4420 Crackmeter
Contents
1. 2 TABLE 1 CRACKMETER ANCHOR SPACING 5 2220020 200 222 10 000000000 3 TABLE 2 CRACKMETER READING 3 FIGURE 4 INSTALLATION USING WELDABLE FIXTURES 0 cccccessceececsseceessecsccesscecsecesseecsuscesssecnsecesseeenseeesese 4 FIGURE 5 INSTALLATION USING GROUTABLE 85 2 02 0 2 0000000 0000 4 FIGURE 6 INSTALLATION USING EXPANSION ANCHORS 0 2 0 0 0 20 00 0000000 5 FIGURE 7 TYPICAL COVER PLATE 6 FIGURE 8 LIGHTNING PROTECTION 1 202 06 000100100 0 7 FIGURE 9 GK405 READOUT gt 9 EQUATION Ts DIGITS GAEGULATION 2 ches tete oett reet t eve ee et aS 10 EQUATION 2 DEFORMATION 2 02 000 0010000000000 teretes stresses 10 TABLE 3 ENGINEERING UNITS CONVERSION MULTIPLIERS esee 10 FIGURE 10 TYPICAL CRACKMETER CALIBRATION 2020 00 404 1 1010 00 00 01800 11 EQUATION THERMALLY CORRECTED DEFORMATION 0200 2400040000 0000 nere enr ente 12 EQUATION 4 THERMAL COEFFICIENT CALCULATION cernerent en tre2. esse e estet ee esse ee 1 4420 ence rete sca BOT eie cod a ES 1 VW CRACK METER dee 1 1 INTRODUCTION epe EC 1 2 EVER WMULOPESES 2 2 1 PREEMINARY LESTS eret eere eter E teet eere We eder dente re ters 2 2 2 CRACKMETER INSTAELATION eec echte teet are str ERE 2 2 2 1 Installation using Weldable 4 2 2 2 Installation using Groutable Anchors sse eene 4 2 2 3 Installation USING Expansion 5 2 3 PROTECTION FROM MECHANICAL DAMAGE 000 6 THE STANDARD COVER PLATE IS LONG ENOUGH TO COVER THE TWO INCH RANGE CRACKMETER LONGER RANGE CRACKMETERS MUST USE TWO OVERLAPPING COVER PLATES BOLTED 2 6 2 4 CABLE INSTAEEATION cert ecrire deeem dre deer en 6 25 ort Pe eee een e ER 6 2 6 5 7 3 TAKING READINGS eV Vae E Te de Us oat eo aln De aao pedo n 8 3 1 OPERATION OF THE GK 403 READOUT 8 3 2 OPERATION OF THE GK404 READOUT
3. 8 3 3 OPERATION OF THE GK 405 READOUT 9 3 4 MEASURING 9 4 DATA REDUCTION p HU 10 4 1 DEFORMATION CALCULATION c0csssesessssssssesssscsssescscsescssecssscesscesecsessessesessesecseesssesesesesesssessseseseseseeeeees 10 4 2 TEMPERATURE CORRECTION s0cscseseeesesesesecscssscscsesescsesesescssesssseecsesesceesesesessesseeseseseseesseseseseseseseseseseeees 12 4 3 ENVIRONMENTAL 13 5 EHOUBRNISLO OU LCS 13 APPENDIX A SPECIFICATIONS o ro ga aera at oe eva Po eee ve save euo ve VV Veo v eU nado UE aaa DEUS Tene 15 AT MODEE4420 CRACKMBTER D noie 15 AC THER MISTOR iet E oi 16 APPENDIX THERMISTOR TEMPERATURE DERIVATION ccsssccsssssscesssscccsssccesssecssssssccessnee 16 APPENDIX 3D 17 LIST of FIGURES TABLES and EQUATIONS Page FIGURE 1 MODEL 4420 1 50 100 150 200 300 VIBRATING WIRE 1 FIGURE 2 MODEL 4420 1 12 25 DETAIL 2 02020 02 2 2 006000000000000000000 1 FIGURE ANCHOR TYPES WITH 1 1
4. 20 to 80 C 5 to 175 F 1200 2800 Hz 180 Q 100 2 twisted pair 4 conductor 22 AWG Foil shield PVC jacket nominal OD 6 3 mm 0 250 Red and Black are the VW Sensor White and Green the Thermistor 325 333m 406m 543 686 mm 740 967m mm m m mm 27 0 mm 38 1 12 8 13 1 16 21 4 29 2 i 31 75 x 25 4 mm 1 25 x 1 180g 175g 197g 297g 355g 5 75 5 6 63 9 502 11 4 02 OZ OZ OZ Table A 1 Crackmeter Specifications Minimum greater resolution possible depending on readout Depends on application 3 Polyurethane jacket cable available 16 A 2 Thermistor Range 80 150 Accuracy 0 5 C APPENDIX THERMISTOR TEMPERATURE DERIVATION Thermistor Type YSI 44005 Dale 1C3001 B3 Alpha 13A3001 B3 Resistance to Temperature Equation 1 T 3 2732 A B LnR C LnR Equation B 1 Convert Thermistor Resistance to Temperature Where T Temperature in C LnR Natural Log of Thermistor Resistance 1 4051 x 10 3 coefficients calculated over the 50 to 150 C span B 2 369 10 4 C 1 019 x 1077 Table B 1 Thermistor Resistance versus Temperature APPENDIX C 3D Arrays Monitoring crack movements in three dimensions requires an array of three crack meters One such array is shown in Figure 11 TYPICAL 3D ARRAY PLAN VIEW TYPICAL 3D ARRAY SIDE VIEW Figure 11 Typical 3D Array 18
5. The World Leader in Vibrating Wire Technology 48 Spencer Street Lebanon NH 03766 USA Tel 603 448 1562 Fax 603 448 3216 E mail geokon geokon com http www geokon com Instruction Manual Model 4420 VW Crackmeter cc Xx No part of this instruction manual may be reproduced by any means without the written consent of Geokon Inc The information contained herein is believed to be accurate and reliable However Geokon Inc assumes no responsibility for errors omissions or misinterpretation The information herein is subject to change without notification Copyright O 1986 1996 2004 2006 2007 2008 2012 2013 by Geokon Inc Doc Rev Q 6 13 Warranty Statement Geokon Inc warrants its products to be free of defects in materials and workmanship under normal use and service for a period of 13 months from date of purchase If the unit should malfunction it must be returned to the factory for evaluation freight prepaid Upon examination by Geokon if the unit is found to be defective it will be repaired or replaced at no charge However the WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of being damaged as a result of excessive corrosion or current heat moisture or vibration improper specification misapplication misuse or other operating conditions outside of Geokon s control Components which wear or which are damaged by misuse are not warranted This includes fuse
6. The ends of the crack meters are fixed to brackets and these brackets are bolted to anchor pads made from a small stainless steel welded to a short length of 3 rebar The rebars are grouted into short boreholes 3 8 diameter x 1 1 4 deep hole on each side of the crack to be measured and at a spacing chosen from Table 1 in Section 2 The actual height of the crackmeters above the surface should be chosen with regard to the clearance necessary to accommodate the anticipated movements Refer to the instructions in Sections 2 2 2 for groutable anchors and Section 2 2 3 for drop in expansion anchors An alternative version is available where the vertical element is replaced by a cantilever arrangement the cantilever having a Model 4150 strain gage attached to measure shear movements TYPICAL 3D ARRAY CANTILEVER VERSION PLAN VIEW Figure 12 3D Array Cantilever Version Instruction for Installing the Cantilever Drill a 3 8 diameter x 1 1 4 deep hole on each side of the crack to be measured at a spacing of 10 5 267mm Clean out the drill cuttings and place the drop in anchor in the hole Place the anchor setting tool into the anchor and strike the drive pin with several sharp hammer blows Now screw the target plate into one of the threaded drop in anchor holes using loctite cement on the threads until it is tight in the anchor Next place the crackmeter over the other hole and screw the supplied cap screw into the drop in a
7. 60 Deorrected 0 861 4 3 Environmental Factors Since the purpose of the crackmeter installation is to monitor site conditions factors which may affect these conditions should always be observed and recorded Seemingly minor effects may have a real influence on the behavior of the structure being monitored and may give an early indication of potential problems Some of these factors include but are not limited to blasting rainfall tidal levels excavation and fill levels and sequences traffic temperature and barometric changes changes in personnel nearby construction activities seasonal changes etc 5 TROUBLESHOOTING Maintenance and troubleshooting of Geokon Vibrating Wire Crackmeters is confined to periodic checks of cable connections and maintenance of terminals The transducers themselves are sealed and cannot be opened for inspection However note the following problems and possible solutions should difficulties arise Consult the factory for additional troubleshooting help Symptom Crackmeter Readings are Unstable Y 1 the readout box position set correctly If using a datalogger to record readings automatically are the swept frequency excitation settings correct Y sthe transducer shaft positioned outside the specified range either extension or retraction of the instrument Note that when the transducer shaft is fully retracted with the alignment pin inside the alignment slot Figure 1 the readings will likely
8. A 1 11026E 08 B 0 004345 C 9 7486 inches Linear Gage Factor 0 0001755 digit Polynomial Gage Factors 4 37111E 10 B 0 0001711 C 0 38380 Calculated Displacement Linear D G R Ry Polynomial D AR BR Refer to manual for temperature correction information Function Test at Shipment GK 401 Pos B 4795 Dates 19 2005 The above instrument was found to be in tolerance in all operating ranges The above named instrument has been calibrated by comparison with standards traceable to the NIST in compliance with ANSI 7540 1 This report shall not be reproduced except in full without written permission of Geokon Inc Figure 10 Typical Crackmeter Calibration Sheet 12 4 2 Temperature Correction The Model 4420 Vibrating Wire Crackmeters have a small coefficient of thermal expansion so in many cases correction may not be necessary However if maximum accuracy is desired or the temperature changes are extreme gt 10 C corrections may be applied The temperature coefficient of the mass or member to which the Crackmeter is attached should also be taken into account By correcting the transducer for temperature changes the temperature coefficient of the mass or member may be distinguished The following equation applies Dcorrected Ro G T4 x Equation 3 Thermally Corrected Deformation Calculation Where R4 is the current reading is th
9. be exercised when installing instrument cables to keep them as far away as possible from sources of electrical interference such as power lines generators motors transformers arc welders etc Cables should never be buried or run with AC power lines The instrument cables will pick up the 50 or 60 Hz or other frequency noise from the power cable and this will likely cause a problem obtaining a stable reading Contact the factory concerning filtering options available for use with the Geokon dataloggers and readouts should difficulties arise 2 6 Lightning Protection The Model 4420 Vibrating Wire Crackmeter unlike numerous other types of instrumentation available from Geokon do not have any integral lightning protection components i e transzorbs or plasma surge arrestors Usually this is not a problem however if the instrument cable is exposed it may be appropriate to install lightning protection components as the transient could travel down the cable to the gage and possibly destroy it Note the following suggestions If the gage is connected to a terminal box or multiplexer components such as plasma surge arrestors spark gaps may be installed in the terminal box multiplexer to provide a measure of transient protection Terminal boxes and multiplexers available from Geokon provide locations for installation of these components Lighting arrestor boards and enclosures are available from Geokon that install near the instrument Th
10. be unstable because the vibrating wire is now under tensioned Y 15 there a source of electrical noise nearby Most probable sources of electrical noise are motors generators and antennas 14 Symptom Crackmeter Fails to Read Y Is the cable cut or crushed This be checked with an ohmmeter Nominal resistance between the two transducer leads usually red and black leads is 1800 10 O Remember to add cable resistance when checking 22 AWG stranded copper leads are approximately 14 7Q 1000 or 48 50 If the resistance reads infinite or very high gt 1 megohm a cut wire must be suspected If the resistance reads very low 100 a short in the cable is likely Splicing kits and instructions are available from the factory to repair broken or shorted cables Consult the factory for additional information v Does the readout or datalogger work with another transducer If not the readout or datalogger may be malfunctioning 15 APPENDIX A SPECIFICATIONS A 1 Model 4420 Crackmeter Range Resolution Linearity Thermal Zero Shift 2 Stability Overrange Temperatur e Range Frequency Range Coil Resistance Cable Type Cable Wiring Code Length mid range end to end Coil Assembly Dimension S length x OD Weight Notes 200m 300m m 8 m 12 0 025 FSR 0 25 FSR lt 0 05 FSR C lt 0 2 yr under static conditions 115 FSR
11. ble anchors If installing the instrument at the mid range position leave the nylon tie installed see Figure 1 that secures the transducer shaft Fill the holes with grout or epoxy and push the anchors in until the tops are flush with the surface For holes drilled overhead use a quick setting grout or epoxy 3 Tighten the set screws after the grout or epoxy has set Remove the nylon tie 4 Check the reading with a portable readout Use Table 2 or the readings on the calibration sheet to check the position Installation complete 2 2 3 Installation using Expansion Anchors Spacer Spacer Expansion Anchor Setting Distance Figure 6 Installation using Expansion Anchors Installation instructions See section 2 2 for special instructions re Models 4420 1 12 and 4420 1 25 1 Determine proper setting distance using figures from Table 1 or the readings on the calibration sheet Using a masonry drill or other suitable equipment drill two 3 8 inch or 10mm diameter holes 114 32mm deep at the proper locations 2 Insert the expansion anchors into the holes with the slotted end down and then insert the setting tool provided small end first into the anchor and expand the anchor by hitting the large end of the setting tool with several sharp hammer blows 3 Remove the nylon tie securing the transducer shaft Push the cap screws through the swivel bearings and spacers on each end of the crackmeter then t
12. body serve as a guide for alignment Special note regarding installation of the Model s 4420 1 12 or 4420 1 25 If the reading is not in the proper range after installation additional adjustment is provided for by the inclusion of a threaded extension and locking nut as depicted in Figure 2 In order to use this feature the transducer needs to be attached at the coil assembly end to the anchor Position but do not attach the opposite end of the Crackmeter over the threaded hole of the anchor If the reading is not in the proper range see Table 2 loosen the locking nut Figure 2 and rotate the threaded rod which carries the rod end swivel bearing in or out of the end of the Transducer Shaft until the desired spacing and initial reading has been achieved The transducer shaft itself must not be rotated It should be gripped while rotating the rod end swivel bearing After adjusting align the hole in the rod end swivel bearing over the anchor place the cap screw through the hole and through the 1 2 inch spacer and then tighten the cap screw into the anchor 2 2 1 Installation using Weldable Fixtures Weld Weldable or Epoxy Mounting Pad 4 Fissure Setting Distance Weldable or Epoxy Mounting Pad Figure 4 Installation using Weldable Fixtures Installation instructions See section 2 2 for special instructions re Models 4420 1 12 and 4420 1 25 1 Determine proper setting distance using
13. ctions for each of the above three anchors Extensions Compressions 4420 5 12 8 12 6 13 0 4420 1 13 1 12 6 13 6 406 mm 381 mm 432 mm 4420 2 16 15 17 4420 4 21 4 19 4 23 3 4420 6 27 0 24 1 30 0 4420 8 29 1 25 2 33 1 4420 12 38 1 32 2 44 Table 1 Crackmeter Anchor Spacing Distances When setting the gage position using a portable readout see section 3 use the reading ranges in Table 2 to determine the proper position Approx Mid Range Approx Reading to Approx Reading to Reading Monitor Extensions Monitor Compressions 4500 5000 2500 3000 6500 7000 Table 2 Crackmeter Reading Ranges Note also that the calibration sheet Figure 8 supplied with the Crackmeter shows actual readings at zero 25 50 75 and 100 of the range of extension These readings can be used as a guide to set the Crackmeter in any part of it s range either in anticipation of closure or opening of the crack The Crackmeter can be extended until the desired reading see Section 3 for readout instructions is obtained and then held in this position while the distance between the anchor points threaded cap screws inside the swivel bearings see Figure 1 is measured This measurement can then serve as a spacing guide for drilling or welding the anchor points Caution Do not rotate the shaft of the Crackmeter This may cause irreparable damage to the instrument The alignment pin on the transducer shaft and slot on the
14. e 12 TABLE 4 THERMAL COEFFICIENT CALCULATION CONSTANTS 12 TABLE A 1 CRACKMETER SPECIFICATIONS 15 EQUATION B 1 CONVERT THERMISTOR RESISTANCE TO TEMPERATURE 16 TABLE B 1 THERMISTOR RESISTANCE VERSUS TEMPERATURE 2220 0 40 0 0 0 0000 00000000 16 BIGURE 3D ARRAY E 48 19 t s rode e ILE A 17 FIGURE 12 3D ARRAY CANTILEVER VERSION ccccccccsssssscecececeessaececececsessasececececeeseaeaeceesesesesaaeceeececsessaasaeeess 18 1 INTRODUCTION Geokon Model 4420 Vibrating Wire Crackmeters are designed to measure movement across joints such as the construction joints in buildings bridges pipelines dams etc tension cracks in soils and joints in rock and concrete The instrument consists of a vibrating wire sensing element in series with a heat treated stress relieved spring which is connected to the wire at one end and a connecting rod at the other The unit is fully sealed and operates at pressures of up to 250 psi As the connecting rod is pulled out from the gage body the spring is elongated causing an increase in tension which is sensed by the vibrating wire element The tension in the wire is directly proportional to the extension hence the opening of the joint can be determined very accurately by measuring the strain change with the vibrating wire readout box Instrument Cable Coil amp Thermi
15. e enclosure has a removable top so in the event the protection board LAB 3 is damaged the user may service the components or replace the board A connection is made between this enclosure and earth ground to facilitate the passing of transients away from the gage See Figure 8 Consult the factory for additional information on these or alternate lightning protection schemes Plasma surge arrestors can be epoxy potted into the gage cable close to the sensor A ground strap would connect the surge arrestor to earth ground either a grounding stake or other suitable earth ground Structure we Box Multiplexer Crack Model 4420 Crackmeter RW Instrument Cable usually buried LAB 3 Enclosure LAB 3 Board Surface 1 Ground Connections Figure 8 Lightning Protection Scheme 3 TAKING READINGS 3 1 Operation of the GK 403 Readout Box The GK 403 can store gage readings and also apply calibration factors to convert readings to engineering units Consult the GK 403 Instruction Manual for additional information on Mode G of the Readout The following instructions will explain taking gage measurements using Modes B and F similar to the GK 401 switch positions B and F Connect the Readout using the flying leads or in the case of a terminal station with a connector The red and black clips are for the vibrating wire gage the white and green clips are for t
16. e initial reading G is the linear gage factor T4 is the current temperature is the initial temperature K is the thermal coefficient see Equation 4 Tests have determined that the thermal coefficient K changes with the position of the transducer shaft Hence the first step in the temperature correction process is determination of the proper thermal coefficient based on the following equation K R4 x M B x G Equation 4 Thermal Coefficient Calculation Where R4 is the current reading M is the multiplier from Table 4 B is the constant from Table 4 G is the linear gage factor from the supplied calibration sheet Model 4420 6 mm 4420 12 4420 25 4420 50 4420 100 4420 150 4420 0 25 mm mm mm mm 4420 0 5 4420 1 4420 2 4420 4 4420 6 Multiplier 0 00073 0 000295 0 000301 0 000330 0 000192 0 000216 M Constant B 0 583 1 724 0 911 0 415 0 669 0 491 Model 4420 200 4420 300 4420 8 4420 12 M Constant B 0 240 054 J Table 4 Thermal Coefficient Calculation Constants 13 Consider the following example using a Model 4420 25 mm Crackmeter Ro 4773 digits R1 4589 digits Tg 20 3 C 32 9 G 0 00555 mm digit 4589 0 000301 0 911 0 00555 0 0127 Dcorrected R1 Hg C T1 Deorrected 4589 4773 x 0 00555 32 9 20 3 0 0127 Dcorrected 184 0 00555 0 160 Deorrected 1 021 0 1
17. er is equipped with a thermistor for reading temperature The thermistor gives a varying resistance output as the temperature changes Usually the white and green leads are connected to the internal thermistor The GK 401 readout box will not read temperatures an ohmmeter is required 10 1 Connect the ohmmeter to the two thermistor leads coming from the Crackmeter Since the resistance changes with temperature are so large the effect of cable resistance is usually insignificant 2 Look up the temperature for the measured resistance in Table B 1 Alternately the temperature could be calculated using Equation B 1 Note The GK 403 GK 404 and GK 405 readout boxes will all read the thermistor and display temperature in C automatically 4 DATA REDUCTION 4 1 Deformation Calculation The basic units utilized by Geokon for measurement and reduction of data from Vibrating Wire Crackmeters are digits Calculation of digits is based on the following equation E Hz Digits Period 1000 Equation 1 Digits Calculation To convert digits to deformation the following equation applies 2 Jo or Digits Duncorrected Ro x F Equation 2 Deformation Calculation Where R4 is the current reading Rg is the initial reading usually obtained at installation see section 2 4 G is thegage factor usually millimeters or inches per digit see Figure 10 F is an optional engineering units conversion facto
18. eter in tension thereby helping to protect it during shipping Remove this PVC split sleeve or dowel pin before proceeding Connect the gage to the Readout to take a reading see section 3 The reading should be stable and in the range of 4000 to 5000 Checks of electrical continuity can also be made using an ohmmeter Resistance between the gage leads should be approximately 180 ohms 10 ohms Remember to add cable resistance when checking 22 AWG stranded copper leads are approximately 14 7 2 1000 or 48 50 km multiply by 2 for both directions Between the green and white should be approximately 3000 ohms at 25 see Table B 1 and between any conductor and the shield should exceed 2 megohms 2 2 Crackmeter Installation Three types of anchors are available from the factory for installing the Model 4420 Vibrating Wire Crackmeter 1 4 20 Thread amp t 1 1 000 x 25 4 mm t 4 0 375 9 5 mm 0 375 9 5 mm Weldable Mounting Fixture Expansion Anchor Groutable Anchor Figure 3 Anchor Types with Dimensions The weldable fixture is designed to install the Crackmeter on steel members The machine bolt expansion anchors and groutable anchors are used to install the Crackmeter on concrete or rock The anchors are installed at the appropriate spacing distance see Table 1 depending on the anticipated direction of movement extensions or compressions The following three sections detail instru
19. figures in Table 1 or the readings on the calibration sheet Prepare the surface grinding sanding etc of the steel around the area of each weldable fixture 2 Locate the welding fixtures on prepared surfaces check spacing again and tack weld to the member 3 Remove the nylon tie securing the transducer shaft Thread the cap screw through the swivel bearing and through the 7 inch spacer on each end Then tighten the cap screws into the welding fixtures 4 Check the reading with a portable readout Use Table 2 or the readings on the calibration sheet to check the position The installation is now complete 2 2 2 Installation using Groutable Anchors Spacer L 5 Setting Distance Spacer Groutable Anchor Grout or Epoxy Figure 5 Installation using Groutable Anchors Installation instructions anton SS 5555666 AW Mm UNS See section 2 2 for special instructions re Models 4420 1 12 and 4420 1 25 1 Determine proper setting distance using figures from Table 1 or the readings on the calibration sheet Using a hammer drill or other suitable equipment drill two 1 2 holes approximately 3 deep at the proper locations Shorter holes may be drilled if the anchors are cut down accordingly 2 Assemble the Crackmeter with cap screws threaded through the swivel bearings and the spacers and threaded loosely into the grouta
20. he thermistor and the blue for the shield drain wire 1 Turn the display selector to position B or F Readout is in digits Equation 4 1 2 Turn the unit on and a reading will appear in the front display window The last digit may change one or two digits while reading Press the Store button to record the value displayed If the no reading displays or the reading is unstable see section 5 for troubleshooting suggestions The thermistor will be read and output directly in degrees centigrade 3 The unit will automatically turn itself off after approximately 2 minutes to conserve power 3 2 Operation of the GK404 Readout Box The GK404 is a palm sized readout box which displays the Vibrating wire value and the temperature in degrees centigrade The GK 404 Vibrating Wire Readout arrives with a patch cord for connecting to the vibrating wire gages One end will consist of a 5 pin plug for connecting to the respective socket on the bottom of the GK 404 enclosure The other end will consist of 5 leads terminated with alligator clips Note the colors of the alligator clips are red black green white and blue The colors represent the positive vibrating wire gage lead red negative vibrating wire gage lead black positive thermistor lead green negative thermistor lead white and transducer cable drain wire blue The clips should be connected to their respectively colored leads from the vibrating wire gage cable Use the POS Pos
21. ighten the cap screws into the anchors 4 Check the reading with a portable readout Use Table 2 or the readings on the calibration sheet to check the position Installation complete 2 3 Protection from mechanical damage can be had by using the cover plates made by Geokon See Figure 7 Two 3 8 x 2 inch long hex head bolts which will hold the cover plates should be anchored in place using either groutable or expansion anchors The special cover plates are made from sheet steel formed into a channel shape To get the correct spacing for the bolts a spacer jig is available or the cover plate can be flipped over on its back and the holes in the cover plate used to mark the bolt locations The holes are spaced at a nominal 21 inches 530mm apart one hole is slotted so that the spacing is not critical Figure 7 Typical Cover Plate Installation The standard cover plate is long enough to cover the two inch range crackmeter longer range crackmeters must use two overlapping cover plates bolted together 2 4 Cable Installation The cable should be routed in such a way so as to minimize the possibility of damage due to moving equipment debris or other causes Cables may be spliced to lengthen them without affecting gage readings Always waterproof the splice completely preferably using an epoxy based splice kit such the 3M Scotchcast model 82 A1 These kits are available from the factory 2 5 Electrical Noise Care should
22. ition button to select position B and the MODE button to select Dg digits Other functions can be selected as described in the GK404 Manual The GK 404 will continue to take measurements and display the readings until the OFF button is pushed or if enabled when the automatic Power Off timer shuts the GK 404 off The GK 404 continuously monitors the status of the 2 1 5V AA cells and when their combined voltage drops to 2V the message Batteries Low is displayed on the screen A fresh set of 1 5V AA batteries should be installed at this point 3 3 Operation of the GK 405 Readout Box The GK 405 Vibrating Wire Readout is made up of two components e the Readout Unit consisting of a Windows Mobile handheld PC running the GK 405 Vibrating Wire Readout Application e the GK 405 Remote Module which is housed in a weather proof enclosure and connects to the vibrating wire sensor by means of 1 Flying leads with alligator type clips when the sensor cable terminates in bare wires or 2 by means of a 10 pin connector The two components communicate wirelessly using Bluetooth a reliable digital communications protocol The Readout Unit can operate from the cradle of the Remote Module see Figure 9 or if more convenient can be removed and operated up to 20 meters from the Remote Module Figure 9 GK405 Readout Unit For further details consult the GK405 Instruction Manual 3 4 Measuring Temperatures Each Vibrating Wire Crackmet
23. nchor while aligning it with the target and while also making sure that the cantilever 19 does not become overstressed This can be avoided by backing off the jam nut and unscrewing the pointed threaded rod Tighten the clamping cap screw Now connect the readout box to the cable and observe the transducer output in pos B With no contact with the target the output will be between 1800 and 2500 digits This will be your rough zero point If all the anticipated displacement is seen as the cantilever moving down with reference to the target set the zero position at 3000 digits by turning the threaded rod on the cantilever tip until the reading is achieved afterwhich the locknut may be tightened If all the movement is seen as moving up set at 10 000 digits For mid range set at 7000 digits The cable is tied to the sensor with tywraps but should be secured near the carckmeter to prevent any strain on the small gage leadwires areas of high traffic the gage should be protected by a cover plate
24. r see Table 3 From Tol 1 12 0 03937 0 3937 39 37 Milimeters 254 3048 1 10 1000 Meters 0 0254 0 3048 0001 1 Table 3 Engineering Units Conversion Multipliers For example the initial reading Ro at installation of a crackmeter is 2500 digits The current reading R4 is 6000 The gage factor is 0 004457 mm digit The deformation change is Duncorrected 6000 2500 x 0 004457 415 60 mm Note that increasing readings digits indicate increasing extension To use the Polynomial Gage factors given on the Calibration Sheet use the value of Ro and Gage Factors A and B with D set to zero to calculate the new value of C then substitute the new value of and use A B and the new value of C to calculate the displacement D 11 GE OKON 48 Spencer St Lebanon N H 03766 USA Vibrating Wire Displacement Transducer Calibration Report Range 25mm Calibration Date September 01 2005 Serial Number 05 8389 Temperature 23 6 C Cal Std Control Numbers 529 406 344 057 Calibration Instruction CI 4400 Rev C Technician GK 401 Reading Position Actual Gage Gage Average Calculated Calculated Error Displacement Reading Reading Gage Displacement Polynomial mm Ist Cycle 2nd Cycle Reading i Polynomial ES mm Linear Gage Factor 0 004457 mm digit Regression Zero 2241 Polynomial Gage Factors
25. s and batteries Geokon manufactures scientific instruments whose misuse is potentially dangerous The instruments are intended to be installed and used only by qualified personnel There are no warranties except as stated herein There are no other warranties expressed or implied including but not limited to the implied warranties of merchantability and of fitness for a particular purpose Geokon Inc is not responsible for any damages or losses caused to other equipment whether direct indirect incidental special or consequential which the purchaser may experience as a result of the installation or use of the product The buyer s sole remedy for any breach of this agreement by Geokon Inc or any breach of any warranty by Geokon Inc shall not exceed the purchase price paid by the purchaser to Geokon Inc for the unit or units or equipment directly affected by such breach Under no circumstances will Geokon reimburse the claimant for loss incurred in removing and or reinstalling equipment Every precaution for accuracy has been taken in the preparation of manuals and or software however Geokon Inc neither assumes responsibility for any omissions or errors that may appear nor assumes liability for any damages or losses that result from the use of the products in accordance with the information contained in the manual or software TABLE of CONTENTS Page Instruction MANUAL 22222 000000 hee eee ne nee hetes
26. stor Housing Rod End 4 conductor 22 AWG Swivel Bearin g Transducer Housing Transducer Shaft Cap Screw CX Spacer Spacer Alignment Slot Alignment Pin Cap Screw Cap Screw 1 4 20 thread Elbow Joint Coupling 1 4 20 thread Figure 1 Model 4420 1 50 100 150 200 300 Vibrating Wire Crackmeter The Model s 4420 12 and 4420 25 differ slightly from the standard Crackmeter in that they provide for adjustment of the setting distance with a threaded extension rod and locking nut Dowel Pin for Shipment Rod End Swivel Bearing Transducer Housing Transducer Shaft Cap Screw Spacer Alignment Slot Coupling x Cap Screw Alignment Pin Locking Nut 1 4 20 thread Figure 2 Model 4420 1 12 25 Detail CAUTION Do not rotate the shaft of the Crackmeter more than 180 degrees This may cause irreparable damage to the instrument The alignment pin on the transducer shaft and slot on the body serve as a guide for alignment Do not under any circumstamces extend the crackmeter beyond its working range 2 INSTALLATION 2 1 Preliminary Tests Upon receipt of the instrument the gage should be checked for proper operation including the thermistor The Crackmeter normally arrives with it s shaft secured at approximately 50 of it s range by either a split PVC sleeve for crackmeters over 100mm 4 inch range or a dowel pin held in place by a piece of tape see Figure 2 These devices hold the crackm
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