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T

HEORY

748213-P Rosemount Analytical June 1997

5-7

Model 755R Oxygen Analyzer

Potentiometric output is strap-selectable for 0 to 10 mV, 0 to 100 mV, 0 to 1 V, or 0 to
5VDC. Potentiometer R88 permits adjustment of recorder span on 0 to 1 V, 100 mV
and 10 mV outputs.

5.3.3 P

OWER

S

UPPLY

B

OARD

A

SSEMBLY

The Power Supply Board assembly contains power supply and temperature control
circuitry. The assembly is mounted within the analyzer case.

As shown in DWG 617186, the various circuits operate on main power transformer T1.
During instrument assembly, the two primary windings of T1 are factory-connected for
operation on either 115 VAC or 230 VAC, as noted on the name rating plate.

The same circuit board contains the following:

S

OURCE

L

AMP

P

OWER

S

UPPLY

S

ECTION

This circuit provides a regulated output of 2.20 VDC to operate incandescent source
lamp DS1 within the optical bench assembly. One secondary of main power
transformer T1 drives a fullwave rectifier consisting of CR7 and CR8. The output of
DS1 is held constant by a voltage regulator circuit utilizing U7, Q4 and Q5.

T

HE

±±±±

15 V P

OWER

S

UPPLY

S

ECTION

This section provides DC voltage required for various amplifiers and other circuits.

Fullwave rectifier bridge CR5 provides both positive and negative outputs. Each is
routed through an associated series type integrated circuit, voltage regulator, providing
regulated outputs of +15 V and -15 V.

D

ETECTOR

T

EMPERATURE

C

ONTROL

S

ECTION

This section 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. The signal from the sensor is applied to amplifier AR6, which
drives transistors Q2 and Q3, thus controlling application of DC power from full wave
rectifier bridge CR6 to two heaters within the detector/magnet assembly: HR1,
mounted on the top of the magnet and HR2, permanently mounted on the rear of the
detector assembly.

D

ETECTOR

C

OMPARTMENT

T

EMPERATURE

C

ONTROL

S

ECTION

This section maintains the interior of the detector compartment at a controlled
temperature of 140

°

F (60

°

C). Temperature is sensed by a thermistor located in the

detector compartment and plugged into the Control Board assembly.

The circuit provides an on-off control of heater element HR3 via TRIAC element Q7.
Heater HR3 is a part of the heater/fan assembly.

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Содержание 755R

Страница 1: ...Rosemount Analytical MODEL 755R OXYGEN ANALYZER INSTRUCTION MANUAL ...

Страница 2: ...48213 P June 1997 Printed in U S A Rosemount Analytical Inc 4125 East La Palma Avenue Anaheim California 92807 1802 Paliney No 7 is a trademark of J M Ney Co Hartford CT Viton A is registered a trademark of E I duPont de Nemours and Co Inc Teflon is a registered trademark of E I duPont de Nemours and Co Inc ...

Страница 3: ...L ASSISTANCE AND FIELD SERVICE P 5 RETURNING PARTS TO THE FACTORY P 5 TRAINING P 5 DOCUMENTATION P 5 COMPLIANCES P 6 SECTION 1 INTRODUCTION 1 1 DESCRIPTION 1 1 1 2 RECORDER OUTPUT RANGE 1 2 1 3 MOUNTING 1 2 1 4 ISOLATED CURRENT OUTPUT 1 2 1 5 ALARM OPTION 1 2 1 6 ELECTRICAL OPTIONS 1 2 1 7 REMOTE RANGE CHANGE OPTION 1 2 SECTION 2 INSTALLATION 2 1 FACILITY PREPARATION 2 1 2 1 1 Installation Drawing...

Страница 4: ... Recorder Output Selection and Cable Connections 2 8 2 4 2 1 Potentiometric Output 2 8 2 4 2 2 Isolated Current Output Optional 2 9 2 4 3 Output Connections and Initial Setup for Dual Alarm Option 2 10 2 5 REMOTE RANGE CHANGE OPTION 2 14 SECTION 3 STARTUP AND CALIBRATION 3 1 OVERVIEW 3 1 3 2 OPERATING RANGE SELECTION 3 1 3 3 STARTUP PROCEDURE 3 1 3 4 CALIBRATION 3 1 3 4 1 Calibration with Zero and...

Страница 5: ...IRCUIT 6 1 6 4 DETECTOR HEATER CONTROL CIRCUIT 6 6 6 5 DETECTOR LIGHT SOURCE CONTROL CIRCUIT 6 7 6 6 DETECTOR WITH FIRST STAGE AMPLIFIER 6 8 6 7 BUFFER AMPLIFIERS U8 U10 WITH ASSOCIATED ANTICIPATION FUNCTION 6 11 6 8 DIGITAL OUTPUT CIRCUIT 6 11 6 9 ANALOG OUTPUT CIRCUITS FOR RECORDER ALARMS 6 12 6 9 1 First Stage Amplifier 6 12 6 9 2 Second Stage Amplifier 6 12 SECTION 7 SERVICE AND MAINTENANCE 7 ...

Страница 6: ... 4 1 Source Lamp 7 6 7 4 2 Photocell 7 6 7 4 3 Detector 7 8 7 5 CONTROL BOARD SETUP 7 9 SECTION 8 REPLACEMENT PARTS 8 1 CIRCUIT BOARD REPLACEMENT POLICY 8 1 8 2 SELECTED REPLACEMENT PARTS 8 1 GENERAL PRECAUTIONS FOR HANDLING STORING HIGH PRESSURE CYLINDERS WARRANTY FIELD SERVICE AND REPAIR FACILITIES ...

Страница 7: ...ector Magnet Assembly 5 5 6 1 Two Comparator OR Circuit 6 3 6 2 Case Heater Control Circuit 6 3 6 3 Ramp Generator Circuit 6 4 6 4 Detector Heater Control Circuit 6 7 6 5 Detector Light Source Control Circuit 6 8 6 6 Detector with First Stage Amplifier 6 10 6 7 Buffer Anticipation and Digital Output Circuits 6 11 6 8 Simplified Analog Recorder Output Circuit 6 13 7 1 Detector Magnet Assembly 7 4 7...

Страница 8: ...CONTENTS vi June 1997 Rosemount Analytical 748213 P Model 755R Oxygen Analyzer NOTES ...

Страница 9: ... cause severe personal injury death or substantial property damage if the warning is ignored WARNING is used to indicate the presence of a hazard which can cause severe personal injury death or substantial property damage if the warning is ignored CAUTION is used to indicate the presence of a hazard which will or can cause minor personal injury or property damage if the warning is ignored NOTE is ...

Страница 10: ...ct Use only factory documented components for repair This analyzer requires periodic calibration with known zero and standard gases Refer to Sections 2 2 and 2 3 See also General Precautions for Handling and Storing High Pressure Cylinders following Section 7 This instrument s internal pullout chassis is equipped with a safety stop latch located on the left side of the chassis When extracting the ...

Страница 11: ...ange over entire range SPAN DRIFT 1 fullscale per 24 hours provided that ambient temperature does not change by more than 20 F 11 1 C 2 5 of fullscale per 24 hours with ambient temperature change over entire range SPECIFICATIONS SAMPLE DRYNESS Sample dewpoint below 110 F 43 C sample free of entrained liquids TEMPERATURE LIMITS 50 F 10 C to 150 F 65 C OPERATING PRESSURE Maximum 10 psig 68 9 kPa Min...

Страница 12: ...current output of 0 to 20 mA or 4 to 20 mA is obtainable through plug in of optional circuit board OPTIONAL ALARMS High and low independently adjustable alarms Form C contact ratings ALARM CONTACT RATINGS 5 A 240 VAC resistive 5 A 120 VAC resistive 5 A 28 VDC resistive SETPOINT Adjustable from 1 to 100 fullscale DEADBAND Adjustable from 1 to 20 fullscale Factory set to 10 of fullscale SPECIFICATIO...

Страница 13: ...Unauthorized returns will be returned to the sender freight collect When returning any product or component that has been exposed to a toxic corrosive or other hazardous material or used in such a hazardous environment the user must attach an appropriate Material Safety Data Sheet M S D S or a written certification that the material has been decontaminated disinfected and or detoxified Return to R...

Страница 14: ...ACE P 6 June 1997 Rosemount Analytical 748213 P Model 755R Oxygen Analyzer COMPLIANCES This product satisfies all obligations of all relevant standards of the EMC framework in Australia and New Zealand N96 ...

Страница 15: ...anel digital display In addition a field selectable voltage output is provided as standard An isolated current output of 0 to 20 mA or 4 to 20 mA is obtainable through plug in of an optional circuit board Current and voltage outputs may be utilized simultaneously if desired An alarm option is also available by way of a relay assembly that mounts at the rear of the case with a cable that plugs into...

Страница 16: ...ad of 1000 ohms 1 5 ALARM OPTION The alarm option contains An alarm circuit incorporating two comparator amplifiers one each for the ALARM 1 and ALARM 2 functions Each amplifier has associated setpoint and deadband adjustments Setpoint is adjustable from 1 to 100 of fullscale Deadband is adjustable from 1 to 20 of fullscale An alarm relay assembly containing two single pole double throw relays one...

Страница 17: ...ous weather protected area Permissible ambient temperature range is 32 F to 113 F 0 C to 45 C Avoid mounting where ambient temperature may exceed the allowable maximum Magnetic susceptibilities and partial pressures of gases vary with temperature In the Model 755R temperature induced readout error is avoided by control of temperatures in the following areas 1 Interior of the analyzer is maintained...

Страница 18: ...th the manufacturer s instructions Refer to GENERAL PRECAUTIONS FOR HANDLING STORING HIGH PRESSURE CYLINDERS at the rear of this manual Analyzer calibration consists of establishing a zero calibration point and a span calibration point Zero calibration is performed on the range that will be used during sample analysis In some applications however it may be desirable to perform span calibration on ...

Страница 19: ...er range limit If this range limit is 21 or 25 oxygen the usual span standard gas is air 20 93 oxygen 2 3 SAMPLE HANDLING Basic requirements for sample handling are 1 A 2 micron particulate filter inserted into the sample line immediately upstream from the analyzer inlet 2 Provision for pressurizing the sample gas to provide flow through the analyzer 3 Provision for selecting sample zero standard ...

Страница 20: ... the detector and will void the warranty The basic rule for pressure of sample and standard gases supplied to the inlet is to calibrate the analyzer at the same pressure that will be used during subsequent operation and to maintain this pressure during operation The arrangement required to obtain appropriate pressure control will depend on the application When inputting sample or calibration gases...

Страница 21: ...used in certain special applications A suction pump is connected to the analyzer exhaust port to draw sample into the inlet and through the analyzer Such operation necessitates special precautions to ensure accurate readout First is the basic consideration of supplying the standard gases to the analyzer at the same pressure that will be used for the sample during subsequent operation In addition a...

Страница 22: ...s steel glass titanium Paliney No 7 epoxy resin Viton A platinum nickel and MgF2 coating on mirror 2 3 7 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 2 3 8 LEAK TEST The sample containment system must be carefu...

Страница 23: ...ower G TB2 Customer hook up for Recorder Output H Optional Dual Alarm connections I Connections for Optional Remote Range Change FIGURE 2 2 MODEL 755R REAR PANEL 2 4 ELECTRICAL CONNECTIONS For safety and proper performance this instrument must be connected to a properly grounded three wire source of supply Cable connections for AC power recorder output and alarm output are shown in Installation Dr...

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

Страница 25: ...ard appropriate to desired output is properly in place in its connector See Figure 3 1 If originally ordered with the analyzer the board is factory installed 2 On I O board connect leads of shielded recorder cable to CURRENT OUT and terminals 3 Connect free end of output cable to input terminals of recorder or other current actuated device making sure that polarity is correct If two or more curren...

Страница 26: ...m Indicator Fail Safe High Control Fail Safe Solenoid Valve N H 115 VAC 2 4 3 OUTPUT CONNECTIONS AND INITIAL SETUP 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 654019 Alarm Kit The alarm output provides two sets of relay contacts for actuation of alarm and or process control fu...

Страница 27: ...adband The Alarm 2 relay coil is de energized when the display moves upscale through the value that corresponds to the setpoint plus deadband This relay coil is energized when the display moves downscale through the value that corresponds to setpoint minus deadband Both the ALARM 1 and ALARM 2 functions generally incorporate automatic rest When the display goes beyond the pre selected limits the c...

Страница 28: ...t at 100 i e position 10 on dial adjust front panel SPAN Control so that the display or recorder reads exactly fullscale b Set ALARM 1 Calibrate Adjustment R63 to its clockwise limit Carefully rotate R63 counterclockwise the minimum amount required to obtain energization of ALARM 1 Relay K1 See Figures 2 6 and 3 1 Energization may be verified by connecting an ohmmeter to relay terminals on 654019 ...

Страница 29: ...g continuity between the common and normally open contacts of the relay When input signal moves upscale through this point the coil of ALARM 2 relay K2 is energized providing continuity between the common and normally closed contacts of the relay A Typical ALARM 1 Setting DEADBAND SET FOR 20 OF FULLSCALE DEADBAND SET FOR 10 OF FULLSCALE B Typical ALARM 2 Setting INPUT SIGNAL Percent of Fullscale I...

Страница 30: ...ly the external 12 V to J3 5 3 Program the remote controller to pull the range bits J3 1 through J3 4 low See truth table below To use the internal 12 V supply 1 Verify the E to F jumper is in place 2 Connect the controller s common to J3 6 to reference the instrument s common to the controller s common DO NOT connect anything to J3 5 3 Connect J3 1 to J3 4 as shown in the truth table below to swi...

Страница 31: ... not actual sample through the analyzer Turn power ON If digital display gives overrange indication the probable cause is the suspension in the detector is hung up To correct this condition turn power OFF tap detector compartment with fingers wait 30 seconds turn power ON When on scale reading is obtained allow analyzer to warm up for a minimum of one hour with gas flowing This warm up is necessar...

Страница 32: ...ge analyzer for a minimum of three minutes Adjust SPAN control so that reading on display or recorder is appropriate to the span standard gas 3 5 COMPENSATION FOR COMPOSITION OF BACKGROUND GAS Any gas having a composition other than 100 oxygen contains background gas The background gas comprises all non oxygen constituents Although instrument response to most gases other than oxygen is comparative...

Страница 33: ...M 2 SETPOINT R68 Continuously variable adjustment of setpoint for ALARM 2 circuit for actuation of external customer supplied control device s Adjustment range is 0 to 100 of fullscale span 11 ALARM 2 DEADBAND R78 Adjustment of ALARM 2 deadband circuit from 1 to 20 of fullscale Deadband is essentially symmetrical with respect to setpoint 12 ALARM 1 CALIBRATION R63 Initial calibration of ALARM 1 ci...

Страница 34: ... Table 3 2 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 2 if analyzer response to oxygen is 100 the response to xenon would be 1 34 The oxyg...

Страница 35: ...ections are to be made the zero standard span standard and sample gases must all be admitted at the same pressure Use the following equation to compute the adjusted settings for the ZERO and SPAN controls Adjusted O2 for standard gas Where A true O2 of standard gas B BGGs C BGGst Example Background gas in sample is CO2 oxygen equivalent 0 623 Zero gas is 100 N2 Span standard gas is air 21 O2 79 N2...

Страница 36: ...2 0 117 Allene C3H4 0 744 Hydrogen Bromide Hbr 0 968 Ammonia NH3 0 479 Hydrogen Chloride HC1 0 651 Argon A 0 569 Hydrogen Fluoride HF 0 253 Bromine Br2 1 83 Hydrogen Iodide HI 1 403 1 2 Butadiene C4H6 1 047 Hydrogen Sulphide C2S 0 751 1 3 Butadiene C4H6 1 944 Kryton Kr 0 853 n Butane C4H10 1 481 Methane CH4 0 512 iso Butane C4H10 1 485 Neon Ne 0 205 Butene 1 C4H8 1 205 Nitric Oxide NO 44 2 cis But...

Страница 37: ...xample Operating range 0 to 5 oxygen Desired ALARM 1 setpoint 4 oxygen Turn potentiometer R64 to 8 Desired ALARM 2 setpoint 3 oxygen Turn potentiometer R68 to 6 The desired deadband may be selected via the appropriate trimming potentiometer R73 for ALARM 1 deadband adjustment and R78 for ALARM 2 deadband adjustment For any setpoint deadband is adjustable from 1 of fullscale counterclockwise limit ...

Страница 38: ...8 9 10 Percentage Oxygen Readout Setpoint Dial Reading 0 2 5 5 7 5 10 12 5 15 17 5 20 22 5 25 0 1 2 3 4 5 6 7 8 9 10 Percentage Oxygen Readout Setpoint Dial Reading 0 5 10 15 20 25 30 35 40 45 50 0 1 2 3 4 5 6 7 8 9 10 Percentage Oxygen Readout Setpoint Dial Reading 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 Percentage Oxygen Readout Setpoint Dial Reading 0 0 0 5 1 0 1 5 2 0 2 5 3 0 3...

Страница 39: ...barometric pressure changes do not affect the percent oxygen readout However if the analyzer exhaust port is vented directly to the atmosphere any change in barometric pressure after instrument standardization will result in a directly proportional change in the indicated percentage of oxygen This effect may be compensated in various ways If desired correction may be made by the following equation...

Страница 40: ... the particular application and is best determined by keeping a calibration log If the analyzer exhaust port is vented directly to the atmosphere the greatest source of error is normally the variation in barometric pressure If desired effects of barometric pressure variation can be minimized by calibrating immediately before taking readings for example at the beginning of each shift ...

Страница 41: ...ement torque is opposed by an equal but opposite restorative torque The restorative torque is due to electromagnetic forces on the spheres resulting from a feedback current routed through a titanium wire conductor wound lengthwise around the dumbbell In effect each sphere is wound with a one turn circular loop The current required to restore the test body to null position is directly proportional ...

Страница 42: ...nce assume that an instrument is calibrated for correct readout with a standard gas containing 5 oxygen admitted at the normal sea level atmospheric pressure of 14 7 psia 101 3 kPa If the operating pressure now drops to one half the original value i e to 7 35 psia 50 65 kPa and the calibration controls are left at the previously established settings the display reading for the standard gas will dr...

Страница 43: ...kel 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 Zero Dual Photocell BT1 ...

Страница 44: ...r reflects the beam onto dual photocell BT1 BT2 The difference between the signals developed by the two halves of the photocell constitutes the error signal supplied to the input of amplifier U1 on the Control Board assembly Amplifier U1 drives U2 which in turn supplies the restoring current to the titanium wire loop on the test body See Section 5 1 Detector temperature is sensed by thermistor RT1...

Страница 45: ...cal Bench Assembly Detector Assembly Source Lamp B Sectional Top View of Optical Bench and Detector Assemblies Detector Assembly Mounting Screws 2 Optical Bench Assembly Magnet Assembly Sample Outlet Tube Sample Inlet Tube Sample Pre Heating Coil A Exploded View of Detector Magnet Assembly Connector J12 Dual Photocell Connector J12 Lamp Retaining Set Screw Photocell Lock Screws 2 Source Lamp Assem...

Страница 46: ...factor Adjustment range is approximately 30 AMPLIFIER U8 This unity gain amplifier provides zeroing capability and a buffered output for the anticipation circuit feeding U10 AMPLIFIER U10 U10 is an inverting buffer amplifier that incorporates an anticipation arrangement in its input network thus providing slightly faster response on the readout device s Potentiometer R30 provides a continuously va...

Страница 47: ...d Q5 THE 15 V POWER SUPPLY SECTION This section provides DC voltage required for various amplifiers and other circuits Fullwave rectifier bridge CR5 provides both positive and negative outputs Each is routed through an associated series type integrated circuit voltage regulator providing regulated outputs of 15 V and 15 V DETECTOR TEMPERATURE CONTROL SECTION This section maintains the detector at ...

Страница 48: ...nalyzer 5 3 4 ISOLATED CURRENT OUTPUT BOARD OPTIONAL An isolated current output is obtainable by insertion of an optional plug in circuit board into receptacle J1 on the Control Board see Figure 3 1 The current outputs available by this board are 0 to 20 mA or 4 to 20 mA ...

Страница 49: ...the Power Supply Board 19 VAC should be measured with respect to ground at CR5 WO4 15 VDC should be measured at the C27 lead and 15 VDC at the C28 lead If the specified voltage measurements are obtained the power supply is working correctly 6 3 CASE HEATER CONTROL CIRCUIT The case heater control circuit utilizes four voltage comparators LM339 quad com parator An understanding of how one of these c...

Страница 50: ...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 output from the comparators for about 4 of the sine wave 2 after the signal goes positive 0 to 2 and 2 before the positive signal reaches 180 178 to 180 During the period that neither comparator is conducting th...

Страница 51: ... 7V ON ON OFF OFF OFF ON COMP 1 COMP 2 FIGURE 6 1 TWO COMPARATOR OR CIRCUIT FIGURE 6 2 CASE HEATER CONTROL CIRCUIT 120 V RMS T1 19 VAC TO POWER SUPPLY 19 VAC 12 R67 10K R72 4 75K C36 18uF CR10 CR9 15V R71 21 5K R69 2 M R68 3 3K R70 20M R73 20M R74 590K 15V 1 2 3 4 R75 210K R85 11 0K R86 20M R76 37 4K C40 2200uF C37 1 0uF C39 01uF R83 63 4K R84 169K R82 9 07K RT1 15V Q6 R80 10K R79 10K R81 56 2 C38...

Страница 52: ... potential at the top of the bridge circuit between R82 and R83 through R74 Because of the ramp action charging and discharging C37 the potential between R82 and R83 varies approximately from 1 85 V to 1 92 VDC The temperature sensing device RT1 in the bridge circuit is a thermistor The bridge is designed to control the temperature in the case at 135 F 57 C When the temperature is 135 F 57 C the r...

Страница 53: ... time one pulse comparator 4 compares the potential of junction R82 R83 with junction 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 15 V The base of Q6 is zero because of the voltage drops across R79 and R80 Therefore Q6 conducts Energy stored in C38 flows through Q6 as current and capac...

Страница 54: ... RT1 in the resistance bridge varies inversely with temperature 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 and increases rapidly as the temperature decreases R59 in this bridge circuit...

Страница 55: ...1 to ground and from ground through DS1 for an input voltage to terminal 2 of AR7 through R66 to develop a bias on the base of Q5 through Q4 to the 8 5 V 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...

Страница 56: ...fer to Figure 6 6 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 Around the test body a titanium wire is chemically etched in order to form a feedback loop that can create a counteracting magnetic...

Страница 57: ... the dumbbell is positioned by the amount of current in the feedback loop The mirror reflects light from the source DS1 to the photocells BT1 BT2 This repositioning of the mirror is a form of mechanical feedback to the input of the amplifier U1 The net result is that the output of U1 could vary from 0 to 70 mV or 0 to 7 0 V depending on the range of the instrument R4 C3 and R5 C7 form damping circ...

Страница 58: ...omes more positive When it exceeds that on the anode CR2 ceases to conduct and isolates the 15 VDC and 15 VDC power supply from the input circuit The front panel zero potentiometer R13 and detector coarse zero potentiometer add or subtract current to the input of U2 to offset any currents that may occur because of any imbalance in the detector and the photocells BT1 and BT2 The output current that...

Страница 59: ...gain of 10 is provided by the feedback network associated with U10 to restore the signal to the desired fullscale range of 0 to 10 VDC The output signal from U10 is routed to two output circuits Digital output circuit See Section 6 8 Analog output circuits for recorder V I and alarms See Section 6 9 6 8 DIGITAL OUTPUT CIRCUIT Refer to Figure 6 7 The output signal from buffer amplifier U10 is route...

Страница 60: ... Output Resistor Network It provides a jumper selectable output of 0 to 10 mV 0 to 100 mV 0 to 1 V or 0 to 5 VDC 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 654019 Alarm Relay Assembly Oxygen is strongly paramagnetic while most other common gases are weakly ...

Страница 61: ...IRCUIT R84 20K C46 1uF TP18 R88 500 To Recorder U13 FROM U10 1 2 5 5 50 R85 2M 100 U16 1V R57 3 83K E3 E4 5V E1 E2 R58 909 E5 E6 R59 90 9 E7 E8 100mV 10mV R60 10 C55 1uF R102 40K 10 25 R86 80K R52 200K R87 400K R53 800K R82 2M To Alarm and V I Recorder Span Jumper Selectable Recorder Output Jumper Selectable R50C 20K R50B 20K R50A 20K ...

Страница 62: ...CIRCUIT ANALYSIS 6 14 June 1997 Rosemount Analytical 748213 P Model 755R Oxygen Analyzer NOTES ...

Страница 63: ... instrument must be connected to a properly grounded three wire source of power Optional alarm switching relay contacts wired to separate power sources must be disconnected before servicing Tampering or unauthorized substitution of components may adversely affect safety of this product Use only factory documented components for repair 7 1 INITIAL CHECKOUT WITH STANDARD GASES If instrument readings...

Страница 64: ...ve and must be replaced verify correct operation of all circuits that could cause erratic readings 7 1 1 CONTROL BOARD CHECKOUT The Detector Isolation Plug Figure 3 1 located on the Control Board removes the detector signal allowing the input voltage to go to zero The display should register near zero or on scale and TP20 should read zero voltage To test the remainder of the measuring circuit do t...

Страница 65: ...fully place a hand on top of detector compartment Heat should be felt If not check the case heating circuit Temperature sensor RT1 has a cold resistance of 22 7K ohms and a normal operating resistance of 20 2K ohms indicating normal operating temperature As a further check disconnect plug P6 on the Control Board thus disconnecting temperature sensor RT1 Substitute a decade resistor box to simulate...

Страница 66: ...operating temperature of 65 C FIGURE 7 1 DETECTOR MAGNET ASSEMBLY 7 3 DETECTOR CHECK To isolate the detector as the problem it is necessary to check the source lamp photocells and suspension see Figure 7 1B These components are connected via J12 on the optical bench assembly Pin leads may be removed from connector J12 by use of an improvised pin removal tool such as a paper clip see Figure 7 2 Con...

Страница 67: ...OURCE LAMP The simplest check of the source lamp is to verify that it is lit Another check is done by removing the housing cover and viewing the lamp through the photocell alignment hole see Figure 7 3 If the photocell is not illuminated test the voltage across TP2 to TP5 ground This voltage should be 2 2 V 0 2 VDC If reading is correct the lamp may be burned out also inspect the cable for continu...

Страница 68: ...suspension has been damaged and detector assembly must be replaced See Section 7 4 3 If the suspension has been changed the cause may be improper operating conditions 7 4 REPLACEMENT OF DETECTOR MAGNET COMPONENTS 7 4 1 SOURCE LAMP REMOVAL INSTALLATION The source lamp is held in the optical bench assembly by a set screw see Figure 7 1B The two lamp leads are connected to J12 The red line on the lam...

Страница 69: ...ocell to obtain a DC voltage as close to 0 mV as possible but no more than 750 mV Apply power to instrument and allow to warm up approximately one hour Set front panel ZERO at mid range i e five turns from either end Connect digital voltmeter from slider of R9 to chassis ground With a steady flow of 50 to 500 cc min of nitrogen zero gas going through instrument adjust R9 for 0 V Connect the voltme...

Страница 70: ...t tubes of the detector assembly 4 Remove the two screws at the bottom of the detector assembly slide detector out INSTALLATION 1 Install replacement detector assembly and connect cable to J12 2 Seat the detector assembly firmly against the magnet pole pieces and tighten attaching screws 3 Reconnect rubber sample lines to metal inlet and outlet tubes on detector assembly 4 Apply power to instrumen...

Страница 71: ...er 5 Measure TP19 5 VDC 0 25 VDC DETECTOR ZERO 1 Flow 250 cc min nitrogen 2 Monitor TP8 adjust R9 for 0 VDC 2mV U4 ZERO 1 Monitor TP5 adjust R100 for 1 VDC 2mV 2 Monitor TP10 adjust R13 ZERO for 0 0 VDC 5mV U8 ZERO Monitor TP11 adjust R29 for 0 0 VDC 5mV U10 ZERO 1 Monitor TP16 adjust R29 for 0 0 VDC 5mV Note This adjustment requires a long time constant Allow adequate time 2 Adjust R29 to obtain ...

Страница 72: ... P Model 755R Oxygen Analyzer RECORDER FULLSCALE 1 Flow nitrogen at 250 cc min monitor TP16 and adjust front panel ZERO potentiometer for 000 VDC 2 Flow 100 oxygen for span gas Recorder output for 1 V 100 mV or 10 mV should read 100 of span gas Adjust R88 if necessary ...

Страница 73: ...ce the board than to attempt isolation and replacement 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 replacem...

Страница 74: ...RIPTION 631773 Power Supply Board 652830 Control Board Kit 654004 Thermistor Case Heater 654022 Display Assembly 654078 Viton Tubing Sample In 654079 Viton Tubing Sample Out 654080 Fan Heater 654081 Case Heater 809374 Fuse 3 4A Power Transformer 115VAC 860371 Alarm Relay 861467 Shock Mount Package of 4 ...

Страница 75: ... 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 ...

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Страница 77: ... 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 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE Limitations of Remedy SELLER SHALL NOT BE LIAB...

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Страница 79: ...r Please have the following information when you call Model Number Serial Number and Purchase Order Number or Sales Order Number Prior authorization by the factory must be obtained before returned materials will be accepted Unauthorized returns will be returned to the sender freight collect When returning any product or component that has been exposed to a toxic corrosive or other hazardous materi...

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