LaMotte DO 6 PLUS User manual

1
Code 5-0107-01
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

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PREFACE
This manual serves to explain the use of the DO 6 PLUS hand held
meter.
This manual functions in two ways: f rst as a step by step guide to
operating the meter; second, as a handy reference guide.
This manual is written to cover as many anticipated applications of the
DO 6 PLUS meter as possible. If there are questions about the use of this
meter contact the LaMotte Tech Service Department.
LaMotte Company will not accept any responsibility for damage or
malfunction to the meter caused by improper use of the instrument.
The information presented in this manual is subject to change without
notice as improvements are made, and does not represent a commitment
on the part of LaMotte Company.
WARNING! This set contains chemicals that
may be harmful if misused. Read cautions on
individual containers carefully. Not to be used by
children except under adult supervision.

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TABLE OF CONTENTS
1. INTRODUCTION 5
2. GETTING STARTED 6
2.1 Description of Keypad Functions 6
2.2 Description of LCD Annunciators 7
2.3 Inserting & removing the Rubber Boot/Stand 7
2.4 Inserting New Batteries 8
2.5 Battery Replacement 8
2.6 Connecting the Probe 9
2.7 Electrode Information 10
2.8 Switching the Meter On 11
2.9 Changing Mode 11
3. CALIBRATION 12
3.1 General Information 12
3.2 Temperature Calibration 13
3.3 % Saturation Calibration 14
3.3.1 100% Calibration 14
3.3.2 0% Calibration 15
3.4 mg/L or ppm Calibration 16
4. MEASUREMENT 17
4.1 Temperature Compensation 17
4.2 Taking Measurements 18
4.3 Pressure & Salinity Compensated Measurements 18
4.4 Holding a Reading 19
5. SETUP 19
5.1 Conf guration Menu (COF.1) 23
5.2 Automatic Temperature Compensation (A.ATC) 23
5.3 Selection of mg/L or ppm (b.DO) 24
5.4 Calibration Data (CAL.2) 24
5.5 Electrode Data (ELE.3) 25
5.6 Automatic Shut Off (AtO.4) 26
5.7 Reset to Factory Default (rSt.5) 26
5.8 % Saturation Offset Adjustment (OFS.6) 27
5.9 Pressure & Salinity Adjustment 29
6. PROBE MAINTENANCE 30
6.1 Cap and Electrolyte Replacement 31
6.2 Electrolyte Solution 32
7. TROUBLESHOOTING 32
8. ERROR MESSAGES 33
9. FACTORY DEFAULT SETTINGS 34
10. SPECIFICATIONS 35

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11. REPLACEMENT PARTS AND ACCESSORIES 36
12. DISSOLVED OXYGEN THEORY 37
Measurement Units 37
What Is Being Measured? 37
Air Calibration 38
Applications 38
13. WARRANTY 39
14. REPAIRS 40

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1. INTRODUCTION
The DO 6 PLUS microprocessor-based handheld meter is economical
and easy to use. It has a large custom LCD (Liquid Crystal Display) for
clear and easy reading.
The DO 6 PLUS offers measurement of dissolved oxygen (DO) as
percentage saturation or concentration. Temperature measurement is
available in degrees Celsius. The meter ensures accurate measurement
of the dissolved oxygen values through the temperature, barometric
pressure and salinity compensation features.
Meter kits include a dissolved oxygen probe, ref ll solution, a rubber
boot/stand, 4 alkaline “AAA” batteries and instruction manual. For
additional information, see Section 11 — Replacement Parts and
Accessories.
Read this manual thoroughly before operating the meter.

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2. GETTING STARTED
2.1 Description of Keypad Functions
The meter has 6 keys on a splash-proof keypad. Some buttons have
multiple functions depending on the mode of operation.
ON/OFF Powers meter on and off. Meter starts up in the
measurement mode that was last used.
CAL Enters into calibration mode. Pressing while in calibration
mode will abort calibration without conf rming value.
MODE Selects desired measurement mode. When pressed
simultaneously with ON/OFF, it will go to the SETUP
mode.
HOLD Freezes measured reading. Press again to resume live
reading.
ENTER Conf rms calibration value in calibration mode and
conf rm selections in SETUP mode.
Increments/decrements values during calibration mode or
scroll through SETUP menus. Set offset adjustments and
conf guration settings.

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2.2 Description of LCD Annunciators
The meter has a large custom LCD that consists of 4-digit segments plus
annunciators for percentage saturation (%), concentration (mg/L or ppm)
and Temperature in degrees Celsius (T).
Other annunciators include “A” (when the ATC function is activated),
“CAL” (when meter is in calibration mode) and low battery condition.
milligram per litre
(Concentration Mode)
mg/l
ppm
%
TA
14-segment Liquid Crystal Display
Low Battery annunciator
Calibration Mode
Annunciator
CAL
Temperature Mode
A T C annunciator
parts per million
Percentage
(Percentage Saturation
Mode)
2.3 Inserting & Removing the Rubber Boot/Stand
1. To remove the meter from the rubber boot, push out the bottom
edge of the meter until it is completely out of the boot. Ensure
that the probe cables are not connected. See Figure 1.
2. To insert the meter into the rubber boot, slide in the top of the
meter before pushing the bottom edge of the meter down to set it
into position. Lift up the stand at the back of the meter for bench
top applications. See Figure 2.
Figure 1 Figure 2

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2.4 Inserting New Batteries
The battery compartment is found at the back of the instrument. To open
the battery compartment, push the cover in the direction of the arrow and
lift up. Note the polarity of batteries before inserting them into position.
After the batteries have been replaced, reposition the cover and press
down until it locks.
2.5 Battery Replacement
A low battery annunciator on the LCD alerts when the battery power is
running low. Caution: Power off the meter before replacing the batteries.
%
Low Battery Condition

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2.6 Connecting the Probe
1. To connect the probe, align the connector slots with the posts of
the meter socket and rotate the connector clockwise until it locks.
2. To remove the probe, rotate the connector in an anti-clockwise
direction until it unlocks, and slide the connector off the socket.
3. Insert the mini phono jack of the temperature sensor into the
socket on the meter as shown below.
2.5 mm mini phono
jack for
temperature sensor
BNC connector
for DO probe

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2.7 Electrode Information
The DO 6 PLUS includes a galvanic DO electrode
which does not require warm-up. It generates
a millivolt signal proportional to the amount of
oxygen in the solution.
The probe has a dual cable; a BNC connector
for DO measurement and a phono jack plug
for temperature. The sensor utilizes a cathode,
anode, and electrolyte that are separated from
the sample by an oxygen permeable membrane.
The membrane is pre-assembled and f xed to a
detachable cap. The pre-assembled cap design
allows simple replacement and fast conditioning.
The probe is lightweight and includes a built-in
temperature sensor. The epoxy body of the probe
is 12mm in diameter while the detachable Noryl
cap is 16mm in diameter. The compact sensing
area reduces air entrapment resulting in quick,
accurate, and stable readings.
The pre-assembled cap must be completely
submersed in the solution to obtain an accurate
reading. Provide simple stirring for best results—
ideally achieve a minimum water f ow rate of 2 inch/second on the
membrane. The probe is not recommended for use in samples outside of
the range of 0 to 50 °C.
Shaking the probe will aid in removing bubbles, if needed, before taking
a reading. When calibrating in air, shake to remove water from the
membrane.
The membrane is thin and can not be repaired if it is damaged. Use care
to protect from scratches, abrasions, or contact with solids. For best
results keep the membrane clean by rinsing it after daily use. See Section
6 – Probe Maintenance.
Detachable
Pre-membraned Cap
(Probe Sensing Area)
16 mm
12 mm

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2.8 Switching the Meter On
Press ON/OFF to power up the meter. The meter will
cycle through various setup parameters.
1. All LCD segments will brief y illuminate.
2. The model name [DO 6] will display next along
with mg/l, ppm, and % annunciators.
3. Next, the meter revision number [r #.##] is
shown brief y before beginning measurement.
4. The meter will be in the measurement mode
that was in use when it was powered off—%,
mg/l, ppm, or T.
2.9 Changing the Mode
Press MODE to switch between percentage saturation (%), concentration
(mg/L)(ppm), and temperature (T) measurement.
mg/l
A
TA
A
%
MODE
MODE
MODE
Percentage Saturation
Concentration Mode
Temperature Mode
Automatic Temperature
Compensation
CAL 13 CAL 24
mg/l
NTU
ppm
%pH
TAvg
mg/l
ppm
%
ON
OFF
A
%

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3. CALIBRATION
3.1 General Information
The DO 6 PLUS has three measurement modes; DO as % saturation, DO
as mg/L (or ppm) concentration, and temperature.
Dissolved oxygen levels vary with temperature, barometric pressure, and
salinity, so the calibration must be performed with consideration of these
factors. It is necessary to set the proper temperature, barometric
pressure and salinity values prior to performing any DO calibration
or measurement.
See Section 3.2 — Temperature Calibration
See Section 5.2 — Automatic Temperature Compensation
See Section 5.9 — Pressure & Salinity Adjustment
The DO 6 PLUS will accept two % saturation calibration points; 100%
using saturated air or air-saturated water, and 0% using a zero oxygen
solution. When the 100% calibration is performed, the corresponding
concentration is adjusted simultaneously. Therefore, it is not necessary
to calibrate the concentration mode. If calibrating for 0% oxygen, note
that the meter will take several minutes to reach 0% saturation value and
constant stirring is not required.
The following table lists calibration values in % saturation calibration
mode with two different barometric pressures. Note that the saturation
value (92.1%) has decreased due to the lower barometric pressure
entered.
% Saturation (per
factory default value)
Calibration Value
(760mmHg)
Calibration Value
(700mmHg)
less than 10% 0% 0%
10.1% to 49.9% Err.1 (error 1) Err.1 (error 1)
50% to 200% 100% 92.1%
If calibration is attempted from 10.1% to 49.9%, the “Err.1” message will
be shown. The calibration will be rejected and the display will return to
the measurement mode.
The DO 6 PLUS will accept one calibration point in concentration mode.
The minimum value is 2 mg/L (ppm), and the calibration window is
±40% of the factory default value.
Temperature and % saturation calibration should take place before
attempting to perform mg/L (ppm) concentration calibration.
Calibration of the concentration mode will only replace the previous
concentration calibration and does not affect the % saturation calibration.

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To offset the % saturation reading to match another instrument, see
Section 5.8 — % Saturation Offset Adjustment.
New calibration values will automatically override the existing data.
Perform a daily calibration for best results. To completely recalibrate
the meter and when installing a replacement probe, it is best to clear all
calibration data prior to performing the calibration. See Section 5.7 Reset
to Factory Default.
3.2 Temperature Calibration
For the most accurate DO readings, ensure that the temperature is
accurate. The temperature sensor of the DO 6 PLUS probe has been
factory calibrated, however if it changes over time, or if the probe
is replaced, calibration may be necessary. To protect from erroneous
calibrations, the allowable tolerance is limited to ±5°C adjustment of the
factory default value.
Most users utilize the automatic temperature compensation feature that
uses the sensor that is built into the probe. However, manual temperature
compensation can be used to input a f xed, known temperature.
1. Press MODE to select the temperature
mode. The display will show “T” for
temperature and “A” for automatic
temperature compensation.
2. Dip the probe into a solution with a
known, accurate temperature (i.e. a
temperature bath). Allow enough time
for the temperature reading to stabilize.
3. Press CAL. The CAL indicator
will blink above the display. The
temperature value shown is the value
based on the factory default.
4. Press or to adjust the reading
to match the correct temperature value
(i.e. of the temperature bath).
5. Press HOLD/ENTER to conf rm
the calibration and return to the
measurement mode.
Press CAL as needed to exit calibration without
conf rmation at any time.
CAL
CAL
T
T
A
A
TA
TA
CAL
HOLD
ENTER
Factory default
Temperature
Measurement
“CO” will display for
1.5 seconds

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3.3 % Saturation Calibration
The DO 6 PLUS can be easily calibrated in air. For the most accurate DO
readings, ensure that the barometric pressure value is accurate.
The barometric pressure factory default is 760 mm Hg, which results in
a theoretical calibration value of 100% saturation in air. If the barometric
pressure setting has been changed from 760 mm Hg, the meter will
automatically adjust to a new % saturation calibration value instead of
100%. This new value is correct for the adjusted barometric pressure.
3.3.1 100% Calibration
1. Rinse the probe thoroughly with DI water or rinse solution.
2. Press MODE to select % saturation.
3. Hold the probe in the air with the tip facing downwards. Wait for
the reading to stabilize.
4. Press CAL. The CAL indicator
and intended percentage
calibration point (100%) will
display brief y, before CAL
f ashes. The % value based on
the factory default calibration is
shown.
5. Press HOLD/ENTER to conf rm
the calibration. The meter will
display “CO”, automatically
calibrate to 100.0% air
saturation, and then return to the
measurement mode.
%
CAL
A
%
HOLD
ENTER
CAL
CAL
%
Calibration point will be
displayed for 1.5 seconds
%
A value with respect to the
factory default calibration
will be displayed
“CO” will displayed for
1.5 seconds
A

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3.3.2 0% Calibration
1. Rinse the probe thoroughly with DI
water or rinse solution.
2. Press MODE to select % saturation.
3. Dip the probe into a zero oxygen
solution. Stir gently with the probe. Wait
for the reading to stabilize.
4. Press CAL. The CAL indicator and
intended percentage calibration point
(0%) will display brief y, before CAL
f ashes. The % value based on the
factory default calibration will be shown.
5. Press HOLD/ENTER to conf rm the
calibration. The meter will display
“CO”, automatically calibrate to
0.0% saturation, and then return to the
measurement mode.
A value with respect to the
factory default calibration
will be displayed
%
CAL
A
%
HOLD
ENTER
CAL
CAL
%
Calibration point will be
displayed for 1.5 seconds
%
“CO” will displayed for
1.5 seconds
A

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3.4 mg/L or ppm Calibration
Performing a 100% saturation calibration will simultaneously calibrate
the corresponding mg/L (ppm) concentration value. Therefore, an
additional mg/L (ppm) calibration isn’t required in most circumstances.
If desired, a calibration adjustment in mg/L (ppm) can be performed
without affecting the % saturation calibration value.
1. Perform the 100% Saturation
Calibration. See Section 3.3.1 — 100%
Calibration.
2. Rinse the probe thoroughly with DI
water or rinse solution.
3. Dip the probe into a sample of known
oxygen concentration (i.e. determined
by titration or another instrument). Stir
the solution gently with the probe. Wait
for the reading to stabilize.
4. Press MODE to select mg/L (ppm).
5. Press CAL. The CAL indicator and
current concentration will display
brief y, before CAL f ashes. The
concentration value based on the
factory default calibration will be
shown.
6. Press or to adjust the reading to
match the known oxygen concentration
value.
7. Press HOLD/ENTER to conf rm the
calibration. The meter will display
“CO”, and automatically calibrate to
the entered value, then return to the
measurement mode.
NOTE: The minimum calibration value is 2 mg/L. To prevent erroneous
calibrations, the calibration is limited to ±40% adjustment of the factory
default value.
mg/l
mg/l
mg/l
CAL
CAL
HOLD
ENTER
CAL
mg/l
“CO” will display
for 1.5 seconds
A
A
A value with respect to the
factory default calibration
will be displayed

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4. MEASUREMENT
The DO 6 PLUS offers automatic or manual temperature compensation.
See Section 5.2 — Automatic Temperature Compensation.
%
A
Automatic Temperature
Compensation activated
4.1 Temperature Compensation
Insert the phono plug of the probe for Automatic Temperature
Compensation (ATC). The “A” annunciator will display normally when
active, or blink if the phono plug is disconnected.
Deactivate “A.ATC” for manual temperature compensation. The
“A” annunciator will not be displayed when the meter is in manual
temperature compensation mode.
For manual temperature compensation, manually enter the desired
process temperature from 0 to 50 °C into the meter. The default is 25 °C.
1. Press MODE to select temperature.
2. Press CAL. The “CAL” indicator will start
blinking and the display will show the last
manually set temperature value.
3. Check the temperature of the sample using
an accurate reference thermometer. Wait
for the value to stabilize. Press or to
manually set the temperature value.
4. Press HOLD/ENTER to conf rm the
calibration. The meter will display “CO”
and automatically set the entered value,
then return to the measurement mode.
CAL
CAL T
T
T
T
CAL
HOLD
ENTER
Last set manual
temperature setting
“CO” will display for 1.5
seconds

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4.2 Taking Measurements
Follow these general rules when taking measurements: keep the
membrane free from contact with solid objects, provide stirring of the
solution—this helps to overcome the oxygen consumption of the probe
and prevents air bubble entrapment, do not strike the probe against hard
surfaces, and do not submerge the cable for extended periods.
1. Rinse the probe thoroughly with DI
water or rinse solution.
2. Select the appropriate measurement
mode. Press MODE to toggle between
modes:
a. Percentage Saturation (%)
b. Concentration (mg/L) or
(ppm)
c. Temperature (T)
3. Dip the probe into the sample. Stir the
solution gently with the probe.
4. Allow the reading to stabilize and
observe the reading.
To change the concentration units see Section
5.3—Selection of mg/L or ppm.
4.3 Pressure & Salinity Compensated Measurements
During measurement the dissolved oxygen reading is automatically
compensated for salinity and pressure based on values entered in the
setup menu. For the most accurate DO readings, ensure that pressure
and salinity are adjusted accordingly from the setup menu. The factory
default values are 760 mm Hg (101.3 kPa) barometric pressure (sea
level) and 0.0 ppt salinity (no salinity). See Section 5.9 — Pressure &
Salinity Adjustment.
%
A
mg/l
A
MODE
MODE
TA

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4.4 Holding a Reading
To hold the displayed reading momentarily, press HOLD/ENTER
during any measurement. The %, mg/L, ppm or T annunciator will blink,
indicating that the value is being held.
%
A
Annunciator Blinks when
meter is in “HOLD” mode
Press HOLD/ENTER again to deactivate the HOLD function. The meter
will revert to the current active measurement and the annunciator will
stop blinking.
If the auto-off feature is activated, the meter will turn off automatically
after 20 minutes of non use The HOLD value is not retained when the
meter is shut off automatically or manually.
5. SETUP
There are two setup menus. One menu is derived from the % saturation
and temperature modes; the other menu is derived from the mg/L (or
ppm) concentration mode.
1. Press MODE to display % saturation or temperature. Press ON/
OFF to power off.
OR
Press MODE to display mg/L (or ppm). Press ON/OFF to
power off.
2. With the meter off, keep the MODE key pressed. Press and
release ON/OFF, then release MODE. The meter should display
“SEt.P” after ON/OFF is released and “COF.1” after MODE is
released.
Press CAL one or more times as needed during setup mode to exit and
return to measurement mode at any time.

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Setup Menu
Conf guration Menu
A. ATC Automatic Temperature
Compensation
b. DO Select mg/L or ppm units for
concentration mode
(available from concentration setup only)
View the latest calibration data according to the
respective setup menu.
View the electrode properties
FACT View the slope factor
OFS View the % saturation offset adjustment.
(available from % saturation concentration setup
only)
HI.mV View the mV value at 100% saturation
LO.mV View the mV value at 0% saturation
Selection of automatic power-off (20 min from the
last key press)
Reset Menu
A.CAL Calibration only reset to factory default
b.USR User settings reset to factory default
% saturation offset adjustment
(available from % saturation concentration setup
only)
Dissolved Oxygen Parameters
A.HG Barometric pressure adjustment in mmHg
A.PA Barometric pressure adjustment in
kilopascal
b.SAL Salinity adjustment
(available from concentration setup only)