up is necessary because a reliable calibration is obtainable only after the analyzer reaches temperature stability Moreover the resultant elevated tem...

Page 37: ...scale standard gas is dry air 20 93 oxygen Typical examples of standard gases for recorder oxygen ranges are shown in Table 3 2 page 3 6 A TYPICAL ZERO BASED RANGES 0 to 1 Nitrogen 0 9 O2 Balance N2 0 to 10 Nitrogen 9 O2 Balance N2 0 to 100 Nitrogen 100 O2 B TYPICAL ZERO SUPPRESSED RANGES RANGE O2 RECOMMENDED STANDARD GAS RECOMMENDED UPSCALE STANDARD GAS 20 to 21 20 2 0 2 O2 Air 20 93 O2 11 to 21 ...

Page 38: ...tory and does not require readjustment except after replacement of detector 10 Response Time Adjustment R30 Provides adjustment range of 5 to 25 seconds for electronic response time 0 to 90 of fullscale Adjusting clockwise decreases response time 11 Response Ratio Timing Potentiometer R29 Permits compensation for slight gain changes that may result from adjustment of R20 At the factory R29 is adju...

Page 39: ...Management Operation 3 7 Model 755A Refer to Table 3 2 page 3 6 for descriptions Figure 3 2 Model 755A Internal Adjustments Locations R2 R1 R3 R4 R5 R6 R8 R9 CR2 U6 I G O U3 U2 1 2 3 4 I G O C5 C4 C2 U4 U5 I G O C3 CR1 C1 U1 J1 16 17 14 13 7 12 9 11 10 8 4 3 5 6 2 1 15 18 19 Door Control Board ...

Page 40: ...e and Maintenance 2 Set upscale calibration point as follows a Verify that front panel TEST switch is set to NORM 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 c Adjust SPAN Control so that reading on digital display or recorder is appropriate to the upscale standard gas The required readin...

Page 41: ...witch to PRESS CAL 1 and adjust CAL 1 potentiometer R98 see Table 3 2 page 3 6 and Figure 3 2 page 3 7 for a reading of 00 00 5 counts on the display 5 Set TEST switch to NORM and note display reading 6 Start vacuum pump 7 Close V2 and adjust V3 and V4 to decrease the pressure on the sample exhaust by about 3 12 00 inches of water 0 4 psi 23 mm of mercury 3 kPa 8 Adjust CAL 2 potentiometer R99 see...

Page 42: ... to each component of the sample must be shown Table 3 3 page 3 11 lists the percentage oxygen equivalent values for many common gases The percentage oxygen equivalent of a gas is the instrument response to the given gas compared to the response to oxygen assuming that both gases are supplied at the same pressure In equation form To select a random example from Table 3 3 page 3 11 if analyzer resp...

Page 43: ...setting the ZERO control becomes 0 623 0 358 When the ZERO gas is more diamagnetic than the background gas in the sample this difference is negative Use a recorder with below zero capability to set negative values GAS EQUIV AS O2 Acetylene C2H2 0 612 Allene C3H4 0 744 Ammonia NH3 0 479 Argon A 0 569 Bromine Br2 1 83 1 2 Butadiene C4H6 1 047 1 3 Butadiene C4H6 1 944 n Butane C4H10 1 481 iso Butane ...

Page 44: ...rgize ALARM 1 relay K1 Figure 3 4 page 3 13 Energization may be verified by connecting an ohmmeter to relay terminals on 638254 Alarm Relay Assembly Figure 2 1 page 2 2 Calibration of ALARM 2 LOW 1 Rotate setpoint potentiometer R67 full counterclockwise 2 Adjust SPAN control to obtain a display or recorder reading exactly fullscale If the fullscale setting cannot be reached then set to a reading h...

Page 45: ... 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 Figure 3 4 Schematic Circuit of Alarm Relay Assembly 15V 15V ALARM 1 COMMAND ALARM 2 COMMAND J5 1 2 4 6 14 CR1 13 K1 1 5 9 12 8 NO COM NC RESET ALARM 1 CR2 13 K2 1 5 9 12 8 NO COM NC RESET ALARM 2 14 2 CR1 AND CR2 ARE AN...

Page 46: ...ble 3 1 page 3 5 and Figure 3 2 page 3 7 may be desirable to obtain the optimum compromise between response speed and noise 3 8 EFFECT OF BAROMETRIC PRESSURE CHANGES ON INSTRUMENT READOUT If the analyzer exhaust port is vented through a suitable absolute backpressure regulator and the installation site is at or near sea level barometric pressure changes do not affect the percent oxygen readout If ...

Page 47: ...ll position is directly proportional to the original displacement torque and is a linear function of the volume magnetic susceptibility of the sample gas The restoring current is automatically maintained at the correct level by an electro optical feedback system A beam of light from the source lamp is reflected off the square mirror attached to the test body and onto the dual photocell The output ...

Page 48: ...e upstream from the detector and is heated to approximately the same temperature as the detector assembly For convenience in servicing the detector and the optical bench are self aligning assemblies that utilize slip on sample connections and plug in electrical connections Within the detector assembly Figure 4 3B page 4 4 the incoming preheated sample passes through an integral 5 micron diffusion ...

Page 49: ...rque Magnet Platinum Nickel Alloy Suspension Ribbon Balancing Weight Balancing Weight Nitrogen Filled Hollow Glass Test Body Mirror Titanium Wire Conductor TEST BODY DETAIL Electromagnetic Axis Electromagnetic Axis Restoring Current Restoring Current Displacement Torque Restoring Torque CONTROL ASSEMBLY DETECTOR MAGNET ASSEMBLY Test Body Shaded Pole Pieces 4 Source Lamp DS1 Restoring Current Span ...

Page 50: ...Sample Pre Heating Coil Connector J12 Dual Photocell Connector J12 Lamp Retaining Set Screw Photocell Lock Screws 2 Source Lamp Assembly Lamp Viewing Hole Dual Photocell Integral Temperature Sensor RT1 Integral 5 Micron Diffusion Screen Test Body Integral Heater HR2 Mirror Optical Bench Assembly Detector Assembly Source Lamp A Exploded View of Detector Magnet Assembly B Sectional Top View of Optic...

Page 51: ...lectronically controlled heater and associated fan 2 Immediately downstream from the inlet port prior to entry into the detector the sample is preheated by passing through a coil maintained at approximately the same temperature as the detector 3 The detector is maintained at a controlled temperature of 150 F 66 C c Interferents Instrument response to most non oxygen sample components is comparativ...

Page 52: ...ontrol Board and Associated Circuitry The Control Board contains signal conditioning and control circuitry The Control Board is mounted on the inside of the analyzer door see Figure 1 2 on page 1 3 The Control Board contains the following Input Amplifier U1 This amplifier receives the error signal from the dual photocell of the detector assembly and drives amplifier U2 Amplifier U2 and Associated ...

Page 53: ...d crystal display 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 Zero suppression is obtained as the sum of 1 a jumper selectable fixed value of 0 20 40...

Page 54: ... This circuit maintains the interior of the analyzer case at a controlled temperature of 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 d Isolated Current Output Board Optional An isolated current output is obtaina...

Page 55: ...9 quad com parator An understanding of how one of these comparators functions is necessary before any circuit analysis can be attempted In Figure 5 1 on page 5 2 comparators 1 and 2 are depicted having a comparator within an overall comparator symbol Also within this symbol the base of the NPN transistor is connected to the output of the comparator 15VDC is supplied to the emitter The collector is...

Page 56: ...h time the output will be the value of the OR bus As the AC signal goes negative with respect to ground the transistor of comparator 2 conducts and the output is again 15V The output remains at 15VDC until the incoming signal crosses zero value and the positive signal causes the comparator 2 transistor to cease to conduct Summing the effects of the two comparators in the OR circuit results in no o...

Page 57: ...h R78 When the positive potential across C37 and at the inverting terminal of comparator 3 exceeds the potential on the non inverting terminals the transistor conducts The output is 15V A full 30V drop appears across R77 The potential on the non inverting terminal will now be about 2 3V C37 will not discharge through R78 until its potential exceeds that on the non inverting terminal At that time c...

Page 58: ... charge builds up on capacitor C38 The input from the OR comparators 1 and 2 a form of multivibrator circuit pulses 120 times a second For about 100 microseconds the junction of R82 and R83 is some value between 1 85V and 1 92V depending on the ramp generator For this brief period of time one pulse comparator 4 compares the potential of junction R82 R83 with junction RT1 R84 of the bridge circuit ...

Page 59: ...or only part of each ramp and the number of pulses operating Q7 will be proportional to the amount of error sensed by the 6 Hz ramp The pulses arrive at Q7 just as the supply AC line voltage is passing the zero volt crossover point The purpose of C36 Figure 5 2 on 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 a...

Page 60: ...ircuit represents the setpoint value for temperature Suppose that at temperature resistance of the bridge R55 R56 R59 and RT1 equals 149 K 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 ...

Page 61: ... to develop a bias on the base of Q5 through Q4 to the 8 5V bus and back to the secondary As Q5 conducts some of the current going through DS1 is shunted from the main current path and goes through Q5 which acts as a variable feedback resistance goes to the positive output potential of AR7 As DS1 ages its light emission decreases and its resistance increases The current through DS1 tends to decrea...

Page 62: ...ght almost uniformly on each photocell A current proportional to the oxygen concentration in the magnetic field of the test assembly has to be flowing through the feedback loop in order to maintain balance and provide a reading of the oxygen content of the sample Resistances R5 R17 and the resistance of the wire in the feedback loop determine the gain of amplifier AR2 The mirror on the dumbbell is...

Page 63: ...rcuit 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 This signal is ratioed and combined with the negative voltage reference so as to provide a zero based signal at the output of the first amplifier where it is available for measurement and di...

Page 64: ...1 BT1 BT2 FEEDBACK LOOP U4 R16 R5 R17 C1 0022uF 30K R44 200K R9 20K R13 20K 15V 15V 15V 15V DETECTOR COARSE ZERO FRONT PANEL ZERO U2 U6 Vx Vz To Digital and Analog Circuits 10V PRESS SENSOR U7 10V CAL 1 CAL2 U9 R98 R99 To Test Switch To Analog Divider U6 Reference Voltages REFERENCE 10 00V Reference Voltage Circuit R19 TRIM U3 REFERENCE U5 10 00V Figure 5 7 Detector with First Stage Amplifier and ...

Page 65: ...the electronic response time 90 of fullscale and is factory set for 20 seconds 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 The pressure corrected output signal from U10 is routed to two output circuits Digital Output Circuit Section 5 8 on page 5 12 Analo...

Page 66: ... a switch selectable network thus establishing one of six values for amplifier gain DESIRED OXYGEN SPAN FOR RECORDER REQUIRED AMPLIFIER GAIN 100 1X 20 5X 10 10X 5 20X 2 50X 1 100X The desired zero suppression is obtained as the sum of a a jumper selectable fixed value of 0 20 40 or 80 oxygen and b a continuously adjustable value of 0 to 25 oxygen Thus the total zero suppression may be set for any ...

Page 67: ...X 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 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 dri...

Page 68: ...0X 5X 2M To Alarm and V I Amplifier Gain Jumper Selectable Recorder Output Jumper Selectable 20K R50A 20K 1M 200K 100K 20K 2 3 4 Recorder Zero Suppression Jumper Selectable Continuously Variable Recorder Zero Suppression 0 to 25 Oxygen REF REF 20K 75K 17 8K 25K 80 8 33K 60 25K 25K 25K 40 20 1V 100mV 10mV Resistor Values are in Ohms Figure 5 10 Simplified Analog Output Circuit for Recorder Showing ...

Page 69: ...ion of the defective assembly It is recommended that those familiar with circuit analysis refer to the circuit theory in Section 5 of this manual 6 1 INITIAL CHECKOUT WITH STANDARD GASES 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 th...

Page 70: ...etween the orange and red wires The reading should be approximately the same as step 2 If photocell readings not correct replace photocell per Section 1 1a on page 6 7 d Suspension If the suspension has been damaged the cause may by improper operating conditions Maximum permissible operating pressure for the detector is 10 psig 69 kPa gauge pressure To ensure against over pressurization a pressure...

Page 71: ... tubes of the detector assembly 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 6 Seat the detector assembly firmly against the magnet pole pieces and tighten attaching screws 7 Reconnect rubber sample lines to metal inlet and outlet tubes on detector assembly 8 Apply power to instrument and allow to...

Page 72: ...icated by this line Optical Bench 10 J12 1 HR2 Suspension Heater PUR GRN 18 BLK BLK WHT WHT RT1 Suspension Terminals A Connections to Source Lamp and Photocell B Connections to Suspension and Heater Circuits C Removal and Insertion of Pin Leads in Connector J12 Figure 6 1 Detector Magnet Assembly Figure 6 2 Detector Magnet Assembly Wiring Dual Photocell Connector J12 Lamp Retaining Set Screw Photo...

Page 73: ...n the optical bench Carefully remove photocell 6 Loosen lamp retaining set screw remove lamp 7 Note location of lamp wires in connector J12 Disconnect leads of lamp assembly from connector J12 Figure 6 2A on page 6 4 using method shown in Figure 6 2C on page 6 4 Depending on date of manufacture of the analyzer the original lamp assembly may be either of two types Old style lamp assembly with four ...

Page 74: ...ure 6 4 below add straps or solder bridges at the two points shown NOTE If the Connector Board cannot be satisfactorily modified a modified 633689 Connector Board may be ordered from the factory See Section 7 13 Reassemble detector etc in reverse order of disassembly 14 Refer to Figure 6 5 below The red line on the lamp must be aligned with the retaining set screw Insert lamp into mounting hole un...

Page 75: ...F3 are to be plugged in never soldered If soldered the fuse element may melt and open the circuit a Case Heater Control Circuit The case heater control circuit receives power via thermal fuse F2 76 C This fuse located on the Case Board can be checked for continuity Case heater element HR3 located on the heater fan assembly has a normal resistance of 20 ohms To verify heater operation place a hand ...

Page 76: ...ould be approximately 89 ohms If resistance the resistance of HR2 is correct and yet the combined resistance is incorrect heater HR1 may be open To reach the leads of HR1 remove the printed circuit board on the heater assembly Resistance of HR1 should be approximately 21 ohms To check operation of the heater circuit connect a voltmeter across R61 on the Case Board Normally the voltage will be 4 VD...

Page 77: ...nt of the individual component The cost of test and replacement will exceed the cost of a rebuilt assembly As standard policy rebuilt boards are available on an exchange basis Because of the exchange policy covering circuit boards the following list does not include individual circuit board mounted components If circumstances necessitate replacement of an individual component which can be identifi...

Page 78: ...f 1 2 5 10 20 50 or 100 using any zero offset 2 0 0 100 Oxygen on Display Recorder Output span of 5 or greater for zero based ranges 9 Special Code Corrosion Resistance 1 Standard detector 2 Detector with rhodium plated current loop 2 3 Detector with stainless steel tubing 3 4 Detector with rhodium plated current loop and stainless steel tubing 09 Special Code Output 01 Voltage 0 10 mV 0 100 mV 0 ...

Page 79: ...ipment 4 Enclose a cover letter and purchase order and ship the defective equipment according to instructions provided in the Rosemount Return Authorization prepaid to the address provided by Rosemount CSC Rosemount Analytical Inc Process Analytical Division Customer Service Center 1 800 433 6076 If warranty service is expected the defective unit will be carefully inspected and tested at the facto...

Page 80: ...Instruction Manual 245364 V May 2002 8 2 Return of Material Rosemount Analytical Inc A Division of Emerson Process Management Model 755A ...

Page 81: ...d balanced bridge at 1 atmosphere input configuration A Bridge Balance pot on the Vaisala Interface Circuit board provides the fine trim Bridge Balancing calibration adjustment that is required to set up each individual transducer at a known ambient air pressure Test points are provided on the circuit board for this adjustment An adjustable precision regulated voltage divider consisting of R1 R2 V...

Page 82: ...his same board 2 Move the DVM to TP 14 and ground TP10 Adjust the AD625 zero offset adjustment for the lowest zero voltage output Note All these adjustments are made at ambient pressure and the display on position 2 should now read zero The noise should be less than 1 count Procedure is complete A 5 HIGH ALTITUDE VERSION OPTION For applications where the instrument is to be used above 5400 Feet MS...

Page 83: ...rectly or indirectly arising from the use of the equipment or goods from breach of any warranty or from any other cause All other warranties expressed or implied are hereby excluded IN CONSIDERATION OF THE HEREIN STATED PURCHASE PRICE OF THE GOODS SELLER GRANTS ONLY THE ABOVE STATED EXPRESS WARRANTY NO OTHER WARRANTIES ARE GRANTED INCLUDING BUT NOT LIMITED TO EXPRESS AND IMPLIED WARRANTIES OR MERC...

Page 84: ...ingapore Private Ltd 1 Pandan Crescent Singapore 128461 Republic of Singapore T 65 777 8211 F 65 777 0947 http www processanalytic com Fisher Rosemount GmbH Co Industriestrasse 1 63594 Hasselroth Germany T 49 6055 884 0 F 49 6055 884209 EUROPE MIDDLE EAST AFRICA Fisher Rosemount Ltd Heath Place Bognor Regis West Sussex PO22 9SH England T 44 1243 863121 F 44 1243 845354 LATIN AMERICA Fisher Rosemou...

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