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Geokon 4650 Instruction Manual

Vw settlement sensor
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Instruction Manual
Model 4650
VW Settlement Sensor
No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon
®
.
The information contained herein is believed to be accurate and reliable. However, Geokon
®
assumes no responsibility for errors,
omissions or misinterpretation. The information herein is subject to change without notification.
Copyright © 1984-2018 by Geokon
®
(Doc Rev S, 12/19/18)

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Summary of Contents for Geokon 4650

  • Page 1 Instruction Manual Model 4650 VW Settlement Sensor No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon ® The information contained herein is believed to be accurate and reliable. However, Geokon ®...
  • Page 3 Geokon or any breach of any warranty by Geokon shall not exceed the purchase price paid by the purchaser to Geokon 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.

  • Page 5: Table Of Contents

    A.2 T ) ......................17 HERMISTOR PPENDIX ALSO APPENDIX B. THERMISTOR TEMPERATURE DERIVATION ..............18 APPENDIX C. SPLICING 4650 SETTLEMENT SENSOR TUBING AND CABLE ........19 C.1 R ..........................19 EPLACING A RANSDUCER C.1.1 Liquid Line ............................... 19 C.1.2 Splicing the Cable ............................ 20 C.2 A...
  • Page 6 FIGURES Figure 1 - Typical Installation of Vibration Wire Settlement System ................1 Figure 2 - Sensor Details .............................. 1 Figure 3 - Reservoir Details ............................2 Figure 4 - Lemo Connector to GK-404 ......................... 6 Figure 5 - Live Readings – Raw Readings ........................7 Figure 6 - Typical Calibration Report ..........................11 Figure 7 - Flushing Apparatus .............................12 Figure 8 - In Situ Calibration Apparatus ........................14...

  • Page 7: General Description

    1. GENERAL DESCRIPTION The 4650 Settlement System is designed to measure the differential settlement between two points. A reservoir is located at a stable reference point and is connected to a sensor located at the settlement point by two liquid filled tubes. The sensor senses the pressure of liquid within the tube.

  • Page 8: Figure 3 - Reservoir Details

    Figure 3 shows details of a typical reservoir system. Two liquid filled tubes are provided for each sensor and more than one sensor can be connected to a single reservoir. The use of two liquid filled tubes permits the tubing to be flushed periodically to remove any accumulation of air bubbles.

  • Page 9: Installation Procedures

    2. INSTALLATION PROCEDURES Most installations are in fills and embankments where the sensor and cables are buried. Elsewhere the cables and sensors may be attached directly to structures undergoing settlement of heave. The reservoir location must always be at a higher elevation then the sensor and higher than any part of the liquid filled connecting tube.

  • Page 10: Installing The Reservoir, Connecting The Sensor Tubes And Vent Tube

    2.3 Installing the Reservoir, Connecting the Sensor Tubes and Vent Tube The reservoir should be installed on stable ground or at a location that can be level surveyed. The terminal housing should be affixed to stakes grouted firmly into the ground or preferably into a concrete pad poured at a location.

  • Page 11: Initial Readings

    12) Add fresh desiccant to the desiccant chamber (or the vent line manifold). 13) Add more liquid to the reservoir to bring up to the half-full point. A few drops of light oil added through the top of the reservoir will prevent evaporation from the liquid surface. 14) Reconnect the vent line fitting to the top of the reservoir.

  • Page 12: Taking Readings

    20 hours continuously on two AA batteries. It is designed for the readout of all Geokon vibrating wire gauges and transducers, and is capable of displaying the reading in either digits, frequency (Hz), period (µs), or microstrain (µε). The GK-404 also displays the temperature of the transducer (embedded thermistor) with a resolution of 0.1 °C.

  • Page 13: Gk-405 Readout Box

    3.2.2 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).

  • Page 14: Gk-403 Readout Box (Obsolete Model)

    3.3.2 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).

  • Page 15: Data Reduction

    The graph should also show the elevation of the fill above the sensor at the time of each reading. A plot of temperature can also be included. For the standard 4650 settlement system, using type 4500SV or 4500ALV transducers, the readings will get smaller as the sensors settle relative to the reservoir.

  • Page 16: Correction For Settlement Or Heave Of The Reservoir Terminal

    4.2 Correction for Settlement or Heave of the Reservoir Terminal Periodic level surveys should be made of the elevation of the concrete pad on which the reservoir terminal is located. Any measured settlement of the reservoir should be subtracted from the calculated sensor elevations.

  • Page 17: Figure 6 - Typical Calibration Report

    Figure 6 - Typical Calibration Report...

  • Page 18: Special Tools And Apparatus Required For Various Test Procedures

    Dye, added to the new flushing fluid, can be used to indicate when the flushing is complete. The best way to de-air a liquid is to use a Nold DeAerator (ask Geokon for more details). De- aired liquid is also available from Geokon in two gallon or five-gallon pressure tanks specially designed to prevent air from reaching the fluid.

  • Page 19: Purging The Vent Lines

    1) Close the shut off valve at the base of the reservoir. 2) Disconnect one of the tubes and then reconnect it to the base of a filling tank that is filled with de-aired liquid. 3) The second tube is disconnected and attached to the base of an auxiliary reservoir. (For tubes longer than 200 meters (650 feet) it is recommended that a vacuum pump be attached to the top of the auxiliary reservoir.

  • Page 20: In Situ Calibration

    8. IN SITU CALIBRATION A valuable feature of the Model 4650 settlement system is the ability to perform in situ calibrations. This is done by connecting an auxiliary reservoir to one of the fluid lines as shown in Figure 8.

  • Page 21: In Situ Zero Check

    9. IN SITU ZERO CHECK This procedure is not recommended as a regular procedure but only one to be undertaken if there is some serious doubt as to the zero stability of the sensor or to confirm a sudden or critical change in the amount of settlement which is causing concern.

  • Page 22: Trouble Shooting

    11. TROUBLE SHOOTING Faulty readings may show up as unstable, fluctuating readings, sudden large changes of readings or readings of 9999 on dataloggers, unrelated to physical phenomena. The first task should be to see if the fault lies with the readout device. If a datalogger is in use, try reading the sensors with a portable GK-403, GK-404, or GK-405 Readout box.

  • Page 23: Appendix A. Specifications

    APPENDIX A. SPECIFICATIONS A.1 Model 4650 VW Settlement Sensor Standard 7, 17 m Ranges Resolution 0.025% F.S. Sensor ±0.1% F.S. Accuracy Temperature -20 °C to +80 °C (-4 °F to +176 °F) Range Length x Reservoir: 152 x 51 mm (6 x 2") Diameter Sensor: 191 x 35 mm (7.5"...

  • Page 24: Appendix B. Thermistor Temperature Derivation

    APPENDIX B. THERMISTOR TEMPERATURE DERIVATION Thermistor Type: YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3 Resistance to Temperature Equation: A+B ( LnR ) +C(LnR) -273.2 Equation 3 - Resistance to Temperature Where; T = Temperature in °C. LnR = Natural Log of Thermistor Resistance A = 1.4051 ×...

  • Page 25: Appendix C. Splicing 4650 Settlement Sensor Tubing And Cable

    APPENDIX C. SPLICING 4650 SETTLEMENT SENSOR TUBING AND CABLE C.1 Replacing a Transducer The most critical aspect of this operation is making sure that no air is allowed to get into the liquid lines. The first step is to remove the faulty sensor by cutting both the liquid line and the cable from the faulty sensor using the procedures below.

  • Page 26: Splicing The Cable

    C.1.2 Splicing the Cable 1) Cut the cable from the faulty sensor and strip the jacket back approximately 50 to 75 millimeters (two to three inches). 2) The cable has four conductors and a drain wire (bare), as well as a barometer equalization tube.

  • Page 27: Appendix D. Swagelok Tube Fitting Instructions

    APPENDIX D. SWAGELOK TUBE FITTING INSTRUCTIONS These instructions apply to 25 mm (1") and smaller fittings. D.1 Installation 1) Fully insert the tube into the fitting until it bumps against the shoulder. Figure 9 - Tube Insertion 2) Rotate the nut until it is finger-tight. (For high-pressure applications as well as high-safety- factor systems, further tighten the nut until the tube will not turn by hand or move axially in the fitting.) 3) Mark the nut at the six o’clock position.

  • Page 28: Reassembly Instructions

    D.2 Reassembly Instructions Swagelok tube fittings 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.

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