DIFFERENTIAL PRESSURE NULL TRANSDUCER
Contents
1. B 1 LIST OF FIGURES FIGURE 7 1 2413 711 DIFFERENTIAL PRESSURE NULL INDICATOR 7 2 FIGURE 7 2 2413 711 DIFFERENTIAL PRESSURE NULL INDICATOR VIEW 7 3 viii INTRODUCTION SECTION 1 0 DESCRIPTION AND SPECIFICATIONS 1 1 GENERAL DESCRIPTION The Differential Pressure Null Detector composed of a Differential Pressure Transducer 2413 or 2417 and Electronic Null Indicator 2416 is designed to sense small pressure differences in both low and high pressure systems The transducer consists of two pressure chambers separated by a thin diaphragm A difference in pressure in the two chambers causes a deflection of the diaphragm and a resultant signal to the electronic circuit The signal is obtained as the output of a differential transformer whose movable core is attached to the diaphragm The signal is not a linear function of the difference in pressure therefore use of the instrument for accurate evaluation of pressure differences is limited to small deflections of the diaphragm The principle use of the instrument is intended as a null sensor indicator with which the pressure of one medium may be precisely adjusted to that of another Some of the advantages of the instrument are its high sensitiveness high working pressure 15 000 psi for 2413 Series cells and 40 000 psi for 2417 Series and its ability to withstand the full working pressure across the diaphragm without injury 15 000 ps2. uu 2 1 SECTION 3 0 PREPARATION FOR USE Bell PREPARATION FOR USE uu uu u u amahuani T Ar UA 3 1 3 2 BLEEDING LOWER CHAMBER IN A LIQUID TO LIQUID SYSTEM 3 2 SECTION 4 0 OPERATION 41 OPERATING INSTRUCTIONS SHE Re ent 4 1 SECTION 5 0 PERFORMANCE OBSERVATIONS 5 1 ACTUAL SENSITIVITY VERSUS APPARENT 5 525 CALIBRATION S echas L tont ede are mae Eb SE 5 2 9 2 DETECTING LEAKS a eR Ro RAM 5 2 SECTION 6 0 MAINTENANCE 6 1 SERVICING THE INSTRUMENT ae perdet efi nes 6 1 6 2 DIAPHRAGM ee s Cabe urs Los 6 1 6 2 1 Replacement of Diaphragm in Model 2413 Transducer 6 1 6 3 REPLACEMENT OF DIFFERENTIAL TRANSDUCER IN THE 2413 D NULL INDICATOR eee abt e ne Du pp 6 3 6 3 I Failure Didgnoses a Ecos 6 4 6 4 REPLACEMENT OF TRANSFORMER 6 4 SECTION 7 0 PARTS LIST SECTION 8 0 INTRODUCTION INTRODUCTION 2 2a 8 1 SECTION 9 0 FUNCTIONAL CIRCUIT DESCRIPTION 9 1 FUNCTIONAL CIRCUIT DESCRIPTION tri eit taken 9 SECTION 10 0 TEST PROCEDURE STESEPROGEDURF aan 10 1 vii INTRODUCTION APPENDIX A EXPLANATION OF TEST REPORT 1 APPENDIX B DRAWINGS AND 5
3. U TYPE 2 000 EACH 0010 75 105 SOLDER MULTICORE SN 60 22 1 0 001 EACH 0011 16 81 PWER CORD IEC USA 10A 2 4 M 1 000 EACH 0014 186 814 TBG PVC 105 BLK 066 IDX 016W 0 420 FOOT 0015 161 597 PLUG PHONE TYPE 5250 1 000 EACH 0016 70 130 401 BUHMS 6 32 X 1 2 SS 2 000 EACH 0017 191 217 WIL 0 150 X 0 295 X 021 6 SS 4 000 EACH 0018 53 304 NUT 6 32 FHFN 2 000 EACH APPENDIX B 2416
4. RELEASE 2413 1D00 REVISION A unknown Original release RELEASE 2413 1D00 REVISION B 09 30 90 Updated to new manual format RELEASE 2413 1D00 REVISION C 05 12 92 Page 7 4 corrected part no 2413 021 to 2413 023 ECO 18024 RELEASE 2413 1D01 REVISION D 06 27 02 Combined 2413 and 2416 manuals to form 2413 1001 Revision D See DC RO 23407 INTRODUCTION WARNING THE CONTROL BOX NULL INDICATOR MUST BE SET FOR THE PROPER LINE VOLTAGE PRIOR TO CONNECTION TO A POWER SOURCE vi INTRODUCTION TABLE OF CONTENTS WARRAN liege e quete o pe ON ERE ii COPYRIGHT NOTICE DISCLAIMER TRADEMARK iii REVISION NOTICE tend iv REVISION HISTORY rer RO E DR UR de to m uu EPA d WARNING La l re vi TABBE OP CORBTEBNTIS bb e tese ad et deu ba ode Urdu SECTION 1 0 DESCRIPTION AND SPECIFICATIONS I gt GENERAL DESCRIPTION sn costa n RA E ERR DE Nd d va 1 1 122 SPECIFICATIONS d asc uut a E reete Pad e n D 1 1 SECTION 2 0 APPLICATIONS 24 APPLICATIONS da oot tua oes ELA E TR 2 1 Dalek E o 2 1 2 1 2 Diguid to G8 itio 2 1 2 12
5. 19 227 DIO ZENER 1N754A 6 8V 1 CRO2 19 227 DIO ZENER 1N754A 6 8V 1 CRO3 19 216 DIO 1 014 1 CRO4 19 216 DIO 1 914 EACH C001 10 122 CAP DT 47 MF 15V 20 R 1 C002 10 122 CAP DT 47 MF 15V 20 R 1 10 89 CAP 1 CDE WMF 1P1 1 C004 10 89 CAP MF 1 CDE WMF 1P1 1 5 10 53 CAP 5 200WVDC 5 MY 1 C006 10 104 CAP PF 30 CD10ED300J 03 1 C007 10 90 CAP MF 0047 CDE WMF 1D47 1 C008 10 90 CAP MF 0047 CDE WMF 1D47 1 C009 10 75 CAP CD 0015MF 1KV 10 R EACH C010 10 125 CAP MF 1 330 105 505 EACH C012 10 104 CAP PF 30 CD10ED300J 03 EACH J003 14 960 CONN CANNON ITT 9PIN M DEM 9PB 1 004 74 905 SKT CJ DIP 16 EACH PCBI 2416 63 1 PCB DPI NULL INDICATOR EACH P501 62 192 SEMICONDUCTOR Q23 010 115V EACH Q001 86 501 XSTR 2 3707 1 EACH ROO 67 221 RES CC 150K 50W5 00 RC20 1 ROO2 62 234 103 POT CE OHM 20 TURN MOUNT 1 67 425 RES MF 10K 10W1 00 RN55C EACH ROO4 67 430 RES MF 100K 10W1 00 RN55C 1 ROOS 67 428 RES MF5 11K 10W1 0099RN55C EACH 006 67 435 RES MF 1K 10W 1 00 RN55C EACH ROO7 67 425 RES MF 10W 1 00 RN55C 1 ROO8 67 425 RES MF 10W 1 00 RN55C EACH ROO9 67 423 RES MF 511 10W 1 00 RN55C 1 67 428 RES 5 11 10W 1 00 RN55C 1 RO11 67 425 RES 10K 10W 1 00 RN55C EACH RO12 67 42
6. be expected of it depend upon the performance characteristics of the individual transducer and the manner of its preparation for adjustment The permanency of the adjustment may be associated with 1 The magnitude of the zero shift of the pressure null indication with alternate overranging pressures and the direction of application of the last previous overranging pressure See Page 4 1 of the Model 2413 Manual for preparation of the transducer for adjustment 2 The direction in which the pinion is rotated for completion of the adjustment See Note page 6 3 Model 2413 Manual 3 The presence of an unrecognized pressure bias on the diaphragm ot the time of adjustment If the top section of the transducer contains a liquid at the time of adjustment removal of the pinion access plug and insertion of the adjusting screwdriver will create an abnormal pressure 10 1 TEST PROCEDURE bias on the diaphragm liquid pressure heads are different than for normal operations Allowance must be made for the magnitude of the head when making the adjustment either trial and error or by adjusting the external heads to match the internal ones Bias pressures from other sources may be present and unless they remain constant throughout the measurement process will affect the stability of the null pressure adjustment The accuracy to which the adjustment must be made will depend upon 1 The skill of the operator in neutralizing or otherwise account
7. by the adopted procedure i e from the liquid side The pressure is allowed to remain for a minute or so and then released In some manner the liquid system must be opened to atmosphere at a point level with the diaphragm An open tube manometer valve opened and the gas system also opened to atmosphere the liquid is adjusted to stand in the tube at the height of the diaphragm Under these conditions the pressure across the diaphragm is zero The electrical circuit with sensitivity set at maximum or whatever value has been chosen may then be adjusted for the meter to indicate zero AP As the manometer valve is closed the pumping action of the stem causes the liquid to rise slightly in the tube and ihe meter pointer to deflect The deflection is normal one which results from the disturbance of the liquid in the tube Before the measurement is begun the sensitivity is reduced by placing the shunt switch in the ON position The shunt switch reduces the gain of the circuit by a factor of approximately 1000 First the liquid pressure and then the gas pressure is raised in the manner described above As the gas pressure becomes approximately equal to that of the liquid it will be observed that the two pressures will rise simultaneously as the increase in gas pressure is continued At this time the diaphragm is being forced away from the lower cavity surface by the gas The displacement of the diaphragm increases the pressure in the liquid system A
8. pressure increases At elevated pressures the sensitivity is difficult to measure the observed value being at best only an estimate The experience i using the null transducer as a balance indicator when crossfloating two piston gages indicates that the sensitivity is reduced to 1 2 or 1 3 of its original value when operated near its maximum pressure The reduction is not serious however because as the pressure is increased the sensitivity becomes greater as a percentage of the total pressure APPENDIX A A 2 APPENDIX B DRAWINGS AND BILLS 2416 B 1 APPENDIX B THIS PAGE INTENTIONALLY LEFT BLANK APPENDIX B B 2 2416 BILL OF MATERIAL 2416 55 DIFFERENTIAL PRESSURE NULL INDICATOR CABLE ASSEMBLY W1 BOX TO CELL SEQ COMPONENT DESCRIPTION QTY UNIT OF NO ITEM NO MEASURE 01 14 817 CONN CONT PLUG SM7 20PGD EACH P002 14 817 CONN CONT PLUG SM7 2 PGD EACH 0001 14 818 CONN CONT AL HOOD SM7 20H 2 EACH 0002 75 105 SOLDER MULTICORE SN 60 22 1 001 EACH 0003 86 814 TBG PVC 105 BLK 066 ID x 016W 1316 FOOT 0004 86 803 POLYETHYLENE 1 4 OD x 04W 1 50 INCH 0005 94 233 WIRE BELDEN 8434 4 2416 3 APPENDIX BILL OF MATERIAL 2416 63 PRINTED CIRCUIT BOARD ASSEMBLY SEQ COMPONENT NO ITEM NO DESCRIPTION QTY U M CRO
9. quarter turn or less After reattaching the differential transducer to the system and pressurizing the opposite cavity to several hundred psi the experiment with the screw pump is repeated The difference in rotation of the screw crank in the two experiments represents the quantity of air remaining in the cell In these experiments the gage pointer must not be resting against a pin at zero pressure t is obvious that pressurizing the opposite cavity will prevent the flexible diaphragm from spoiling the experiment It is not difficult to keep the free air in the differential pressure transducer below 0 05 cc 3 2 BLEEDING LOWER CHAMBER IN A LIQUID TO LIQUID SYSTEM When charging the small cavity beneath the diaphragm a bias pressure is placed in the upper cavity to force the diaphragm against the lower cavity surface After the plug beneath the cell is loosened some liquid is forced into the lower fitting until the liquid appears around the plug threads This method is adequate in most instances A small bubble is trapped in the vertical section of the input port to the lower cavity but after pressurizing the liquid for a period and repeating the process the bubble is mostly displaced or dissolved For more thorough displacement of the air the cell should be inverted PREPARATION FOR USE 3 2 2413 SECTION 4 0 OPERATION 4 1 OPERATING INSTRUCTIONS In comparing the pressure of one system to that of another it must first be established tha
10. 08 TERM SUBMIN RED TEFLON EACH 9 35 514 TERM SUBMIN BROWN TEFLON EACH TP10 35 507 TERM SUBMIN WHITE TEFLON 1 TOO 86 440 XRMR DPC 120 35 SIGNAL 4 4VA 1 2001 2 705 AMPL IC UA747CN SIGNETICES EACH 2001 74 899 SKT CINCH DIP 14 N DIP EACH 2002 2 705 AMPL IC UA747CN SIGNETICS EACH 2002 74 899 SKT CINCH DIP 14 N DIP EACH 2003 35 486 IC ADOPO7DH 1 7003 74 941 SKT AUGUT 8058 1950 IPIN 23OD 1 2004 2 705 AMPL IC UA747CN SIGNETICS EACH 2004 74 899 SKT CINCH DIP 14 N DIP 1 2416 5 APPENDIX B BILL OF MATERIAL 2416 711 CONTROL BOX ASSEMBLY NULL INDICATOR SEQ COMPONENT UNIT OF NO ITEM NO DESCRIPTION a MEASURE 2416 61 STAND DIFF PRESSURE INDICATOR 1 000 EACH 0501 58 739 LAMP NEON 125 1 000 EACH F001 26 171 FUSE 3 82 250V 312 375 1 000 EACH 1001 14 814 CONN CONTINENTAL SM7 20SGD 1 000 EACH 001 46 23 JEWEL METER 73T SPECIAL SCALE 1 000 EACH WO01 2416 55 CABLE ASSY WI DPI TRDR CABLE 1 000 EACH 0001 2416 60 1 ENCLOSURE CPI CONTROL BOX 1 000 EACH 0002 2416 60 10 FR AND REAR PNL TPI NULL IND 1 000 EACH 0004 2416 62 ASSY WIRE HARN CNTR BOX DPI 1 000 EACH 0005 6 75 BEZEL KIT 1 000 EACH 0006 18 874 DIAL COUNTING 2 000 EACH 0007 2416 63 PRINTED CIRCUIT BOARD ASSEMBLY 1 000 EACH 0008 99236 225 NAMEPLATE 2 1 4 IN 1 000 EACH 0009 71 108 DRS 1 4
11. 2416 8 1 GENERAL INFORMATION THIS PAGE INTENTIONALLY LEFT BLANK GENERAL INFORMATION 8 2 2416 SECTION 9 0 FUNCTIONAL CIRCUIT DESCRIPTION 9 1 FUNCTIONAL CIRCUIT DESCRIPTION The excitation signal to the primary coils of the LVDT is generated by an oscillator made of Z2A and Z2B The output of the oscillator at TP7 is a 24 volt peak to peak sinusoid at a frequency of 5 1 KHz This signal is attenuated by R5 and R and buffered through Z1B The excitation signal TP6 to the primary coil has a magnitude of 4 volts P P The output of the LVDT is measured differentially and amplified by Z4B This error signal is then again amplified by ZAA The information present at the output of 74 is a sinusoid whose amplitude and phase or 1800 is a function of the position of the core in the LVDT This information is half wave rectified by Q1 is operated by the squarewave generator ZIA The result at TP5 is a positive or negative half wave sinusoid whose amplitude is a function of core displacement from the null position and whose polarity is a function of the direction of the core displacement The signal at TP5 is then integrated by R8 and C5 This DC level is then amplified through Z3 The gain of Z3 is controlled by the GAIN adjustment The ZERO adjustment provides a bias voltage added algebraically to the error signal via Z3 Resistor R29 and diodes and CR4 provide current and voltage limiting to the null meter R30 is a current li
12. 5 RES 10K 10W 1 00 RN55C EACH RO13 67 430 RES MF 100K 10W 1 00 RN55C 1 RO14 67 424 RES MF51 1K 10W 1 00 RN55C EACH RO15 67 432 RES 200 10W 1 00 RN55C 1 RO16 67 428 RES MF5 11K 10W 1 00 RN55C EACH RO17 67 435 RES MF IK 10W 1 00 RN55C EACH RO18 67 432 RES 200K 10W 1 00 RN55C EACH RO19 67 425 RES 10K 10W 1 00 RN55C 1 RO20 67 424 RES MF51 1K 10W 1 00 RN55C 1 APPENDIX B B 4 2416 RO22 67 432 RES 200K 10W 1 00 RN55C EACH RO23 67 425 RES 10W 1 00 RN55C 1 EACH RO24 67 435 RES MF IK 10W 1 00 RN55C 1 RO25 67 434 RES 75K 10W 1 00 RN55C 1 RO27 67 434 RES 75K 10W 1 00 RN55C EACH RO29 67 435 RES MF IK 10W 1 00 RN55C 1 RO3O 67 436 RES MF 2K 10W 1 00 RN55C EACH RO31 67 435 RES MF IK 10W 1 00 RN55C EACH RO32 67 432 RES MF 200K 10W 1 00 RN55C EACH RO33 67 469 RES MF 100 10W 1 00 RN55C 1 RO35 67 341 RES WW 1K 3 00W 1 00 RS2B 1 1 35 511 TERM SUBMIN BLUE TEFLON EACH 2 25 509 TERM SUBMIN BLACK TEFLON EACH 35 507 TERM SUBMIN WHITE TEFLON 1 35 515 TERM SUBMIN GRAY TEFLON EACH 5 35 515 TERM SUBMIN GRAY TEFLON EACH TPO6 35 512 TERM SUBMIN ORANGE TEFLON 1 7 35 512 TERM SUBMIN ORANGE TEFLON EACH TPO8 35 5
13. 59 119 19 Transformer Block 1 2413 1 1 20 Lower Body 1 2413 1 7 21 Socket Cap Screw 12 70 230 3 8 x 1 1 2 22 Round Head Screw 2 70 120 05 06 4 x 1 2 23 Lead Thru Assembly 3 2413 023 24 Coupling Body 2 2103 1 25 Tube Nut 2 2113 1 1 26 Receptacle 1 14 814 27 Round Head Screw 1 70 110 05 06 2 x 3 16 N Shown Screwdriver 1 71 490 N Shown Transducer Support Assy 1 2413 3 PARTS LIST 7 4 2413 SECTION 8 0 GENERAL INFORMATION 8 1 INTRODUCTION This instrument employs contemporary time proved analog techniques The components were chosen for their long term stability and reliability Numerous test points exist on the circuit board that facilitate trouble shooting when necessary The operational amplifiers are plug in which allows for easy installation The 15 volt DC system is powered by a modular power supply which is in turn fully isolated from line voltages through a dual primary input isolation transformer The input line voltage 120 Vac or 230 Vac at 50 Hz or 60 Hz is selectable by means of a small circuit board located internal to the power cord receptacle Removal of the power cord allows access to the fuse and circuit board compartment The front panel controls include a power switch and indicator a 3 5 inch null meter a ten turn ZERO potentiometer with calibrated dial a ten turn GAIN potentiometer with calibrated dial and a SHUNT switch that allows discrete high and low gain selection
14. DIFFERENTIAL PRESSURE NULL INDICATOR MODEL 2413 2416 USER S MANUAL RUSKA INSTRUMENT CORPORATION 10311 WESTPARK DRIVE HOUSTON TX 77042 713 975 0547 FAX 713 975 6338 e mail ruska ruska com Release 2413 1001 Revision D Date June 27 2002 WARRANTY Ruska Instrument Corporation warrants its products to conform to or exceed the specifications as set forth in its catalos in use at the time of sale and reserves the right at its own discretion without notice and without making similar changes in articles previously manufactured to make changes in materials designs finish or specifications Ruska Instrument Corporation warrants products of its own factory against defects of material or workmanship for a period of one year from date of shipment Liability of Ruska Instrument Corporation under this warranty shall be limited to replacing free of charge FOB Houston Texas any such parts proving defective within the period of this warranty but will not be responsible for transportation charges or consequential damages This warranty is not made for products manufactured by others which are illustrated and described in Ruska catalogs or incorporated in Ruska products in essentially the same form as supplied by the original manufacturer However Ruska Instrument Corporation agrees to use its best efforts to have original suppliers make good their warranties li INTRODUCTION COPYRIGHT NOTICE Copyright 1990 1992 by Ruska In
15. PARENT SENSITIVITY Although the differential pressure indicator is regarded as a null indicating instrument the degree to which a true null may be achieved depends upon the readability of the error signal displayed on the meter In order to obtain a readable error signal the diaphragm must move The sensitivity of the instrument is expressed as the change in pressure divided by the corresponding change in meter reading the change in meter reading being a function of the motion or displacement of the diaphragm The sensitivity must be determined in such a way that the tension in the diaphragm resulting from the applied pressure is the only restoring force which re establishes equilibrium When one side of the diaphragm is opened to atmosphere and a small increment of pressure is applied to the other side the diaphragm will move under the influence of the applied pressure The motion will continue until the forces tending to move the diaphragm are equally opposed by the forces of tension in the diaphragm tending to resist the motion The sensitivity is then equal to AP divided by the change in meter reading When one side of the diaphragm is connected to a single ended system containing a gas under pressure the circumstances are different The forces of an applied pressure increment tend to move the diaphragm as before but the forces resisting the motion are greater than before As the diaphragm moves the volume of the single ended system is r
16. When the two gages are at pressure and approximately balanced the valve is opened and the electrical zero adjusted The valve is then closed and the balancing operation continued while observing the residual pressure difference on the meter As the pressures become more nearly equal the valve is opened to verify the correct zero adjustment and then closed and opened alternately until no difference in meter readings is observed when the valve is either open or closed The resolution of the entire system is quickly determined by placing a small weight on one gage and observing the effect on the meter When using the transducer for this purpose calibration of the null shift with working pressure is unnecessary APPLICATIONS 2 2 2413 SECTION 3 0 PREPARATION FOR USE 3 1 PREPARATION FOR USE Normally when a transducer is shipped from the factory it has been calibrated with nitrogen and is dry in both cavities Before installation a quick performance tests may be made by first connecting the box to the cell with power on adjusting the sensitivity to maximum and the meter to zero By pressing against the end of the open fittings with the finger the meter will be seen to deflect The effect will be less when pressing on the upper fitting since the upper cavity has a volume some fifty times greater than the lower cavity At maximum sensitivity it should be relatively easy to deflect the meter from zero to full scale when pressing on the lower fi
17. d has been used in the transformer changer pour out the remaining liquid and flush the chamber with a mild solvent Do not remove any part of the electrical connectors and be very careful not to disturb any of the internal wires 6 With the cell inverted in the vise carefully remove the bottom body closure Part 20 Do not touch the cavity surface of Part 20 A metallic seal is effective only when the sealing surfaces are well polished and free of scratches The sealing surfaces of the diaphragm and cavity have been polished in a circular direction and the resulting pattern must be maintained to accomplish the seal When cleaning the surfaces a soft paper wiper Kleenex saturated with a solvent may be used in a circular motion Such a motion will avoid producing radial hairline scratches and an invitation for leaks The cavity surfaces should be kept upward and covered when placed on the table The diaphragm usually remains in the middle body 17 Examine the diaphragm before removing it for impressions or perforations from solid particles The direction of the impression will indicate from which side the perforation was made Usually the particle that caused the perforation may be located and identified Carefully lift the diaphragm out and examine the contents of the other cavity If particles are present some effort should be made to identify them for the purpose of eliminating their source Metallic particles in particular have a way
18. educed and its pressure increased The AP that was applied to the diaphragm is automatically diminished and the instrument sensitivity appears to be less than before An example of the extreme case is one in which the single ended system is completely filled with a non compressible liquid As the pressure is increased on the opposite side of the diaphragm the liquid will not permit the diaphragm to move In this instance the sensitivity will appear to be very poor but the actual sensitivity is no different than when measured under ideal conditions 5 2 CALIBRATION The calibration procedure consists of determining he pressure coefficient of the transducer the maximum sensitivity and the zero shift that accompanies alternate over ranging pressures on the diaphragm The pressure coefficient is usually small on an average being less than 10 psi When the transducer is used in a bi fluid system for the calibration of elastic pressure measuring devices the error of the transducer can often be disregarded When used in an apparatus for basic PVT studies the coefficient is significant and its expression is of more value if reported in units of diaphragm displacement per unit of pressure level rather than as a change in pressure differential per unit of pressure level For very small samples the displacement of the diaphragm can result in an intolerable change in the sample volume and the error will not be corrected by an adjustment of the pr
19. ement and must not be overlooked 5 3 DETECTING LEAKS The differential pressure unit may be used to indicate a change in pressure of one system with respect to that of another The change may result from a leak or from a change in temperature When the instrument is used for detecting leaks in a system sufficient time must be allowed to eliminate temperature effects Also a leak in a liquid system will have a different rate indication than a leak of the same magnitude in a gas system Some caution must be exercised when interpreting the results of this type of test PERFORMANCE OBSERVATIONS 5 2 2413 SECTION 6 0 MAINTENANCE 6 1 SERVICING THE INSTRUMENT Failure of the instrument may result from a malfunction of the following components n Duo Diaphragm Differential Transformer Electrical Feed Throughs Connecting Cable Electronic Circuit 6 2 DIAPHRAGM In most instances failure of the transducer has been traced to perforations in the diaphragm caused by particle contamination of the fluids When the cell is over ranged from one side the diaphragm is driven to and pressed firmly against the surface of the opposite cavity If a particle of sufficient size is present in that cavity the impression of the particle against the diaphragm will cause a perforation The diaphragm must of course be replaced A perforated diaphragm may be detected from one or more of the following symptoms A Liquid to Gas System 1 2 Otherw
20. essure in 2413 5 1 PERFORMANCE OBSERVATIONS the amount indicated a pressure correction curve calibrating procedure in which ihe diaphragm presumably can be restored to its isostatic position by a physical adjustment of the electrical sensing indicating circuit has been adopted The procedure involves simultaneous pressurization of both sections of the transducer from a common source and measuring the correction required to maintain a null indication throughout a range of pressures The correction is applied as a change in the ten turn zero adjusting potentiometer the shaft of which is equipped with a turn counting graduated dial In practice the dial knob is set near one end of its range and the transformer of the pressure cell adjusted to indicate an approximate null when the diaphragm is exposed to atmospheric pressure on each side At each pressure level of operation the dial is changed by an amount obtained from the calibration curve The curve is plotted as the change in dial units as a function of operating pressure Usually it is necessary to decrease the dial registration as the pressure is increased The advantage of maintaining a more uniform volume of the sample by accepting the method of calibration just described outweighs the convenience of correcting the data by a computer adjustment of the errors in pressure resulting from the strain in the transducer Manual adjustment of the potentiometer becomes a part of each measur
21. ft in the zero position of the diaphragm as a result of alternate overranging pressures is obtained by pressurizing one side of the diaphragm to 2000 psi or so for a few minutes The pressure is then released and the transducer allowed time to recover After setting the meter to null the opposite side of the diaphragm is pressurized by the same amount Upon release of the latter pressure and recovery of the transducer a small U tube manometer is connected to the appropriate side and the pressure required to restore the original null is measured This figure is characteristic of the diaphragm and in some instances is small enough to allow indiscriminate overranges The sensitivity at maximum gain is obtained by measuring the differential pressure required to sweep the meter pointer across the scale several times in a stepping fashion 1 APPENDIX The pressure is established with the manometer and is measured with respect to the atmosphere After the meter pointer is set to the appropriate end of the scale pressure is applied until the pointer sweeps full scale to the opposite end While the pressure is maintained the pointer is returned to the original end of the scale and the process continued until a substantial head has been established in the manometer The total pressure divided by the total number of units through which the pointer has passed is the sensitivity in pressure units per meter unit The sensitivity decreases as the working
22. he cell is accidentally over ranged from the opposite side there is no harm except for a temporary loss of the original null setting The cell must then be over ranged from the original side to re establish the true null Values shown under this heading are nominal at time of this publication and not to be considered as binding specifications They are subject to change with improvements in design and technoclo DESCRIPTION amp SPECIFICATIONS 1 2 2413 Approximate Range of AP 2 psi Volumes of Cavities Upper 29 5 cc Lower 0 6 cc Effective Diameter of Diaphragm 1 9 inches Thickness of Diaphragm 0 001 inch Types of Fittings For 2413 Series Ruska 60 cone with 3 8 24 straight thread male cone fitting female cone in body of cell Fittings and nut for 3 16 stainless steel 60 flared tubing For 2417 Series NBS threaded cone fittings 2413 1 3 DESCRIPTION amp SPECIFICATIONS THIS PAGE INTENTIONALLY LEFT BLANK DESCRIPTION amp SPECIFICATIONS 1 4 2413 SECTION 2 0 APPLICATIONS 2 1 APPLICATIONS The Model 2416 may be employed as a null detector indicator in the following manner 2 1 1 GAS TO GAS The instrument may be used with dry air nitrogen carbon dioxide some hydrocarbons and the noble gases but not with gases containing free hydrogen or oxygen Although oxygen will not directly attach the materials of the lower cavity there is the danger that an accidentally perforated diaph
23. he top of the chamber and be expelled through the vent port The presence of a bubble in the top of the cell cavity does not affect the measurement significantly but it does affect the response It is therefore convenient to work the air out of the cavity as much as is practical The cavity may also be charged by first evacuating and then admitting the liquid to the evacuated chamber Usually some small bubbles still remain because of the difficulty in reducing the internal pressure sufficiently through the small bore tubing The presence of remaining air in the cavity may be measured if the liquid pressure generator is a screw type displacement pump and the system contains a Bourdon tube reference gage It is first necessary to measure the air that exists in the portion of the liquid system other than the transducer To make this measurement it is necessary to isolate the liquid system from the cell and the dead weight gage if one is used If there is no valve on the line to the cell the line must be temporarily disconnected and stopped 2413 3 1 PREPARATION FOR USE off The valve to the liquid supply reservoir is opened and the plunger advanced somewhat to remove the backlash in the pump spindle nut With the reservoir valve closed the screw crank is slowly rotated until the Bourdon gage pointer is observed to move a perceptible amount The quantity of motion of the screw is noted The motion of the crank should be small something like one
24. he transformer is free Remove the transformer and flush the cell again as in Operation 2 Do not disturb the core on the diaphragm stem Insert the new transformer The wires may be somewhat loner than the original ones but it makes no difference it is not necessary to shorten them Solder the wires to the terminals following the color code on the diagram See Operation 5 Try to prevent oxides and excess flux from dropping into the cavity If necessary flush the cavity when the soldering is complete Replace the detent Make the primary and secondary resistance tests Plug the box in and allow the circuit to warm up a Set the gin to maximum b Set zero control to 800 or so c Rotate the pinion 16 until the meter reads zero Wash the upper body and bolts and replace the O ring in the cap if it shows evidence of extrusion Do not use a hard metal object to remove the O ring use a toothpick or wood match Trichlorethylene has been declaried toxic by Occupational Safety and health Administration use only with proper precautions See note regarding trichloroethylene 2413 6 5 MAINTENANCE 15 With the cell in the vise assemble the upper body and torque the bolts down evenly to 35 foot pounds 16 Connect the box to the cell and test the performance by pressing the finger against the end of the lower fitting At maximum sensitivity it should be possible to pin the meter from zero by pushing against the fit
25. i maximum over range pressure both series 1 2 SPECIFICATIONS Inaccuracy Inaccuracy is defined as the error in the null indication It is expressed as the ratio of AP actually existing when the meter indicates a null to the total cell pressure in parts per million or as constant AP whichever is greater PPM AP PSI Error with calibration corrections 5 0 01 Error without calibration corrections 20 0 1 Sensitivity The sensitivity is continuously variable from 2 10 psi AP per meter division to 0 01 psi AP per meter division The maximum value may exceed 2 10 psi div because of variations in diaphragm characteristics and circuit parameters Operating Pressure 15 000 psi liquid or gas for 2413 Series cells 40 000 psi for 2417 Series cells See pressure media for limitations Static Test Pressure 22 000 psi for five minutes with nitrogen The ungasketed metal seals act as relief valves when pressures exceed 22 000 psi The bolts yield to the increased lead and permit the excess pressure to escape All attempts at destructive testing of these units have failed 50 000 psi for 2417 Series cells 2413 1 1 DESCRIPTION amp SPECIFICATIONS Over Range Pressure 15 000 psi AP either side of diaphragm for both 2413 and 2417 Construction Material Basic material of the transducer is one of the 400 Series Stainless Steels Pressure Media Lower Chamber of pressure cell Dry air nitrogen mercury or any fluid inert to 400
26. ich the transformer windings open at high pressure will exhibit the above symptoms temporarily above some value of pressure The meter pointer will be seen to dive to the pin as the pressure is increased When the meter becomes uncontrollable at high pressure the cable connector may be removed from the cell or the box and the above tests made while the cell is under pressure Occasionally after a prolonged period of over ranging pressure of the diaphragm in the direction of a liquid medium it is possible for the diaphragm to stick to the cavity surface With the diaphragm in this position the cell displays the same symptoms as those of a defective transformer The resistance tests will indicate which of the conditions exist 6 4 REPLACEMENT OF TRANSFORMER Refer to 2413 Parts List and Sectional Diagram Figure 7 1 and 7 2 Replacement of the transformer should be performed on a clean bench 1 Wash the cell down thoroughly on the outside with a volatile solvent and dry with clean air 2 Grasp the flats of the cell firmly in a vise the jaws of which are covered by brass or aluminum plates Pieces of paper against the flats will help prevent the polished surfaces from becoming scratched The cell should be grasped beneath the cable receptacle 3 Remove the upper body Part 2413 1 1 and lay it aside inverted on a clean piece of paper MAINTENANCE 6 4 2413 4 Remove the cell from the vise and pour the liquid from the cavity Whi
27. ing for the abnormal pressure bias on the diaphragm as described in 3 above 2 The number of potentiometer dial units that span the change in null indication from zero to full working pressure This information is obtained from the calibration report The curve representing the change in potentiometer dial counts versus operating pressure level indicates the total number of counts that must be available to the operator for completion of his process The zero adjustment potentiometer must be offset at the initial adjustment to accommodate this range of operation TEST PROCEDURE 10 2 2416 APPENDIX EXPLANATION OF TEST REPORT When the Ruska Differential Pressure Null Transducer is operated at an elevated pressure the body is in a state of temporary strain Even though the pressure on each side of the diaphragm may be equal as they are when the two cavities are connected together the output display meter indicates that a difference in pressure does exist This erroneous indication is caused by a displacement of the transformer with respect to the diaphragm and is a result of the strain in the body Since the position of the diaphragm is of great interest when making PVT experiments the value of the change must be determined by calibration The reported result of the calibration is the apparent change in the original setting of the zero adjusting potentiometer as a function of the pressure within the transducer In practice after the neces
28. ise unexplained presence of gas in the liquid portion of the cell Continuous increase in liquid pressure when the cell is over ranged from the gas side Erratic behavior of the cell caused by traces of liquid in the gas cavity A wet bore in the fitting to the gas cavity an indication that the liquid has migrated as far as the fitting B Liquid to Liquid System Periodic physical tests on one of the liquids to detect the presence of contamination by the other liquid i e a fluorescent residue from an evaporated sample of Freon in a Freon to oil system 6 2 1 REPLACEMENT OF DIAPHRAGM IN MODEL 2413 TRANSDUCER Refer to 2413 Parts List and Sectional Diagram Replacement of the diaphragm should be carried out on a clean bench 1 Remove the circular cast base and unscrew the three supporting studs from the cell body The studs may be grasped in a vise the jaws of which are covered with brass or aluminum plates 2 Wash the cell down thoroughly on the outside with a volatile solvent and dry with clean air 3 Grasp the flats of the cell firmly in a vise the jaws of which are protected Pieces of paper against the flats will help prevent the polished surfaces from becoming scratched The cell should be grasped beneath the cable receptacle 2413 6 1 MAINTENANCE 4 Remove the upper body Part 2413 1 8 Symbol 1 of Figure 7 2 and lay it aside inverted on a clean piece of paper 5 Remove the cell from the vise If a liqui
29. le holding the cell semi inverted about 45 with bottom up over a rather large container direct a stream of solvent Freon TF or TRICHLOR into the cavity and particularly around the feed through terminals 2 or 3 ounce plastic ear syringe is suitable for this purpose The reason for inverting the cell while flushing is to prevent any solid contaminates that may have come to rest in the transformer chambers from being washed into the diaphragm cavity Mark the sectional diagram with the proper wire colors for the transformer leads Carefully lift the wires off the feed through terminals using a 25 watt pencil type soldering iron As each wire is lifted measure the resistance of the feed through terminal to ground The resistance should be greater than 1 megohm The terminals should not be overheated with the iron since the gasket will be damaged If there is any reason to believe that the resistance measurements in the previous section could be confused by an abnormally low resistance to ground by way of the feed through terminals the resistance measurements should be repeated at the transformer leads before the transformer is completely removed 6 Remove the wires from ground Remove part symbol 5 detent 8 Turn the pinion symbol 16 counterclockwise while preventing transformer from 12 13 14 rotating with the other hand Do not bend the wires where they are attached to the transformer Continue to turn until t
30. lthough the two pressures are approximately equal a signal will not appear on the meter until the gas pressure is within 2 psi of the liquid since this figure is the limiting value of the indicated differential pressure Some liquid 2413 4 1 OPERATION must withdrawn from the differential pressure cell allowing the diaphragm to move toward the center of the cavity whereupon the meter signal will approach the zero If a dead weight gage is connected in the system the pressure in the liquid may build up high enough to float the weights With a slight excess of gas pressure the diaphragm will then move freely across the cavity the weights will be seen to rise rapidly After the sensitivity is increased by placing the shunt switch in the OFF position the two pressures may be brought to a satisfactory balance The increase in pressure of the two fluids is accompanied by an increase in temperature As the fluids give up their excess heat to the apparatus each suffers a reduction in energy While the piston gage is floating however it acts as a regulator and holds the pressure of the liquid approximately constant The shrinkage of the liquid from its loss in heat is reflected as an increase in the normal sink rate of the piston The gas being confined to a single ended system suffers a loss in pressure as it gives up its excess heat The net effect is an unstable condition in which the indicator will signal a continuous reduction in the gas p
31. miter to the recorder output jack Resistors R25 R26 R27 and R28 determine the ZERO control sensitivity and span 2416 9 1 FUNCTIONAL CIRCUIT DESCRIPTION THIS PAGE INTENTIONALLY LEFT BLANK FUNCTIONAL CIRCUIT DESCRIPTION 9 2 2416 SECTION 10 0 TEST PROCEDURE Reference to Drawing Nos 2416 60 200 and 2416 63 is recommended A DC voltmeter with 001 volt resolution is sufficient for the single required potentiometric adjustment For trouble shooting an oscilloscope will be required All measurements are made with respect to TEST POINT 2 TP2 1 Setup Procedure A 2416 Set Gain control to maximum full clockwise Set ZERO control to mid point Set SHUNT to ON Connect the transducer Turn power ON Observe the voltage at TP4 Adjust P1 to yield minimum DC volts Adjust the transformer in the transducer until the meter indicates null It must be noted here that for oil filled transducers insertion of the screwdriver will affect null position The oil displaced by the screwdriver will create a pressure head The head must be considered The head pressure will become more important as the test procedure progresses to the stages of higher amplification Set SHUNT to OFF This condition provides maximum amplification of null sensing The final adjustment of the transducer transformer prepares the instrument for use The accuracy with which the adjustment is made and the permanency that may
32. n may be balanced against the oil dead weight gage system to pressures as high as 40 000 psi Such systems are somewhat more economical than equivalent liquid to gas systems since the pressurizing apparatus is less expensive With the possible exception of use with the highly volatile fluorocarbons it is not recommended that a cell be purchased for alternate use in liquid to liquid and liquid to gas service In order for the cell to perform properly the diaphragm cavity must either completely filled with liquid or it must be completely dry A trace of liquid in the otherwise dry cavity will upset the performance as quickly as will an air bubble in the liquid cavity In each instance the surface tension effects are greater than the AP error signal being observed 2413 2 1 APPLICATIONS Whenever a liquid is used in either side of the transducer an open tube manometer must be connected in such a way that the pressure across the diaphragm may be adjusted to zero and that the meter may also be adjusted to indicate zero In a liquid to liquid system two manometers must be used one in each of the liquid systems Manometers suitable for this purpose are available A special application of the differential pressure null indicator is one i which the unit is used when cross floating two dead weight gages by pass valve arrangement is provided for the purpose of directly connecting the two gags while making preliminary balancing adjustments
33. of appearing mysteriously in places where it is certain that none previously existed lt is suspected for instance that the action of valve stems within their bodies are the source of some particle contaminants Do not remove the core from the stem 7 Immerse all parts in trichloroethylene or Freon TF and allow to soak several minutes Direct a stream of the solvent from a plastic ear syringe directly at the transformer assembly The transformer is vented and some solvent may carefully be flushed into the vents with the syringe Do not touch the wires as they are fragile Direct a stream through the hole from the lower side of the central body toward the corrugated springs 11 and 12 8 Referring to the diaphragm measure the distance from the transformer core to the top surface of the diaphragm or to the top of the attached button Transfer the core to a position on the stem of a new diaphragm equal to that on the stem of the old diaphragm It is not difficult to duplicate the position to within 01 or 02 inch at which point the core will be within the range of adjustment of the transformer The split core sleeve is held in position by friction and is not difficult to remove with the fingers If the friction appears to be insufficient the sleeve may be squeezed slightly to reduce the inside diameter before installation on the new stem Statements referring to the effects of liquids are not applicable to the Model 2413 751 which is
34. or 300 Series Stainless Steels Upper Chamber Dry air nitrogen or any fluid inert to 400 or 300 Series Steels low carbon iron brass copper PVC cadmium plated steel or soft solder Electrolytes may not be used ion the upper chamber It is not recommended to use fluids in either cavity containing free hydrogen The use of such fluids is hazardous because of possible hydrogen embrittlement of the cell body Consult the manufacturer for cells of special materials Temperature Range 400 to 1600 F Construction Details and Parameters Change in Null with Working Pressure See Specifications The stress from the applied pressure produces a displacement of the core within the transformer even though the pressure across the diaphragm may be zero The displacement results in a shift of the apparent null with the true null and is approximately a linear function of the pressure A calibration curve is supplied with each instrument to indicate the magnitude of the null shift Change in Null with Over Range Pressure 0 05 psi The null change with over range pressure arises from dimensional variations within the cell body The value shown represents the maximum expected change when the cell is over ranged from alternate sides of the diaphragm In practice a procedure is used that permits intentional over ranging from only one side After several such applications of over range pressure from the same side null indication becomes stable If t
35. ory a transformer occasionally breaks down under the severe conditions within the cell NOTE For permanency of adjustment the final rotation of the pinion must be in a clockwise direction When the pinion is rotated clockwise the backlash is removed from the mounting threads in a direction as to oppose the compression of the springs At least 1 2 revolution of the pinion is necessary to be assured the backlash 15 completely eliminated 2413 6 3 MAINTENANCE 6 3 1 FAILURE DIAGNOSES Some transformers have been known to fail at high pressure and to resume operation at a lower pressure Failure is usually traced to an opening in one of the windings A symptom remedy table is given which describes tests to be made for defective transformers Symptom Reason for Failure Test amp Correction Procedure Transducer cell insensitive to Open Primary Measure DC resistance change in pressure between pin socket A Ground Meter can be zeroed with to If resistance greater than zero adj 1000 ohms primary is open Normal primary resistance 310 ohms Replace transformer Meter pointer hard against Open Secondary Measure resistance pin Cannot be brought to between pin socket C Ground zero with zero adj Cell to D and C to F Normal insensitive to pressure resistance of one secondary winding is 105 ohms A high resistance of either winding indicates coil is open Replace transformer The occasion on wh
36. ragm will permit the oxygen to enter the upper cavity The organic materials in the upper cavity propose a hazard in the presence of compressed oxygen In all instances where a gas is used no liquid vapors should be permitted to enter the diaphragm cavity as the surface tension effects of condensed vapors will surely spoil the performance of the diaphragm 2 1 2 LIQUID TO GAS As a rule the instrument is used to separate a liquid pressure medium from a gas The ungasketed diaphragm seals and the small volume of the lower diaphragm cavity are features included for the requirements of PVT determinations Transducers with special electrical connections for submerging in a liquid temperature bath are available for PVT experiments When used with a dead weight gage the transducer affords a means of calibrating elastic sensors with inert gases The sensors such as transducers and bourdon tube gages may then be used in systems containing oxygen 2 1 3 LIQUID TO LIQUID The Differential Pressure Transducer may be employed as a null detector between two liquid systems For instance when calibrating elastic sensors prepared for oxygen service it is sometimes more convenient to use a liquid pressure medium than to use a gas The liquid medium of course must be chemically inactive in the presence of oxygen in all concentrations Mixtures of the volatile fluorocarbon solvents are frequently used for this purpose The system containing the fluorocarbo
37. ressure as through the system were leaking For rather large changes in the pressure level the balance indication will approach a high state of excitement for the first minute or so Complete stabilization will require a period of up to one hour but for calibration purposes manual control of the gas will be possible after only a few minutes In reducing the pressure the procedure is reversed The gas pressure is first reduced and then followed by the liquid pressure At the conclusion of the measurement some time must be allowed for the transducer to recover before the zero pressure conditions are verified Particularly if the last reduction in pressure is of one or more thousand psi the recovery period may be as much as 5 to 10 minutes A considerable quantity of heat is exchanged in the reduction process The procedure for operating a liquid to liquid system is much the same as described above except that a second manometer is required in the second liquid portion of the system When adjusting the differential pressure unit at the beginning of the test both manometers must be opened to atmosphere and each liquid adjusted to the height of the diaphragm It must be remembered that the density of the one liquid is often different from that of the other the total head correction must consider the two densities with their interface at the diaphragm OPERATION 4 2 2413 SECTION 5 0 PERFORMANCE OBSERVATIONS 5 1 ACTUAL SENSITIVITY VERSUS AP
38. sary proof pressure and leak tests have bee completed a common gas pressure is applied to both sides of the diaphragm As the pressure is increased in uniform increments the output meter is restored to its null position by adjustment of the zero potentiometer The value of the counter type dial on the zero adjusting knob is recorded for each increment The difference in these values and that of the original zero is plotted against their corresponding internal pressures and a smooth curve is fitted to the set of points Unless otherwise stated on the report the curve represents values observed at the maximum gain of the indicating circuit Negative values for the abscissae imply that the observed readings of the dial are less than that of the original zero Curves are constructed for both increasing and decreasing internal pressures In use it is necessary to determine from the curve the change in dial setting for the pressure at which the cell has become stable subtract this number from that observed when the cell was exposed to the atmosphere and set the dial to the new figure When the two mediae are balanced the diaphragm will be in its original position and the pressure across it will be zero The gain of the electronic circuit is such that on an average a displacement of the diaphragm of 0 75 microinch is equivalent to one unit indicating meter This information is of use in making an error analysis of the measurement process The shi
39. strument Corporation All rights reserved This document may not be reproduced in part or in while without the express written consent of Ruska Instrument Corporation DISCLAIMER No representations or warranties are made with respect to the contents of this user s manual Further Ruska Instrument Corporation reserves the right to revise this manual and to make changes from time to time in the content hereof without obligation to notify any person of such revision TRADEMARK NOTICE RUSKA Trademarks or tradenames are subject to state and federal laws concerning their unauthorized use or other infringements The fact that the product marks or names in this manual do not bear a trademark symbol DOES NOT mean that the product name or mark is not registered as a trademark or tradename Any queries concerning the ownership or existence of any trademarks or tradenames mentioned in this manual should be independently confirmed with the manufacturer or distributor of the product is a trademark of Ruska Instrument Corporation iii INTRODUCTION REVISION NOTICE RELEASE REV DATE OF DESCRIPTION NUMBER RELEASE 2413 1000 Unknown Original release 2413 1000 09 30 90 Updated to new Manual Format 2413 1000 05 12 92 Text changes ECO 18024 2413 1D01 D 06 27 02 Combined 2413 amp 2416 manuals to form 2413 1001 Revision D Manual See DC RO 23407 INTRODUCTION REVISION HISTORY
40. t the comparator or indicating device is adjusted correctly The adjustment must assure the operator that all hydraulic and pneumatic heads have been accounted With the transducer connected between two systems and prepared for operation the power is turned on and the circuit alloved to warm up for ten minutes A sequence of operations must be adopted in which one of the systems is always at a higher pressure than the other during the period of change from one pressure to another If there is a choice it is of some advantage in a liquid to gas system to maintain the higher pressure in the liquid system during the period of change This procedure is not difficult to execute for both increasing and decreasing changes in pressures If it is intended to raise both system pressures from one level to a higher one the liquid pressure is raised first to a value somewhat below the final one The diaphragm of the differential pressure cell is driven to the lower cavity surface where it supports the excess liquid pressure The operator is then free to concentrate on raising the gas pressure to but not in excess of the liquid pressure As the final pressure is approached it is usually possible to raise both systems simultaneously while keeping them sufficiently balanced for the meter pointer to remain on scale Before starting measurement on a liquid to gas system the differential pressure transducer is intentionally over ranged in the direction proposed
41. ting this is a very rough quantitative test MAINTENANCE 6 6 2413 SECTION 7 0 PARTS LIST When ordering parts refer to Figures 7 1 and 7 2 on pages 7 2 and 7 3 to determine reference symbol Ruska stock number corresponding to the reference symbol will be found listed on page 7 4 Serial number of the instrument and Ruska stock numbers of parts required must accompany all orders for replacement When returning the instrument to the factory for servicing the indicator control circuit must always accompany the transducer 2413 7 1 PARTS LIST FIGURE 7 1 2413 711 DIFFERENTIAL PRESSURE NULL INDICATOR PARTS LIST 7 2 2413 FIGURE 7 2 2413 711 DIFFERENTIAL PRESSURE NULL INDICATOR 2413 7 3 PARTS LIST PARTS LIST DIFFERENTIAL PRESSURE CELL SYMBOL DESCRIPTION QTY RUSKA STOCK NO 1 1 2413 1 8 2 Socket Cap Screw 12 70 229 3 8 x 1 1 4 3 Socket Cap Screw 3 70 122 4 x 3 4 4 Terminal Block 1 2413 1 16 5 Detent 1 2413 1 4 6 Round Head Screw 1 71 132 4 x 5 16 7 Differential Transformer Assy 1 2413 020 0 8 Adjustment Gear 1 2413 1 3 9 Transformer Armature 1 86 396 10 Washer 1 2413 1 14 11 Wave Washer 1 2413 1 11 12 Washer 1 2413 1 13 13 Diaphragm Assembly 1 2413 012 14 Tube Plug 2 2118 1 1 15 O Ring 1 54 900 035 16 Adjustment Pinion 1 2413 1 5 17 Middle Body 1 2413 1 6 18 2
42. tting Because of the small volume it is of some advantage to connect the lower cavity to the gas portion in a liquid to gas system When so connected less work will be done in raising the gas pressure All fluids should be filtered before their introduction into the pressure system A small hard particle such as metal chip in the diaphragm cavity will perforate the diaphragm when the cell is over ranged Every effort should be made to keep contaminating particles out of the transducer In charging the upper cavity with a liquid it is important to displace most of the air with the liquid There are many traps in the cavity which may retain small air bubbles If these bubbles remain in contact with the diaphragm or stem which carries the transformer core the performance will be erratic The fact that the air bubbles dissolve in the liquid when the pressure is increased may be used to an advantage With the vent plug removed the liquid is pumped into the upper chamber until it appears at the vent port The plug is replaced and the pumping continued until he pressure in the liquid system reaches 150 atmospheres or so At this pressure the entrapped bubbles dissolve in the liquid forming a concentrated solution in the vicinity of the trap Some time should be allowed for the solution to diffuse so that when the pressure is released the bubbles will not reappear in the same trap The bubbles must reappear at some new point where they may rise to t
43. uce the tendency for the undesirable motion Place the cell bottom up in the vise and proceed to tighten the bolts systematic procedure must be followed to assure uniform results in the tightening process Pull the four initial bolts up hand tight with a standard hex key working across and then around the bolt circle Pull up the remaining bolts in the same manner When all bolts are hand tight start tightening with a torque wrench in 5 foot pound increments until the circle is complete at 35 foot pounds Make one additional cycle at 35 foot pounds 10 Before replacing the top body attach the cable to the cell turn the power on and allow circuit to warm up a few minutes Set the zero control near the high end of the range about 800 and gain to maximum Shunt switch in OFF position Adjust the position of the transformer by means of the pinion 16 until the meter indicates approximately zero 11 Replace the cap and torque the bolts down to 35 foot pound in the same manner as described in 9 above Since the cap 1 is sealed with an O ring the tightening procedure is not as critical as then when securing the lower cap 20 6 3 REPLACEMENT OF DIFFERENTIAL TRANSFORMER IN THE 2413 D P NULL INDICATOR A serious effort has been directed toward the construction of a differential transformer which is capable of continuous operation at high ambient pressures Notwithstanding a thorough inspection and performance test at the fact
44. used only with a gas Trichloroethylene has been declared toxic by Occupational Safety and Health Administration Use only with proper precautions MAINTENANCE 6 2 2413 9 Clean the diaphragm and cavity surfaces as described in Operation 6 and blow off all lint particles with a clean ear syringe or dust bulb Examine the assembly under a good light for clinging particles of lint Insert the preformed diaphragm in the cavity recess of the middle body 17 and place the bottom cap 20 upon the diaphragm while guiding the orienting pin into its hole Insert 4 screws equally spaced and pull them down evenly until it is certain that the sealing surfaces are in good contact With the assembly in an erect position check the motion of the diaphragm by pumping air against the lower fitting with the syringe or with a short piece of clean rubber tubing sealed off on the outer end and squeezed The motion will be visible by observing the end of the stem from above the transformer The motion of the stem should be truly axial with very little side motion surely not enough to interfere with the bore of the transformer Insert the remainder of the screws and snug them up lightly to the head If the motion of the stem previously observed was not axial but appeared to bob in one direction the screws on the opposite side of the direction of bob may be pulled up first and perhaps a little more than the others Sometimes this procedure will correct or red
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