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Geokon 4500MLP, Instruction Manual

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25 

 

Vibrating Wire Sensor Lead Grid - SAMPLE VALUES 

 

Red 

Black 

White 

Green 

Shield 

Red 

N/A 

≅180Ω

 

infinite 

infinite 

infinite 

Black 

≅180Ω

 

N/A 

infinite 

infinite 

infinite 

White 

infinite 

infinite 

N/A 

3000Ω

 at 

25°

C

 

infinite 

Green 

infinite 

infinite 

3000Ω

 at 

25°

C

 

N/A 

infinite 

Shield 

infinite 

infinite 

infinite 

infinite 

N/A 

Table 3 - Sample Resistance 

 
 

Vibrating Wire Sensor Lead Grid - SENSOR NAME/## : 

 

Red 

Black 

White 

Green 

Shield 

Red 

 

 

 

 

 

Black 

 

 

 

 

 

White 

 

 

 

 

 

Green 

 

 

 

 

 

Shield 

 

 

 

 

 

Table 4 - Resistance Work Sheet 

 

Summary of Contents for 4500MLP

Page 1: ... 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 2003 2017 by Geokon Inc REV I 10 23 17 ...

Page 2: ......

Page 3: ...re 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 t...

Page 4: ......

Page 5: ...perating the GK 404 15 4 2 GK 405 READOUT BOX 16 4 2 1 Connecting Sensors 16 4 2 2 Operating the GK 405 16 4 3 GK 403 READOUT BOX OBSOLETE MODEL 17 4 3 1 Connecting Sensors 17 4 3 2 Operating the GK 403 17 4 4 MEASURING TEMPERATURES 18 4 5 CHECKING THE CALIBRATION 18 5 DATA REDUCTION 20 5 1 PRESSURE CALCULATION 20 5 2 TEMPERATURE CORRECTION 21 5 3 BAROMETRIC CORRECTION REQUIRED ONLY ON UNVENTED TR...

Page 6: ...IGURE 17 LIVE READINGS RAW READINGS 16 FIGURE 18 SAMPLE CALIBRATION SHEET 19 TABLES TABLE 1 CEMENT BENTONITE WATER RATIOS 7 TABLE 2 ENGINEERING UNITS MULTIPLICATION FACTORS 21 TABLE 3 SAMPLE RESISTANCE 25 TABLE 4 RESISTANCE WORK SHEET 25 TABLE 5 VIBRATING WIRE PIEZOMETER SPECIFICATIONS 26 TABLE 6 STANDARD PIEZOMETER WIRING 26 TABLE 7 THERMISTOR RESISTANCE VERSUS TEMPERATURE 27 TABLE 8 THERMISTOR R...

Page 7: ...frequency is directly proportional to the pressure applied to the diaphragm Two coils one with a magnet insert the other with a pole piece insert are located close to the vibrating wire In use a pulse of varying frequency swept frequency is applied to the coils causing the wire to vibrate primarily at its resonant frequency When the excitation ends the wire continues to vibrate During vibration a ...

Page 8: ...onfiguration to its desired location This is shown schematically in Figure 2 and Figure 3 With the filter stones pressed against the wall of the borehole in this manner the borehole can be filled completely with bentonite cement grout without running the risk of getting the filter stone plugged with bentonite or having substantial amounts of the impervious bentonite interposed between the piezomet...

Page 9: ...m the syringe into the piezometer cavity 5 With the assembly still under water reconnect the nylon tube from the filter stone to the transducer Tighten the Swagelok per the instructions in Section 2 2 6 Keep the assembly under water until ready to lower into the borehole Caution Do not allow the piezometer to freeze once it has been filled with water 2 2 Swagelok Tube Fitting Instructions These in...

Page 10: ...ings may be disassembled and reassembled many times Warning Always depressurize the system before disassembling a Swagelok tube fitting 1 Prior to disassembly mark the tube at the back of the nut then make a line along the nut and fitting body flats These marks will be used during reassembly to ensure the nut is returned to its current position Figure 7 Marks for Reassembly 2 Disassemble the fitti...

Page 11: ...ill be used for all subsequent data reduction Generally the initial zero reading is obtained by reading the instrument prior to installation Vibrating Wire Piezometers differ from other types of pressure sensors in that they indicate a reading when no pressure is exerted on the sensor Calibration data is supplied with each gage a factory zero reading taken at a specific temperature and absolute ba...

Page 12: ...he temperature of the water in the borehole Use the thermistor inside the piezometer to measure the water temperature 3 Once the temperature has stabilized take a zero reading See Section 4 for readout instructions 4 Note the barometric pressure if possible or record the time for later referral to local weather station data 5 For maximum accuracy record the depth of the piezometer below the water ...

Page 13: ...mixes for strengths of 50 psi and 4 psi 50 PSI Grout for Medium to Hard Soils 4 PSI Grout for Soft Soils Amount Ratio by Weight Amount Ratio by Weight Water 30 gallons 2 5 75 gallons 6 6 Portland Cement 94 lb one sack 1 94 lb one sack 1 Bentonite 25 lb as required 0 3 39 lb as required 0 4 NOTES The 28 day compressive strength of this mix is about 50 psi similar to very stiff to hard clay The modu...

Page 14: ...reparing the grout pipe 1 Connect the sections of grout pipe together and lay them out along the ground 2 Mark the desired locations of the piezometers on the grout pipe at the calculated depths 3 Drill a single 7 32 or 1 4 inch drill hole diametrically through the pipe in each marked location Attaching the piezometers Each piezometer assembly is held to the grout pipe by means of a single 50 lb n...

Page 15: ...ring installation by two nylon zip ties supplied Making sure the grout pipe is between the platens and the cables from the lower piezometers are kept inside the zip tie and leaf springs attach the body of the piezometer to the grout pipe by passing the zip ties through the eyebolts in the platens and through the holes in the cutting tool Orient the tool in such a way that it will be above the asse...

Page 16: ...pneumatic tube from the piezometer to a bottle of CO2 CO2 can be obtained locally from any welding supply outlet The CO2 bottle should have a pressure regulator that is set to a pressure of at least 2 5 MPa 350 psi with the shutoff valve closed Figure 12 Figure 12 Pneumatic Cutter Equipment ...

Page 17: ...t above this elevation before the assembly is released The cutting tool is then removed from the drill hole and the next assembly is prepared for installation When lowering the subsequent piezometers down the hole feed the cables from the lower piezometers through the middle of the assembled piezometer rather than around the outside This will prevent the cables from interfering with the filter con...

Page 18: ... does not restrict the movement of the platens The grout pipe is assembled length by length while the piezometer assemblies each with its own pull pin are attached to it by taping the electrical cable to the grout pipe near the piezometer The grout pipe and piezometer assemblies can then be pushed down the hole as a unit When the final position is reached the pull pins are pulled activating the pl...

Page 19: ...d be a high quality twisted pair type with 100 shielding and an integral shield drain wire When splicing it is very important that the shield drain wires be spliced together Splice kits recommended by Geokon incorporate casts that are placed around the splice and then filled with epoxy to waterproof the connections When properly made this type of splice is equal or superior to the cable itself in ...

Page 20: ...ed method of lightning protection Terminal boxes available from Geokon can be ordered with lightning protection built in The terminal board used to make the gage connections has provision for the installation of plasma surge arrestors Lightning Arrestor Boards LAB 3 can also be incorporated into the terminal box The terminal box must be connected to an earth ground for these levels of protection t...

Page 21: ...he clips on the leads to the matching colors of the sensor conductors with blue representing the shield bare To turn the GK 404 on press the ON OFF button on the front panel of the unit The initial startup screen will display Geokon Inc GK 404 verX XX After approximately one second the GK 404 will start taking readings and display them based on the settings of the POS and MODE buttons The unit dis...

Page 22: ...locks into place Connecting Sensors with Bare Leads Attach the GK 403 2 flying leads to the bare leads of a Geokon vibrating wire sensor by connecting each of the clips on the leads to the matching colors of the sensor conductors with blue representing the shield bare 4 2 2 Operating the GK 405 Press the button labeled POWER ON BLUETOOTH A blue light will begin blinking signifying that the Remote ...

Page 23: ...until it locks into place Connecting Sensors with Bare Leads Attach the GK 403 2 flying leads to the bare leads of a Geokon vibrating wire sensor by connecting each of the clips on the leads to the matching colors of the sensor conductors with blue representing the shield bare 4 3 2 Operating the GK 403 1 Turn the display selector to position B or F 2 Turn the unit on 3 The readout will display th...

Page 24: ...ls use Appendix C Table 8 4 5 Checking the Calibration The following procedure can be used to verify the calibration factor as supplied on the calibration sheet 1 Saturate the filter stone and fill the space between it and the diaphragm with water see Section 2 1 2 Lower the piezometer to the bottom of a water filled borehole using the cable to measure the actual depth 3 Allow 15 to 20 minutes for...

Page 25: ...19 Figure 18 Sample Calibration Sheet ...

Page 26: ...0 2 FS the errors associated with nonlinearity are of minor consequence However for those situations requiring the highest degree of accuracy it may be desirable to use a second order polynomial to get a better fit of the data points The use of a second order polynomial is explained in Appendix D The instrument s calibration report a typical example of which is shown in Figure 18 shows the data fr...

Page 27: ...mperature Correction The materials used in the construction of Geokon s vibrating wire piezometers have been carefully selected to minimize thermal effects however most units still have a slight temperature coefficient Consult the calibration sheet supplied with the instrument to obtain the coefficient for the individual piezometer Since piezometers are normally installed in a tranquil and constan...

Page 28: ...erted remember to apply the same conversion to the calculated barometric correction Barometric pressure is usually recorded in inches of mercury The Conversion Factor for inches of mercury to PSI is 0 491 and from inches of mercury to kPa is 3 386 Table 2 lists other common Conversion Factors Equation 5 shows the pressure calculation with temperature and barometric correction applied Pcorrected R1...

Page 29: ...pped from the factory THIS SEAL SCREW MUST BE REMOVED BEFORE THE PIEZOMETER IS PUT INTO SERVICE The desiccant capsules are blue when fresh They will gradually turn pink as they absorb moisture When they have turned light pink in color they should be replaced Contact Geokon for replacement capsules 5 5 Environmental Factors Since the purpose of the piezometer installation is to monitor site conditi...

Page 30: ...ources of nearby electrical noise such as motors generators antennas or electrical cables Move the piezometer cable away from these sources if possible Contact the factory for available filtering and shielding equipment The Piezometer may have been damaged by overranging or shock Inspect the diaphragm and housing for damage The body of the Piezometer may be shorted to the shield Check the resistan...

Page 31: ... infinite infinite infinite White infinite infinite N A 3000Ω at 25 C infinite Green infinite infinite 3000Ω at 25 C N A infinite Shield infinite infinite infinite infinite N A Table 3 Sample Resistance Vibrating Wire Sensor Lead Grid SENSOR NAME Red Black White Green Shield Red Black White Green Shield Table 4 Resistance Work Sheet ...

Page 32: ...m 687 17 45 mm 437 11 10 mm 1 5 38 10 mm Length 5 25 133 35 mm 5 25 133 35 mm 5 25 133 35 mm 6 5 165 10 mm 6 5 165 10 mm Frequency Range Hz 1400 3500 1400 3500 1400 3500 1400 3500 1400 3500 Table 5 Vibrating Wire Piezometer Specifications Accuracy of Geokon test apparatus 0 1 Contact Geokon for specific application information Notes 1 Accuracy of test apparatus 0 05 2 Other ranges available upon r...

Page 33: ...2 83 107 9 123 77 66K 36 8006 4 1363 44 331 5 84 105 2 124 72 81K 35 7618 5 1310 45 321 2 85 102 5 125 68 30K 34 7252 6 1260 46 311 3 86 99 9 126 64 09K 33 6905 7 1212 47 301 7 87 97 3 127 60 17K 32 6576 8 1167 48 292 4 88 94 9 128 56 51K 31 6265 9 1123 49 283 5 89 92 5 129 53 10K 30 5971 10 1081 50 274 9 90 90 2 130 49 91K 29 5692 11 1040 51 266 6 91 87 9 131 46 94K 28 5427 12 1002 52 258 6 92 85...

Page 34: ...34 64 4 903 117 837 170 09 0 09 0 03 25 8200 9 012 731 893 25 00 0 00 0 00 175 122 1 4 805 110 927 175 08 0 08 0 03 30 6721 54 8 813 684 514 30 01 0 01 0 00 180 110 95 4 709 104 426 180 07 0 07 0 02 35 5540 74 8 620 640 478 35 01 0 01 0 00 185 100 94 4 615 98 261 185 10 0 10 0 04 40 4592 8 432 599 519 40 02 0 02 0 01 190 92 086 4 523 92 512 190 09 0 09 0 03 45 3825 3 8 249 561 392 45 02 0 02 0 01 ...

Page 35: ...P F S x 100 Equation 9 Linearity Calculation Note The linearity is calculated using the regression zero for R0 shown on the sheet For example when P 420 kPa G R1 R0 0 1795 6749 9082 gives a calculated pressure of 418 8 kPa The error is 1 2 kPa equal to 122 mm of water Whereas the polynomial expression gives a calculated pressure of A 6749 2 B 6749 1595 7 420 02 kPa and the actual error is only 0 0...

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