Apera Instruments DO850 User manual

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DO850
Portable Optical Dissolved Oxygen Meter
Instruction Manual
APERA INSTRUMENTS, LLC
aperainst.com
v3.0

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Contents
1Overview .................................................................................................................. - 3 -
1.1 Luminescent optical sensor. ........................................................................................................... - 3 -
1.2 Intelligent Instrumentation ............................................................................................................ - 3 -
2Technical Specifications ........................................................................................... - 4 -
3Instructions ............................................................................................................... - 4 -
3.1 LCD Screen...................................................................................................................................... - 4 -
3.2 Key Operation................................................................................................................................. - 5 -
3.3 Batteries ......................................................................................................................................... - 6 -
3.4 Instrument Socket .......................................................................................................................... - 6 -
3.5 Reading Stability Mode .................................................................................................................. - 6 -
3.6 Auto Lock Mode ............................................................................................................................. - 6 -
3.7 Backlighting .................................................................................................................................... - 6 -
3.8 Automatic Power-Off...................................................................................................................... - 6 -
4Optical Dissolved Oxygen Probe.............................................................................. - 7 -
4.1 Probe Structure .............................................................................................................................. - 7 -
4.2 Probe Maintenance........................................................................................................................ - 7 -
4.3 Sensor Cap...................................................................................................................................... - 8 -
5Preparation for Calibration........................................................................................ - 8 -
5.1 Dissolved Oxygen Units Selection .................................................................................................. - 8 -
5.3 Temperature Unit Selection............................................................................................................. - 9 -
5.4 Air Pressure Compensation ............................................................................................................. - 9 -
6Calibration ................................................................................................................ - 9 -
6.1 Saturated Oxygen Calibration......................................................................................................... - 9 -
6.2 Zero -Oxygen Calibration................................................................................................................ - 9 -
6.3 Special Notes for Calibration ........................................................................................................ - 10 -
7Measurement.......................................................................................................... - 10 -
8Parameter Settings..................................................................................................- 11 -
9 Complete Kit............................................................................................................ - 13 -
10 Warranty................................................................................................................ - 13 -
11 Trouble Shooting ................................................................................................... - 14 -

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1 Overview
Thank you for purchasing Apera Instruments DO850 Portable Optical Dissolved Oxygen Meter. The
DO850 measures dissolved oxygen in water using luminescence technology through an optical
sensor and displays data with intelligent instrumentation. Compared to conventional electrochemical
dissolved oxygen meter, the DO850 is more accurate, stable and easier to use.
Before you use the instrument, please carefully read the instruction manual to help you properly
perform tests and maintainenance.
1.1 Luminescent optical sensor.
⚫Stability and Accuracy: Oxygen is not consumed during measurements. It is not affected by
sample flow rate and thus provides a stable measurement.
⚫Easy to Use: No electrolytes or membranes are required; frequent calibration is not
necessary.
⚫Interference-Free: Sensor cap is coated with a light-shielding layer and minimizes the impact
from external light sources. The use of non-chemical sensors helps reduce a variety of heavy
metal ions interference in the aqueous environment with H2S and NH4 and other chemical
substances.
⚫Long service life: except for mechanical deterioration (such as scratches to the light shielding
layer), the sensor cap has up to 8000 hours of service life.
⚫Easy to calibrate and maintain. Probe is equipped with a calibration/storage sleeve, which
makes calibration and maintenance more convenient and reliable.
1.2 Intelligent Instrumentation
⚫Built-in microprocessor chip, featured with Auto. Temperature Compensation, Auto. Air
Pressure Compensation, Auto. Salinity Compensation and parameter setting, auto. power off,
and low power indication.
⚫Stable reading and automatic locking modes available.
⚫Clear large-size LCD display with white backlight.
⚫Meets IP57 waterproof rating; In addition, a rugged instrument suitcase is provided.
Special Notes
⚫Sensor cap surface coating can not withstand high temperature, so the optical dissolved
oxygen electrode can not test water with temperature over 50 ℃.
⚫When the electrode is not in use, it should be kept in the storage sleeve and the
sponge in the cap should be kept moist, so that the fluorescent cap will not dry out. If
the sponge is dried out or the probe is exposed in dry air for more than 8 hours, soak
the electrode in tap water for 24~48 hours (see section 4.2), otherwise it may cause
unstable measurements or slow response.
⚫Before getting readings or performing other operations, wait about 30 seconds after meter is
powered on.

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2 Technical Specifications
Dissolved
Oxygen
Dynamic Range
(0-20.00) mg/L (ppm), (0-200.0)%
Resolution
0.01/0.1mg/L (ppm), 0.1/1%
Accuracy
±2% reading or ±2% saturation,
whichever is greater
±2% reading or ±0.2 mg/L,
whichever is greater
Response Time
≤30 s (25℃, 90% response)
Calibration Points
Saturation Point & Zero Oxygen
Temperature Compensation
Automatic, (0 to 50)℃
Pressure Compensation
Automatic, (60 to 120) kPa
Salinity Compensation
Manual, (0 to 45) ppt
Temperature
Range
(0 to 50.0) ℃
Resolution
0.1 ℃
Accuracy
±0.5 ℃
Other
Batteries
AA x 3 (1.5V×3)
IP Rating
IP57
Dimensions and Weight
Meter: 88×170×33 mm/313g
With case: 360×270×76 mm/1.3kg
Product Certificate
RoHs, CE & ISO9001:2015
3 Instructions
3.1 LCD Screen
Fig.-1

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3.2 Key Operation
Short press: key press time < 2 seconds; Long press: key press time> 2 seconds.
Power on: Press to turn on. Power off: long press 2 seconds off.
Special notes: After meter power on, wait about 30 seconds to read value or operatation.
Table - 1 Key operation and functions
Key
Operation
Functions
Short
Press
⚫In the shutdown mode: press the key to boot
⚫In measurement mode: press to turn backlight on or off
Long Press
⚫Press and hold for 2 seconds to turn off
Short
Press
⚫In measurement mode: press the key to switch unit: %→mg/L
or %→ppm
Long Press
⚫In the measurement mode: press the key for 2 seconds to enter the
calibration mode
Short
Press
⚫To cancel any operation, press to return to measurement mode
Short
Press
⚫In the menu mode: press the key to change the serial number or
select the parameter
Short
Press
⚫In the menu mode: press the key to change the serial number or
select the parameter
Short
Press
⚫In measurement mode: press to enter menu mode;
⚫In calibration mode: press key to calibrate;
⚫In the menu mode: press key to confirm the parameter.
①
Measurement mode icon
⑦
Auto lock icon
②
Reading/Measured Value
⑧
Temperature Compensation
ATC — Auto Temperature Compensation
MTC — Manual Temperature Compensation
③
Symbol
④
Units of Measurement
⑤
Temperature unit
⑨
Reading Stability Icon
⑥
Temprature value / Symbol
⑩
Low Voltage Icon
Fig.-2

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3.3 Batteries
The instrument uses three AA alkaline batteries. Battery life > 200
hours (without backlight). When the display shows symbol as
shown in Figure-3, replace the battery.
3.4 Instrument Socket
The instrument uses an 8-pin socket that is protected by a gray rubber cap seal. Eight-pin
socket (right) - connect DO electrode. When inserting the probe connector, align the notch
on the connector to the socket, and twist the nut to tighten. There is a sealing ring between
the end face of the socket and the connector, which can effectively maintain the waterproof
rating of the socket.
3.5 Reading Stability Mode
When the measured value is stable, the LCD screen displays the icon
as shown in Figure-4. If there is no icon or icon flashing,
indicating that the reading is not stable yet, the measurement should
not be read or calibrated.
3.6 Auto Lock Mode
In parameter setting P4.2 you can select the auto-lock mode (Off-On) ,
Select On to turn on automatic locking. When the reading is stable
for more than 10 seconds, the meter automatically locks the measured
value and displays the HOLD icon, as shown in Figure - 8. When auto.
locked, press to unlock. Select Off to turn off automatic lock.
3.7 Backlighting
The Instruments LCD screen has a white backlight suitable for use in dark environments.
Turning on the backlight will consume more power. The instrument has automatic backlight
and manual backlight mode. In automatic backlight mode, when is pressed, backlight
will be on for a minute then automatically shuts off; In manual backlight mode, when is
pressed, backlight will be on and won’t turn off unless is pressed again. In the
parameter setting P4.3, you can select the auto backlight mode (On-Off), select On to turn
on auto. backlight; select Off to turn off auto. backlight.
3.8 Automatic Power-Off
In the parameter setting P4.4, you can select the auto power off function (On-Off), select On
to turn on auto. power off, the instrument will shut down automatically after 20 minutes’ non-
operation; select Off to disable this function.
Fig.-3
Fig.-4
Fig.-5

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4 Optical Dissolved Oxygen Probe
4.1 Probe Structure
The instruments DO803 optical dissolved oxygen probe has a cable length of 3m and built-
in temperature sensor for automatic temperature compensation. The electrode structure is
shown in Fig.-6
1. Bottom cover of the calibration sleeve
5. Locking cap
2. Sponge for water storage
6. Optical DO electrode
3. Sensor cap
7. O-ring
4. Calibration sleeve
Immersion line:
The tested solution should be above this line
4.2 Probe Maintenance
The sensor cap of the optical DO electrode must be kept in a moist environment. If the
surface coating of the sensor cap dries out, the reading will be unstable, or the response
rate will be slow. The electrode calibration sleeve is used to store the probe.
(A) Short-term storage (less than 30 days): The probe head is kept in the calibration
sleeve. Always keep the sponge inside the calibration sleeve moist. Several drops of
clean water should be added to a dry sponge (let the sponge be damp, but not
dripping), and tighten the lock cap, so that the sensor cap is kept in the moist-
saturated air.
(B) Long-term storage (greater than 30 days): The probe head is kept in the calibration
sleeve. Check whether the storage sponge is moist every 30 days or user can store
the electrode in a beaker containing clean water.
(C) Before the first use, unscrew the calibration sleeve to check if the sponge is damp. If
the sponge is dry or if the electrode is exposed to dry air for more than 8 hours, the
surface coating of the sensor cap may be dried out. So the electrode should be
Fig.-6

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soaked in clean water at room temperature for 24 hours. If the water temperature is
low, soaking time should be 48-72 hours.
(D) The sponge can not be allowed to get stained or moldy, otherwise it will consume or
produce oxygen. If stained or moldy, please replace it immediately (some back-up
sponges are included in the kit).
4.3 Sensor Cap
(A) The sensor cap is a key part of the optical DO probe. The surface coating of the cap
cannot be scratched or mechanically worn. Otherwise, the service life of the sensor
cap will be reduced or the probe will be damaged. Please pay special attention to it
when using the probe.
(B) The surface coating of the sensor cap cannot withstand high temperature, so the
optical DO probe can not be tested in water above 50˚C/122˚F.
(C) If the surface of the sensor cap is contaminated, please do not use alcohol or organic
solvents to clean, otherwise it may damage the probe. It can be gently wiped with a
soft clean cloth. To disinfect the probe, immerse it in 3% hydrogen peroxide for 15 to
30 minutes and then rinse off with clean water.
(D) The sensor cap has a service life of more than 8000 hours. When the probe is not
being used, the service life will not be reduced, so the actual use time of the sensor
cap is far more than a year. The major factor affecting the service life of the sensor
cap is the surface coating being damaged under external force. So the key is to
protect the sensor cap from external damage.
(E) If the sensor cap is damaged or deteriorated, users need to purchase a new one.
Every new cap has a set of calibration codes which need to be input into the
instrument. The specific input method will be described in the instruction manual of
sensor cap.
(F) Users should not take off the sensor cap when it is not in use. Nor should one swap
the caps from different instruments. When being installed, the sensor cap must be
tightened, and the interior can not be contaminated or wet.
5 Preparation for Calibration
5.1 Dissolved Oxygen Units Selection
Dissolved oxygen units displays in two forms: mg / L and %, and ppm and %. Press to
switch between mg / L → %, or ppm → %. Users can choose mg / L or ppm in parameter
setting P3.1, but only a percentage (DO %) is displayed in calibration.

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5.2 Resolution Selection
The resolution unit can be selected in parameter setting P3.2: 0.01 or 0.1mg/L (ppm). After
setting, the meter will display resolution of 0.1 or 1 in according to %.
5.3 Temperature Unit Selection
The temperature unit can be selected in parameter setting P4.1: ˚C or ˚F
5.4 Air Pressure Compensation
The instrument has automatic air pressure compensation function. The air pressure has
been calibrated before the product left the factory. So in general users do not have to
calibrate air pressure any more. If necessary, calibrate it according to standard value
measured by aneroid barometer. Refer to parameter setting P3.4 for the procedure of
aneroid barometer calibration.
5.5 Salinity Compensation
The instrument has manual salinity compensation. It is set in the parameter P3.3 (0 to 45
ppt). To obtain accurate readings in mg/L and ppm, it is necessary to know the salinity of the
test sample and input salinity value into the instrument. As the salinity of the solution
increases, the level of DO decreases. Generally, salinity of freshwater is 0 to 0.5ppt, salinity
of seawater is 35ppt.
6 Calibration
6.1 Saturated Oxygen Calibration
(A) This procedure requires the use of a calibration sleeve to allow the probe to be calibrated
in a humidity-saturated atmosphere.
(B) Check if the sponge in the calibration sleeve is damp. Attach the calibration sleeve to
the probe. Tighten the locking cap. Be careful not to have water droplets on the head of
the sensor cap. Wait for 5 to 10 minutes after turning on the instrument in order to
saturate the air in the calibration sleeve with water vapor. In addition, wait for the
temperature to completely stablize.
(C) Long press to enter the calibration mode, and CAL is flashing in the upper right
corner. Wait for the stable to appear and stay on, press to finish calibration,
once 100% starts flashing, the saturated oxygen calibration is completed.
6.2 Zero -Oxygen Calibration
Zero-Oxygen calibration is only performed when a probe or sensor cap is replaced, the
probe has not been used for a long time, or users have a requirement for high accuracy in
low DO range (0 to 2.0 ppm). Zero-Oxygen calibration is done at the factory before shipment,
so it is not necessary to perform it during initial use. Zero-oxygen calibration should follow

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these steps:
(A) Preparation of 100ml of oxygen-free water: in the 100ml beaker, weigh 2g of
anhydrous sodium sulfite (Na2SO3) and add 100ml of distilled or deionized water to
dissolve. Oxygen-free water is only effective within 1 hour.
(B) Put the electrode into the oxygen-free water, wait for 3 to 5 minutes after the
instrument is turned on, and wait for the temperature and DO reading to completely
stabilize. The DO reading should be very close to 0, 0.1mg/L (ppm) or so.
(C) Long press to enter the calibration mode. CAL will be flashing at the upper right
corner. Wait for a stable . Press and the zero-oxygen calibration is
completed.
6.3 Special Notes for Calibration
(A) Optical dissolved oxygen probes have better stability and smaller calibration drift
compared to conventional electrochemical dissolved oxygen electrodes, which means
that the instrument can maintain its calibration data for a few months. However, for
optimal accuracy, it is recommended that the oxygen saturation calibration be performed
according to section 6.1 before use every day.
(B) Drying of the surface coating of the sensor cap can adversely affect the stability of the
measurement. Please pay special attention to this situation. See Section 4.2 (Probe
Maintenance) for details.
(C) The instrument has factory default setting function, select YES in parameter setting P3.5,
the meter will be calibrated to the theory value.
7 Measurement
7.1 When measuring, place the probe in your sample solution, stir quickly for a few
seconds in the solution to remove bubbles from the measuring surface of the sensor cap.
Then hold the probe still and wait for a stable measurement. The solution must be above
the immersion line of the probe.
Note: the brief stirring of the probe in solution is only to eliminate bubbles. Unlike
conventional galvanic/polarographic electrodes, the measuring via optical dissolved
oxygen probes does not require constant stirring of the solution or flowing fluid.
7.2 Users can read the measurements when appears and stays on. Note that the
measurement time is related to temperature. When the solution temperature and the probe
temperature is close, it takes about one minute to get the readings stablized. When the
solution temperature and the electrode temperature differ a lot, it takes about 3 minutes to
reach a stable reading. This is because the reading of dissolved oxygen is heavily