Geokon 4675LV User manual

Instruction Manual
Model 4675LV
Weir Monitor
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 © 1991, 2004, 2006, 2011, 2012, 2013 by Geokon, Inc.
(Doc Rev H, 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 fuses 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.

Contents
SPECIFICATIONS.................................................................................................................................................1
2. INSTALLATION PROCEDURES....................................................................................................................2
2.1. PRELIMINARY CHECKS ....................................................................................................................................2
2.2 INSTALLATION..................................................................................................................................................2
3. TAKING READINGS.........................................................................................................................................4
3.1. OPERATION OF THE GK-403 READOUT BOX...................................................................................................4
3.2. OPERATION OF THE GK404 READOUT BOX....................................................................................................5
3.3. OPERATION OF THE GK405 READOUT BOX....................................................................................................5
3.4. MEASURING TEMPERATURES..........................................................................................................................6
4. DATA REDUCTION ..........................................................................................................................................7
4.1 DETERMINATION OF WATER ELEVATION.........................................................................................................7
4.2 CORRECTIONS FOR TEMPERATURE CHANGES...................................................................................................9
5. MAINTENANCE ..............................................................................................................................................10
5.1 MOISTURE TRAP.............................................................................................................................................10
5.2 WEIGHT MAINTENANCE .................................................................................................................................10
5.3 SENSOR ..........................................................................................................................................................11
6. TROUBLE SHOOTING...................................................................................................................................11
APPENDIX 1 THERMISTOR LINEARIZATION USING STEINHART AND HART LOG EQUATION12

LIST of FIGURES, TABLES and EQUATIONS
FIGURE 1. STILLING -WELL SUPPORTS.................................................................................................................... 3
FIGURE 2GK405 READOUT UNIT ............................................................................................................................ 6
FIGURE 3TYPICAL CALIBRATION SHEET................................................................................................................... 8
FIGURE 4. DENSITY P OF PURE WATER AS A FUNCTION OF TEMPERATURE AND PRESSURE INTENSITY.BY
PERMISSION FROM FLUID MECHANICS FOR HYDRAULIC ENGINEERS,BY HUNTER ROUSE,COPYRIGHT
1938, MCGRAW-HILL BOOK COMPANY,INC..................................................................................................10

1
Specifications
Model No.
4675LV
Range
mm1150, 300, 600, 1500
Accuracy2
±0.1% F.S.
Temperature Range
3-30°to +80°C
Frequency Range
1400-3500Hz
Materials:
Sensor and
weight:
Stilling Well:
Stainless steel
PVC standard, stainless steel
(optional)
Cable
4-Conductor, 22 gage PVC jacket
Sensor
Diameter - 1.00”
Length - 8.5”
1Other ranges available on request
2Accuracy achieved by using a polynomial expression rather than a linear coefficient
3Using anti-freeze solution can extend the range below 0°C. The system requires
calibration with the solution being used.

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1. Introduction______________________________________________________
The Geokon Model 4675LV Weir Monitor is designed for the measurement of water
levels in streams, weirs, flumes, etc., where accurate measurements of very small
water level changes are required. The unit consists of a vibrating wire from which is
suspended a hanging cylindrical weight partially submerged in the water. As the water
level rises and falls, the buoyancy forces acting on the weight change causing
changes in the tension and vibrational frequency in the vibrating wire. Level changes
of as little as .001” can be measured. Ranges of up to 10’ are available.
2. Installation Procedures _____________________________________________
2.1. Preliminary Checks
Before installing the weight cylinder, there is an orange colored spacer which
lies between the base of the sensor and the nut on the hook assembly, this
needs to be removed. (This releases the tension in the sensor wire –put there as a
safety precaution to protect the sensor from damage during shipment.)
The gage and weight assembly can now be checked out on site by connecting the
sensor to the readout system and measuring the output of the sensor with the weight
hanging from it in air. The readings [in Readout box channel “B”] should coincide
within about 200 digits of the factory reading in air shown on the calibration sheet. Be
sure that the sensor is held firmly and allow the system to stabilize (no swinging of the
weight). Detach the weight after this preliminary check. Always handle with great
care to prevent breakage.
2.2 Installation
If the 4675LV is used in a weir box, a stilling-well is required. The stilling-well is
provided by Geokon, in the form of a slotted, 3 inch or 4 inch PVC pipe. This stilling
well must be installed in a vertically plumb position in an area where there is little
turbulence and positioned in such a way that the bottom of the weight is slightly
lower than the tip of the V notch, It is important that the well be vertical, because
any friction from the weight rubbing along the well will influence the sensor output
The installation is made by using two pipe-straps to hold the stilling well in place. Two
spacer bars are provided to hold the stilling well away from the wall so that the stilling

3
well cap can be removed and replaced as necessary. For concrete weir boxes 4 Rawl
plugs are provided. Mark out the position for four bolt holes, (see Figure 1), and drill a
½ inch (12mm) diameter hole 2 inch (50mm) deep at each location. (The spacer bar
can be used to help locate the hole spacing properly). A 3/8 Rawl plug (four provided)
is installed in each hole, using the installation tool provided. The Rawl plug is first
placed in the hole and tapped flush with the surface. Then place the installation tool
inside the Rawl plug and set the anchor by means of several sharp hammer blows.
The PVC slotted tubing has a bottom plug at its lower end, which can now be
cemented in place using PVC cement. (It is left loose in case the PVC pipe needs to
be shortened a little due to space limitations). Use the four 3/8-16 bolts provided to
bolt the stilling well to the wall of the weir box using the pipe-strap and spacer bars.
Figure 1. Stilling -Well Supports.

4
Check that the sensor is reading then push it inside the Swagelok fitting in the pipe
cap and tighten the Swagelok one full turn after finger tight. Leave about one inch of
the sensor protruding from the Swagelok. Carefully attach the weight to the eyebolt on
the base of the sensor and lower the assembly into the stilling well until the pipe cap
sits firmly on top of the pipe.
The yellow vented readout cable can now be extended to a local readout location
where an optional terminal box can be used to enclose the end of the yellow vented
cable and the vent line moisture trap. If the readout location is remote from the weir
location then a blue un-vented cable can be used between the terminal box containing
the moisture trap and the readout location.
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, ie. inches or millimeters. Consult the GK-403
Instruction Manual for additional information on Mode "G" of the Readout. The
following instructions will explain taking gage measurements using Mode "B".
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 transducer, the white and
green clips are for the thermistor and the blue for the shield drain wire.
1. Turn on the Readout. Turn the display selector to position "B". Readout is in
digits.
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 its-self off after approximately 2 minutes to
conserve power.