Geokon 3810 User manual

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 ©, 2009-2016 by Geokon, Inc.
(Doc Rev E, 04/07/17)
Installation Manual
Model 3800/3810
Thermistors & Thermistor Strings

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. 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
CONTENTS.......................................................................................................................................................1
1. INTRODUCTION.......................................................................................................................................1
2. INSTALLATION........................................................................................................................................1
3. READOUT.................................................................................................................................................1
4. DATALOGGER CONNECTION...............................................................................................................1
FIGUREA‐1:THERMISTORBRIDGEWIRING......................................................................................................2
TABLEB‐1:STANDARDTHERMISTORRESISTANCEVERSUSTEMPERATURE.......................................................4
TABLEB‐2:HIGHTEMPERATURETHERMISTORRESISTANCEVERSUSTEMPERATURE.........................................6

1
1. Introduction ______________________________________________________________
Thermistors are semiconductors, which behave as thermal resistors – that is, resistors with a
high (usually negative) temperature coefficient of resistance. The thermistor beads are made
from a mixture of metal oxides encased in epoxy or glass. The beads are small in size and
extremely robust with a high degree of stability over a long life span. Because their resistance
change is so great, it is unusual for cable effects to be significant. However, for high accuracy
work the cable resistance can be taken into account. Accuracies of the types of thermistor
beads used here is, +/- 0.5°C, (Model 3800-1-1-1), or +/- 0. 2°C( Model 3800-1-2-1). Standard
temperature ranges are -50 to 150 degrees C . High temperature versions are -30 to 230
degrees C.
2. Installation _______________________________________________________________
Model 3800-1-1, and Model 3800-1-2 thermistors are supplied inside a housing already potted
on the end of a cable ready to be attached to a structure or buried in the ground or in concrete.
The potting chamber is made from PVC for low temperature models or from stainless steel for
the high temperature models. Model 3810 Thermistor strings are made by removing a short
length of the outer jacket of a multi-pair conductor cable, at pre-determined depths; splicing a
Model 3800-1-1-1 into one of the pairs of conductors, then waterproofing the splice. Before
Installation read and record all the thermistors to check that they are functional and to establish
ambient temperature readings. Read and record once again as soon as the thermistor string has
been deployed and again after a certain length of time has elapsed to allow the temperatures
stabilize so as to establish good base line temperature readings.
3. Readout_________________________________________________________________
Thermistors can read using either a GK 403 or GK 404 readout box, which display the
temperature directly in degrees Celsius. Alternatively, for standard thermistors, rated at –50 to
+150 degrees Celsius a digital ohmmeter can be used in conjunction with the Table B1 shown
on the next page. High temperature thermistors can be read in a similar manner using Table B2
Note that if long cables are use it may be necessary to correct for the cable resistance. Standard
cable is 22 AWG with a resistance of 16 ohms per 1000ft. Remember, when calculating the
cable effect to count the distance there and back.
4. Datalogger Connection _____________________________________________________
A Multiplexer (Model 8032) is required to connect the Model 3810 Thermistor string to a
Datalogger (Model 8021/8025). The Common connection of the Thermistor String limits the
ability to connect the string directly to a Datalogger. A jumper is required on each channel of the
Multiplexer in order to split the Common between all of the Thermistors in the string.

2
-CR1000/CR800 Wiring for Model 8032 reading Thermistor String in 32ch mode
CR1000/CR800 Datalogger 8032 Multiplexer Description
12V 12V 12VDC Output
G G Power Ground
C# RES Control Port # / Reset
C# CLK Digital I/O Port # / Clock
AG AG Analog Ground
*SE# 1H Single Ended CH# input
for Thermistor
*VX# 1L Excitation VX#
* NOTE: The Thermistors are read using a Single Ended Channel and Excited with one of
the dataloggers excitation channels through a bridge completion circuit.
Figure A-1: Thermistor Bridge Wiring

3
NOTE: The DIP Switches for the 8032 Multiplexer should be set for 32 Channel mode.
Each individual Thermistor is connected (with common jumper) as shown below.
Multiplexer Wiring:
8032 Multiplexer Model 3800/3810
IH Thermistor Gage 1
1L Thermistor Common *
2H Thermistor Gage 2
2L Thermistor Common *
S Shield
3H Thermistor Gage 3
3L Thermistor Common *
NOTE: * Jumper required

4
Standard Temperature Thermistor Linearization using SteinHart-Hart Log Equation
Thermistor Type: YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3
Resistance to Temperature Equation: 2.273
)()( 13 
LnRCLnRBA T
Equation B-1: Convert Thermistor Resistance to Temperature
Where: TTemperature in C
LnR Natural Log of Thermistor Resistance
A1.4051 10-3 (coefficients calculated over the 50 to +150C span)
B2.369 10-4
C1.019 10-7
Ohms Temp Ohms Temp Ohms Temp Ohms Temp Ohms Temp
201.1
K
-50 16.60
K
-10 2417

30 525.4

70 153.2

110
187.3K -49 15.72K -9 2317 31 507.8 71 149.0 111
174.5
K
-48 14.90
K
-8 2221 32 490.9 72 145.0 112
162.7
K
-47 14.12
K
-7 2130 33 474.7 73 141.1 113
151.7K -46 13.39K -6 2042 34 459.0 74 137.2 114
141.6
K
-45 12.70
K
-5 1959 35 444.0 75 133.6 115
132.2
K
-44 12.05
K
-4 1880 36 429.5 76 130.0 116
123.5K -43 11.44K -3 1805 37 415.6 77 126.5 117
115.4
K
-42 10.86
K
-2 1733 38 402.2 78 123.2 118
107.9
K
-41 10.31
K
-1 1664 39 389.3 79 119.9 119
101.0K -40 9796 0 1598 40 376.9 80 116.8 120
94.48
K
-39 9310 1 1535 41 364.9 81 113.8 121
88.46
K
-38 8851 2 1475 42 353.4 82 110.8 122
82.87K -37 8417 3 1418 43 342.2 83 107.9 123
77.66
K
-36 8006 4 1363 44 331.5 84 105.2 124
72.81
K
-35 7618 5 1310 45 321.2 85 102.5 125
68.30K -34 7252 6 1260 46 311.3 86 99.9 126
64.09
K
-33 6905 7 1212 47 301.7 87 97.3 127
60.17
K
-32 6576 8 1167 48 292.4 88 94.9 128
56.51K -31 6265 9 1123 49 283.5 89 92.5 129
53.10
K
-30 5971 10 1081 50 274.9 90 90.2 130
49.91
K
-29 5692 11 1040 51 266.6 91 87.9 131
46.94K -28 5427 12 1002 52 258.6 92 85.7 132
44.16
K
-27 5177 13 965.0 53 250.9 93 83.6 133
41.56
K
-26 4939 14 929.6 54 243.4 94 81.6 134
39.13K -25 4714 15 895.8 55 236.2 95 79.6 135
36.86
K
-24 4500 16 863.3 56 229.3 96 77.6 136
34.73
K
-23 4297 17 832.2 57 222.6 97 75.8 137
32.74K -22 4105 18 802.3 58 216.1 98 73.9 138
30.87
K
-21 3922 19 773.7 59 209.8 99 72.2 139
29.13
K
-20 3748 20 746.3 60 203.8 100 70.4 140
27.49K -19 3583 21 719.9 61 197.9 101 68.8 141
25.95
K
-18 3426 22 694.7 62 192.2 102 67.1 142
24.51
K
-17 3277 23 670.4 63 186.8 103 65.5 143
23.16K -16 3135 24 647.1 64 181.5 104 64.0 144
21.89
K
-15 3000 25 624.7 65 176.4 105 62.5 145
20.70
K
-14 2872 26 603.3 66 171.4 106 61.1 146
19.58K -13 2750 27 582.6 67 166.7 107 59.6 147
18.52
K
-12 2633 28 562.8 68 162.0 108 58.3 148
17.53
K
-11 2523 29 543.7 69 157.6 109 56.8 149
55.6 150
Table B-1: Standard Thermistor Resistance versus Temperature