YSI 3100 User manual

YSI Model 3100
Conductivity
Salinity
Temperature
Instrument
Operations
Manual
C
µS
CONDUCTIVITY INSTRUMENT

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Table of Contents
1. Introduction..............................................................................................................................................1
1.1 Capabilities ...................................................................................................................................................... 1
1.2 Controls............................................................................................................................................................ 2
Front Panel...................................................................................................................................................... 2
Rear Panel....................................................................................................................................................... 3
2. Getting Started.........................................................................................................................................4
2.1 Unpacking........................................................................................................................................................ 4
2.2 Warranty Card.................................................................................................................................................. 4
2.3 What You Need ............................................................................................................................................... 4
3. System Configuration and Operation....................................................................................................5
3.1 Turning the Instrument On............................................................................................................................... 5
3.2 Connect the Cell............................................................................................................................................... 5
3.3 Configure the 3100 .......................................................................................................................................... 6
Cell Constant .................................................................................................................................................. 6
3.4 Measurement Modes........................................................................................................................................ 7
3.5 Making Measurements..................................................................................................................................... 9
3.6 Autoranging & Range Searching ..................................................................................................................... 9
3.7 Platinization..................................................................................................................................................... 9
4. Advanced Setup.....................................................................................................................................10
4.1 Cell Calibration.............................................................................................................................................. 10
4.2 Temperature Coefficient................................................................................................................................ 12
4.3 Reference Temperature.................................................................................................................................. 12
4.4 Manual Ranging............................................................................................................................................. 13
5. Maintenance...........................................................................................................................................15
5.1 Cell Cleaning and Storage.............................................................................................................................. 15
5.2 Platinization................................................................................................................................................... 15
6. Troubleshooting....................................................................................................................................17
Error Messages ............................................................................................................................................. 17
7. Principles of Operation.........................................................................................................................19
7.1 3100 Principles .............................................................................................................................................. 19
7.2 Conductivity Principles.................................................................................................................................. 19
Introduction .................................................................................................................................................. 19
Conductivity Fundamentals .......................................................................................................................... 19
Cell Constant ................................................................................................................................................ 20
Choosing a Conductivity Cell....................................................................................................................... 21
Cell Constant Calculation ............................................................................................................................. 22
Conductivity Cell Calibration - Some Things To Remember ..................................................................... 22
Conductivity Law.......................................................................................................................................... 23
Low Conductivity Measurements ................................................................................................................. 23
General Conductivity Measurement Precautions.......................................................................................... 24
Platinization.................................................................................................................................................. 24
Temperature Correction................................................................................................................................ 24

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Small Sample Measurements........................................................................................................................ 25
Conductivity System Accuracy Considerations............................................................................................ 26
7.3 Salinity........................................................................................................................................................... 26
7.4 Temperature................................................................................................................................................... 27
7.5 Sources of Errors ........................................................................................................................................... 27
Cell Contamination....................................................................................................................................... 27
Cell Platinizing ............................................................................................................................................. 27
Electrical-Noise Errors ................................................................................................................................. 27
Contact Resistance........................................................................................................................................ 27
Cable Series Resistance and Shunt Capacitance........................................................................................... 28
Galvanic and Miscellaneous Effects............................................................................................................. 28
8. Warranty & Repair .................................................................................................................................29
8.1 Cleaning Instructions ..................................................................................................................................... 30
8.2 Packing Instructions....................................................................................................................................... 31
8.3 Disassembly/Assembly Procedures................................................................................................................ 32
9. Accessories and Replacement Parts...................................................................................................33
9.1 YSI Conductivity Cells.................................................................................................................................. 34
9.2 Standard Calibrator Solutions........................................................................................................................ 35
10. Required Notice...................................................................................................................................36
11. Appendix A - Specifications ...............................................................................................................37
12. Appendix B - Temperature Correction Data For Typical Solutions................................................38
13. Appendix C - Conversion Factors......................................................................................................42
14. Appendix D - Glossary of Terms........................................................................................................43

1
1. Introduction
The YSI Model 3100 is a microprocessor based instrument designed to perform laboratory
measurement of conductivity, salinity and temperature. The instrument’s push button operation
makes it simple to use.
The Model 3100's microprocessor allows the system to be easily calibrated with the press of a
few keys. Additionally, the microprocessor performs a self-diagnostic routine each time the
instrument is turned on. The self-diagnostic routine provides you with useful information about
the cell constant, function of the instrument circuitry, and the quality of the readings you obtain.
The system simultaneously displays temperature (in oC), along with one of the following
parameters: conductivity (in µS/cm or mS/cm), temperature compensated conductivity, (in
µS/cm or mS/cm), and salinity (in parts per thousand [ppt]). You can switch back and forth from
salinity, conductivity, and temperature compensated conductivity with a single push of the
[MODE] key.
The new YSI 3200 series conductivity cells contain internal temperature sensors for temperature
measurement and automatic temperature compensation. The Model 3100 is also compatible with
YSI 3400 series conductivity cells when used with the YSI Model 3232 cell adapter. However
3400 series cells do not contain an internal temperature sensor, therefore, when using a 3400
series cell, temperature measurement, temperature compensation or salinity measurement is not
possible.
1.1 Capabilities
•Adjustable reference temperature 15 to 25 °C
•Automatic temperature compensation
•Adjustable temperature compensation factor 0 to 4%/°C
•Adjustable Cell constant, ranges:
0.01, 0.08-0.12, 0.8-1.2, 8-12
•Auto or manual ranging
•Conductivity or Salinity readings
•7-pin mini DIN connector with thermistor connections
•AC line power

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1.2 Controls
Front Panel
The front panel of the instrument contains the display and keypad as shown below.
3100 CONDUCTIVITY INSTRUMENT
12.85uS
22.4°C
Power
ON/OFF
MODE Key
Dis
p
la
y
ENTER Ke
y
UP ARROW
DOWN ARROW

3
The following diagram shows the typical display.
10.00µS
24.8°C
The [Mode] key is used to select the current display mode. Mode choices are conductivity,
temperature compensated conductivity or salinity. Temperature is always displayed at the bottom
of the screen.
Rear Panel
The rear panel contains the connections for the power supply and cell. It also has a mounting post
for the 3232 adapter as shown below.
@ 100ma
Power Supply Connection
The power supply connection requires a 12 VDC power supply (included) with at least 100 ma
current. The polarity is marked on the instrument.
Conductivity:
mS/cm
uS/cm
Temperature compensated conductivity:
mS/cm
uS/cm
Salinity:
ppt
Temperature: °C
Adapter mounting post
NOTE: Flashing °C symbol
indicates temperature
compensation is enabled.

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Cell Connection
The connector for the cell is a 7-pin mini DIN connector and is marked with an arrow to show
proper alignment. Be sure to align the arrows when plugging in the cell.
YSI 3200 series cells utilize a mini DIN connector that plugs directly into the 3100. If, however,
you have a YSI 3400 series cell, the YSI 3232 cell adapter will be required. The YSI 3232
adapter mounts on the post on the rear of the 3100. It has a 7-pin mini-DIN connector and two
binding posts. The mini-DIN connector plugs into the 3100 cell socket and a YSI 3400 series cell
(or equivalent) connects to the binding posts.
YSI 3200 series cells contain an internal temperature sensor for temperature measurement,
temperature compensation and salinity. YSI 3400 series cells do not contain an internal
temperature sensor, therefore, when using a 3400 series cell, temperature measurement,
temperature compensation or salinity measurement is not possible.
2. Getting Started
2.1 Unpacking
When you unpack your new YSI Model 3100 for the first time, check the packing list to make
sure you have received everything you should have. If there is anything missing or damaged, call
the dealer from whom you purchased the Model 3100. If you do not know which of our
authorized dealers sold the system to you, call YSI Customer Service at 800-765-4974 or 937-
767-7241, and we'll be happy to help you.
2.2 Warranty Card
Please complete the Warranty Card and return it to YSI. This will record your purchase of this
instrument in our computer system. Once your purchase is recorded, you will receive prompt,
efficient service in the event any part of your YSI Model 3100 should ever need repair.
2.3 What You Need
Several things are needed in order to make accurate conductivity measurements using the YSI
3100. The following list shows the basic items required.
•Instrument
•Power Supply
•Conductivity Cell
•Standard Solution(s)
•Beakers
•Rinsing Solution

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3. System Configuration and Operation
3.1 Turning the Instrument On
Plug the power supply into its mating connector on the back of the instrument. Depress
the (on/off) key to turn the instrument on. The instrument will activate all segments of the
display for a few seconds, which will be followed by a self test procedure which will last for
several more seconds. During this power on self test sequence, the instrument’s microprocessor
is verifying that the instrument is working properly. The Model 3100 will display the current cell
constant when the self test is complete.
1.00
CEL
If the instrument detected a problem, the display will show a continuous error message. For a list
of these error messages, see chapter 6 Troubleshooting. After the instrument completes this
diagnostic routine, the following screen should be displayed (with no cell connected).
0.00µS
udr°C
3.2 Connect the Cell
Plug the cell (YSI 3200 series) into the connector on the back of the instrument marked cell. YSI
3200 series cells contain an internal temperature sensor for temperature measurement and
compensation.
If you are using a YSI 3400 series cell, you will need the YSI 3232 cell adapter. YSI 3400 series
cells do not contain an internal temperature sensor, therefore, when using a 3400 series cell,
temperature measurement, temperature compensation or salinity measurement is not
possible.
Cell constant

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16.34µS
24.8 °C
3.3 Configure the 3100
Before operating the 3100, or whenever you change cells, you must configure the 3100 to match
the cell used. You must enter the manufacturer’s stated (or your manually calculated) cell
constant (K) as shown below (Cell Constant).
The default configuration is as follows:
•Cell constant of K = 1
•Temperature compensation corrected to 25°C using a coefficient of 1.91%/°C.
If you are using a cell with a cell constant of K=1 (such as the YSI 3252, 3253, 3254, 3401,
3403, 3417, or 3445), the cell constant is already set correctly. If, however, you are using a cell
with a different cell constant (such as the YSI 3256, 3255, 3402, 3418, 3440, or 3446), you must
enter the manufacturer’s stated cell constant for the cell that you are using (K= 0.1, 10.0 etc.) as
shown below (Cell Constant).
Cell Constant
Follow these steps to change the cell constant.
1. With the instrument on, press and release the [DOWN ARROW] and [MODE] keys at the
same time. The CAL symbol will appear at the bottom left of the display and the large portion
of the display will show 1.91%(or a value set previously using Advanced Setup).
1.91%
22.7 °C
CAL
2. Press and release the [MODE] key. The large portion of the display will show 25.0C (or a
value set previously using Advanced Setup).
3. Press and release the [MODE] key again. The large portion of the display will show 1.00 (or a
value set previously using Advanced Setup).
Temperature: °C
Conductivity
Cal symbol

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1.00
CAL
4. Use the [UP ARROW] or [DOWN ARROW] keys to change the value to the desired new cell
constant.
0.10
CAL
5. Press the [ENTER] key. The word “SAVE” will flash across the display for a second to
indicate that your change has been accepted. The 3100 will return to normal operation mode.
SAVE
3.4 Measurement Modes
The Model 3100 is designed to provide four distinct measurements:
!Conductivity -- A measurement of the conductive material in the liquid sample without regard
to temperature
!Temperature Compensated Conductivity -- Automatically adjusts the reading to a calculated
value which would have been read if the sample had been at 25oC (or some
other reference temperature which you choose). See section 4. Advanced
Setup. NOTE: Requires YSI 3200 series cell.
!Salinity -- A calculation done by the instrument electronics, based upon the conductivity and
temperature readings. NOTE: Requires YSI 3200 series cell.
!Temperature -- Always displayed.
NOTE: When you turn the Model 3100 off, it will “remember” which mode you used last and
will return to that mode the next time the instrument is turned on.
Cell constant
New cell constant

8
To choose one of the measurement modes (temperature is always displayed), simply press and
release the [MODE] key. Carefully observe the small legends at the far right side of the LCD.
Conductuctivity
with °C
Temperature
Compensated
Conductivity
with °C
Salinity
with °C
If the instrument is reading Temperature compensated conductivity, the large numbers on the
display will be followed by either a µS or mS and the small portion of the display will show the
oC flashing on and off.
If the instrument is reading Conductivity, the large numbers on the display will be followed by
either a µ
µµ
µSor mS, but the small portion of the display will show the oC NOT flashing.
10.62mS
24.8 °C
NOTE: The instrument measures conductivity in uS/cm or mS/cm even though the /cm is
not shown on the display.
If the instrument is reading Salinity, the large numbers on the display will be followed by a ppt.
34.2ppt
24.8 °C
NOTE: Temperature compensated conductivity and salinity modes cannot be used unless a
YSI 3200 series cell is connected. When using a YSI 3400 series cell (or equivalent)
with the 3232 cell adapter, these modes will display an error message (“LErr”) since
3400 series cells do not contain a temperature sensor.
°C Not flashing = Conductivity
°C Flashing = Temperature compensated
conductivity
Salinity

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3.5 Making Measurements
After setting up the 3100 instrument and cell as described earlier, the following basic steps
should be used to make measurements.
1. Verify that the 3100 is properly set up to use the current cell by measuring, or calibrating
with, a standard conductivity solution. See section 4.1 Cell Calibration.
2. Immerse the cell in the solution to be measured.
3. Gently tap the cell to remove any air bubbles and dip the cell in the solution 2 or 3 times
to ensure proper wetting. The cell electrodes must be submerged and the electrode
chamber must not contain any trapped air. If using a flow through or fill cell, be certain it
is completely full.
4. Allow time for the temperature to stabilize.
5. Press the [MODE] key to select the units required, then read the display.
6. Rinse the cell with distilled or deionized water.
3.6 Autoranging & Range Searching
The YSI Model 3100 is an autoranging instrument. This means that, regardless of the
conductivity or salinity of the solution (within the specifications of the instrument), all you need
to do to get the most accurate reading is to put the cell in the sample. This feature makes the
Model 3100 as simple as possible to operate.
When you first place the cell into a sample or calibration solution, and again when you first
remove the cell, the instrument will go into a range search mode that may take as long as 5
seconds. During some range searches, the instrument display will flash rANG to indicate its
movement from one range to another.
rANG
The length of the range search depends on the number of ranges which must be searched in order
to find the correct range for the sample. During the range search, the instrument will appear to
freeze on a given reading for a few seconds then, once the range is located, will pinpoint the
exact reading on the display. The display may also switch to 00.0 for a second or two during a
range search before it selects the proper range.
During normal operation, the [ENTER] key enables and disables the autoranging feature of the
instrument. See 4.4 Manual Ranging if you need to switch to manual ranging.
3.7 Platinization
The 3100 can be used to replatinize the electrodes of the cell. See section 5.2 Platinization for
details.

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4. Advanced Setup
For highest accuracy, the 3100 and cell may be calibrated as a system using standard conductivity
calibration solutions. See the following section, 4.1 Cell Calibration, for details.
The default temperature compensation settings of the YSI Model 3100 are appropriate for the
vast majority of measurement applications. However, some measurement applications require
very specific measurement criteria. For that reason, we have made the YSI Model 3100 flexible
to accommodate these “advanced users.”
If, for example, you are using the YSI Model 3100 for a process control application which
requires that the conductivity readings be compensated to 20°C instead of 25°C -- see section,
4.3 Reference Temperature. Or, if your application involves the measurement of a very specific
saline solution, the default temperature coefficient may need to be changed to get the very best
measurement of that specific salt. See section 4.2 Temperature Coefficient.
4.1 Cell Calibration
Prior to calibration of the YSI Model 3100, it is important to remember the following:
•The cell constant must be set correctly before calibrating. See section 3.3 Configure the 3100,
Cell Constant.
•Always use clean, properly stored, NIST traceable calibration solutions (see section 9.2
Standard Calibrator Solutions). When filling a calibration container prior to performing the
calibration procedures, make certain that the level of calibrant buffers is high enough in the
container to cover the electrodes. Gently agitate the cell to remove any bubbles in the
conductivity cell.
•Rinse the cell with distilled water (and wipe dry) between changes of calibration solutions.
•During calibration, allow the cell time to stabilize with regard to temperature (approximately
60 seconds) before proceeding with the calibration process. The readings after calibration are
only as good as the calibration itself.
•Perform calibration at a temperature as close to 25°C as possible. This will minimize any
temperature compensation error.
Follow these steps to perform an accurate calibration of the YSI Model 3100:
1. Select a calibration solution which is most similar to the sample you will be measuring.
•For sea water choose a 50mS/cm conductivity standard (YSI 3165 or 3169)
•For fresh water choose a 1mS/cm conductivity standard (YSI 3161 or 3167)
•For brackish water choose a 10mS/cm conductivity standard (YSI 3163 or 3168)
2. Place at least 3 inches of solution in a clean glass beaker.
3. Insert the cell into the beaker deep enough to completely cover the electrodes. Do not rest the
cell on the bottom of the container -- suspend it above the bottom at least 1/4 inch.

11
4. Gently tap the cell to remove any air bubbles and dip the cell in the solution 2 or 3 times to
ensure proper wetting. If using a flow through or fill cell, be certain it is completely full.
5. Allow at least 60 seconds for the temperature reading to become stable.
6. Press the [MODE] key until the instrument is in the conductivity mode that you want to
calibrate in as follows:
Temperature compensated conductivity (°C symbol flashing): This mode will
automatically compensate the calibration value to
25°C using a coefficient of 1.91%/°C.
Conductivity (°C symbol NOT flashing): This mode does NOT use temperature
compensation.
7. Press and release both the [UP ARROW] and [DOWN ARROW] keys at the same time.
10.12mS
24.3 °C
CAL
The CAL symbol will appear at the bottom left of the display to indicate that the instrument is now
in Calibration mode.
8. Use the [UP ARROW] or [DOWN ARROW] key to adjust the reading on the display until
it matches the value of the calibration solution you are using. If you are calibrating in
temperature compensated conductivity mode, enter the value at 25°C. If you are calibrating in
conductivity mode (not temperature compensated), enter the value the calibration solution
should read at the current temperature (see Appendix B).
10.00mS
24.3 °C
CAL
9. Once the display reads the exact value of the calibration solution being used, press the
[ENTER] key. The word “SAVE” will flash across the display for a second indicating that
the calibration has been accepted.
The YSI Model 3100 is designed to retain its last calibration permanently. Therefore, there is no
need to calibrate the instrument after power down.
CAL symbol
Calibration solution value

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4.2 Temperature Coefficient
Follow these steps to modify the temperature coefficient of the Model 3100.
1. Press and release the [DOWN ARROW] and [MODE] keys at the same time. The CAL
symbol will appear at the bottom left of the display and the large portion of the display will
show 1.91%(or a value set previously using Advanced Setup).
1.91%
22.7 °C
CAL
2. Use the [UP ARROW] or [DOWN ARROW] key to change the value to the desired new
temperature coefficient.
1.50%
22.7 °C
CAL
3. Press the [ENTER] key. The word “SAVE” will flash across the display for a second to
indicate that your change has been accepted.
4. Press the [MODE] key two times to return to normal operation; the CAL symbol will
disappear from the display.
See Appendix B for charts of common salt solutions at various temperatures.
4.3 Reference Temperature
Follow these steps to modify the reference temperature of the Model 3100.
1. Press and release the [DOWN ARROW] and [MODE] keys at the same time.
1.91%
22.7 °C
CAL
Temperature coefficient
CAL symbol
CAL symbol
New temperature coefficient

13
The CAL symbol will appear at the bottom left of the display and the large portion of the
display will show 1.91%(or a value set previously using Advanced Setup).
2. Press and release the [MODE] key. The large portion of the display will show 25.0C (or a
value set previously using Advanced Setup).
25.0C
22.7
CAL
3. Use the [UP ARROW] or [DOWN ARROW] key to change the value to the desired new
reference temperature (the allowable range is 15°C to 25°C).
15.0C
22.7
CAL
4. Press the [ENTER] key. The word “SAVE” will flash on the display for a second to indicate
that your change has been accepted.
5. Press the [MODE] key to return to normal operation.
4.4 Manual Ranging
If your application is easier to perform using a manual range that you select, the YSI Model 3100
allows you to turn off the default autoranging feature. While you are making conductivity or
temperature compensated conductivity measurements, simply press and release the [ENTER]
key. The conductivity units will flash indicating that the instrument is now in a manual range.
Each additional press of the [ENTER] key will cycle the Model 3100 to a different manual range
until you return again to autoranging. Six pushes of the [ENTER] key will cycle the Model 3100
through the five available manual ranges and return the instrument to autoranging.
10.62mS
24.8 °C
Reference temperature
New reference tem
p
erature
Flashes to indicate
Manual range

14
NOTE: You may see an error message in some manual ranges if the range selected is not
adequate for the sample you are measuring.
rErrmS
24.8 °C
If this happens, simply press and release the [ENTER] key again until a range is selected which
is suitable for your sample. If you get lost and don’t know if you’re in a manual range or
autoranging, simply turn the instrument off and back on. The instrument will default to
autoranging when first turned on.
The YSI Model 3100 has five possible ranges. The number of ranges available for use depends
on the current cell constant.
Cell
Constant Range 1
0 - 49.99 µS/cm Range 2 0 - 499.9 µS/cm Range 3 0 - 4999 µS/cm Range 4
0 - 49.99 mS/cm Range 5 0 - 499.9 mS/cm
K=0.01 √√
K=0.1 √√√
K=1 √√√√
K=10 √√√ √
NOTE: Cells may be used beyond their normal range, but with instability and/or reduced
accuracy.
Range error message

15
5. Maintenance
5.1 Cell Cleaning and Storage
The single most important requirement for accurate and reproducible results in conductivity
measurement is a clean cell. A dirty cell will change the conductivity of a solution by
contaminating it.
To clean a conductivity cell:
1. Dip or fill the cell with cleaning solution and agitate for two to three minutes. Any one of
the foaming acid tile cleaners, such as Dow Chemical Bathroom Cleaner, will clean the
cell adequately. When a stronger cleaning preparation is required, use a solution of 1:1
isopropyl alcohol and 10N HCl or Sulfuric Acid or Ethanol or Methanol.
CAUTION: Cells should not be cleaned in aqua regia or in any solution known to etch
platinum or gold.
2. Remove the cell from the solution and rinse in several changes of distilled or deionized
water. Inspect the platinum black to see if replatinizing is required.
Storage
Short term: Store conductivity cells in deionized or distilled water. Change the water frequently
to prevent any growth that may cause electrode fouling.
Long term: Rinse thoroughly with deionized or distilled water and store dry. Any cell that has
been stored dry should be soaked in distilled water until the electrodes appear black
before use.
5.2 Platinization
The electrodes of YSI 3200 and 3400 Series conductivity cells are coated with platinum black
during manufacturing. This coating is extremely important to cell operation, especially in
solutions of high conductivity.
The cell should be inspected periodically. If the coating appears to be thin or if it is flaking off,
the electrodes should be cleaned, as noted above, and replatinized. Properly maintained
conductivity cells will perform for years without replatinizing.
The 3100 can be used to replatinize the electrodes of the cell. In addition, you will need a 2-oz
bottle of platinizing solution (YSI 3140).
WARNING: Before replatinizing the electrodes of a cell, make sure that the cell is
designed to have a platinum coating on the electrodes.
1. Immerse the cell in the platinizing solution (YSI 3140). Make sure that both electrodes are
submerged.

16
2. Press both the [UP ARROW] and [MODE] keys at the same time. The large portion of the
display will show “PLA” flashing, indicating that platinization is in process.
PLA
3. After the platinization process is complete (about 30 minutes), the 3100 will return to normal
mode. Remove the cell from the platinizing solution. If you want to stop the platinization
before 30 minutes have passed, press both the [UP ARROW] and [MODE] keys at the same
time to abort.
4. Thoroughly rinse the cell with distilled or deionized water.
5. Promptly return the platinizing solution to its container.