Apera Instruments SX716 User manual

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SX716 Portable Dissolved Oxygen Meter
User Manual
APERA INSTRUMENTS, LLC
aperainst.com

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Table of Contents
1 Brief Instruction ................................................................................................................ - 3 -
2 Technical Specifications .................................................................................................... - 4 -
3 About the Meter ............................................................................................................... - 5 -
4 Dissolved Oxygen .............................................................................................................. - 7 -
4.1 Preparation before use ........................................................................................................... - 7 -
4.2 DO Calibration (Saturated Oxygen) .......................................................................................... - 9 -
4.3 DO Measurement ................................................................................................................... - 9 -
4.4 Notes about DO Measurement ............................................................................................. - 10 -
4.5 DO Electrode Maintenance ................................................................................................... - 10 -
4.6 Zero Oxygen Calibration ........................................................................................................ - 11 -
4.7 Salinity Calibration ................................................................................................................ - 12 -
4.8 Barometric pressure manual compensation .......................................................................... - 12 -
4.9 Parameter Setting ................................................................................................................. - 13 -
5 What’s in the kit ............................................................................................................. - 16 -
6 Warranty ........................................................................................................................ - 16 -
7 Appendix ........................................................................................................................ - 17 -
7.1 Appendix 1 Content of Saturated Oxygen in Water at Different Temperature ........................ - 17 -
7.2 Appendix 2 Content of Saturated Oxygen at Different Barometric pressure ........................... - 18 -
7.3 Appendix 3 Content of Oxygen at Different Altitude .............................................................. - 19 -
Scan the QR code below to watch the tutorial video on Youtube.

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1 Brief Instruction
Thanks for purchasing Apera Instruments SX716 Portable DO Meter (will be called “the
meter” in short in the following content).
Before using the meter, please read this instruction manual carefully in order to help
you properly use and maintain it.
The meter can measure the parameters of DO and temperature of water solutions with
high accuracy. It is the most cost-effective choice of a high-quality portable DO meter. It
is suitable for applications in aquaculture, mining industry, power plants, environmental
monitoring, etc., especially suitable for in-field use.
The meter has the following features:
1.1. Built-in microprocessor chip with the intelligent functions of auto. DO calibration,
auto. temperature compensation, auto. salinity compensation, manual baromatric
pressure compensation, data storage, function settings, auto. power off, and low
voltage display etc.
1.2. Adopts digital filter technology to intelligently improve meter’s response speed and
accuracy. The smiley face icon will appear when the reading is stable.
1.3. Built with a polaragraphic DO electrode with temperature and salinity sensors,
which enables auto. temperature and auto. salinity compensation.
1.4. The polarographic DO electrode has a special electrode calibration sleeve. The
electrode polarization only takes 5 minutes. Electrode adopts a combo-style
membrane cap, which is very convenient to use. Each DO electrode comes with
three backup membrane caps.
1.6. Meter’s LCD screen has clear and bright backlit display.
1.7. Built-tough. IP57 waterproof and dust-proof.

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2 Technical Specifications
2.1 Dissolved Oxygen
Measuring range
(0 to 19.99) mg/L (ppm); (0 to 200.0) %
Resolution
0.1/0.01 mg/L (ppm) 1/0.1%
Accuracy
±0.30 mg/L (ppm), including electrode error
Response time
≤30s (25˚C, 90% response)
Temp. compensation range
(0 to 45) ˚C (automatic)
Salinity compensation range
(0 to 45) ppt (automatic)
Barometric pressure
cocompensation range
(66 to 200) kPa (manual)
Automatic calibration
Air saturated by water; water saturated by air
Electrode type
Polarographic
2.2 Other Technical Parameters
Data storage
100 sets
Data content
Serial number, measuring value, measuring unit,
and temperature
Power Supply
Two AA alkaline batteries (1.5V x2)
Dimensions and weight
Meter: (65×120×31) mm/180g
Carrying case: (255 x 210x 50) mm/790g
Quality and safety certification
CE, ISO 9001:2015
2.3 Working Condition
Working temperature
5 to 35˚C
Working humidity
≤85%
IP rating
IP57 water-resistant

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3 About the Meter
3.1 Screen Display
① —— Parameter icon
② —— Measuring value
③ —— Serial number and icon as measuring value to be stored and recalled and
indication icon for special states.
M+ — measuring value to be stored; RM — Stored value to be recalled;
④ —— Measurement unit
⑤ —— Temperature measuring value and unit
⑥ —— Measurement stabilization icon
⑦ —— Electrode calibration indication icon
⑧ —— Indication icon of low battery power; appears when the voltage is less than 2.6V,
calling attention to replace the batteries.
3.2 Keypad
The meter has 5 operation keys in total.
Short press: press time <1 seconds; Long press: press time >2 seconds
3.2.1. — Power on/off
3.2.2. — Calibration key.
(a) When in measurement mode, press this key to enter calibration mode.
(b) When in parameter setting mode, press this key to make changes.

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3.2.3. — Function key
Press the key to enter the parameter setting mode P1, P2, P3…
3.2.4. — Backlight and confirmation key
(a) When in measurement mode, short press (less than 1.5s) to turn on/off the back
light display.
(b) When in calibration mode or the parameter setting mode, press this key to confirm,
and then the meter enters measurement mode;
(c) When in measurement mode, hold the key to change units in turn: mg/L→ppm→%,
when the desired unit appears, release the key to select it.
3.2.5. — The combination key of data logging and recalling
(a) Short press to save the readings, long press to recall the saved readings when in
the measurement mode.
(b) When in the parameter setting mode, press this key to change the number or
ON/OFF state.
3.3 Data Log, Recall and Delete
3.3.1. Save the measurement:
In measurement mode, when the reading is stable and smiley face icon stays on screen,
short-time press key to save the measurement data. M+ icon and the data serial
number will show up on the upper right corner. The meter can store up to 100 sets of
data.
3.3.2. Recall saved data:
(a) In measurement mode, long press the key, the meter will recall the last saved
data and the serial number. RM icon will appear in the upper right corner of the
screen. Short press or key again, the meter will recall all the data in
turn, hold or key to quickly review the data.
(b) In data recalling mode (RM and serial number in the lower right corner of the screen),
press key to return to measurement mode.
3.3.3. Delete the saved data:
In data recalling mode, hold key for 5 seconds, CLr will show up for 2 seconds,
meaning that all the saved data have been eliminated. Then the meter will return to
measurement mode.

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4 Dissolved Oxygen
4.1 Preparation before use
4.1.1. Electrode connection

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4.1.2. Connect the DO electrode. Then Press key to power on the meter.
4.1.3. Choose DO unit: Hold to switch among mg/L, ppm and %. When the desired
unit shows up, release the button to confirm the unit selection.
4.1.4. Check the sponge
Check on the DO500 DO electrode: see picture (4-1). Screw off the bottom lid of electrode
calibration sleeve, inspect whether the sponge inside is moist. If it is dried out, add in several
drops of distilled water to the sponge to maintain the satured air inside the calibration sleeve
(Do NOT add too much water so it won’t be dripping).
4.1.1 Electrode polarization
After each power on, the DO electrode must be polarized for 5 minutes before measuring or
calibration. So do not to turn off the meter in the middle of your DO measurement. Otherwise,
you need to polarize the DO electrode again after next power on (The auto. power off
function in DO mode has been turned off by default).
How to polarize the DO electrode –– Just connect the DO electrode to the powered-on
meter without measuring or calibrating.
Electrode polarization is to consume the remaining oxygen inside the inner solution of the
membrane cap so as to ensure fast response and high accuracy. If a new membrane cap is
replaced, or new inner solution is added, the polarization time should be 30 minutes instead
of 5 minutes.
1 — DO500 DO electrode
2 — Calibration sleeve cap
3 — Calibration sleeve
4 — Water stored sponge
5 — Calibration sleeve bottom lid
6 — Temp er ature elec tr o de
7 — Membrane cap
8 — Cathode (gold)
9 — Anode (silver)
10 — Salinity electrode

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4.2 DO Calibration (Saturated Oxygen)
Power on the meter, press key, the meter enters calibration mode, CAL will be flashing
at the upper-right corner. Insert the DO electrode to the calibration sleeve, and tighten the
sleeve cap. Let the electrode sit for 3 to 5 minutes.
When the reading is fully stabilized, press key again to finish the calibration. A flashing
100% will show up, and the calibration will be finished in several seconds and the meter will
return to measurement mode. If the reading is unstable, please wait for several more
minutes. Do NOT press key until the reading is fully stabilized.
4.3 DO Measurement
4.3.1. Measuring DO in flowing water
Power on the meter. Place the DO electrode into the flowing water. The water surface level
should be higher than the location of the temperature electrode. The angle for the electrode
and water surface should be 45° to 75°. Hold the electrode in the flowing water and wait for
a stable reading, then press to record the measurement. If the reading cannot be
stabilized, keep swirling the electrode slowly in water to help you get a stable reading
(typically takes 1-5 minutes).
4.3.2. Measuring DO in static water
Power on the meter. Place the DO electrode into water. The water surface level should be
higher than the location of the temperature electrode. The angle for the electrode and water
should be 45° to 75°. Keep swirling the electrode in water slowly (>5cm/s) for 1 to 5 minutes.
When the reading is fully stabilized, record the measurement (do NOT stop the swirling while
recording the measurement).
Never stop the DO electrode swirling in static water while measuring. Otherwise the
dissvolved oxygen will be consumed by the DO electrode and the reading will keep dropping.

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4.4 Notes about DO Measurement
a) When calibrating, the environment temperature and water temperature should be
close to each other (≤10˚C). If the difference is large, please dip the electrode into
the sample water for about 10 minutes, then calibrate the electrode according to
Section 4.2.
b) Temperature has a large impact on DO measurement. When the electrode
temperature and water temperature have larger difference, the reading time must be
greater than 3 minutes. Otherwise, there could be some large errors.
c) Salinity and barometric pressure also affect DO measurement. The meter has
automatic salinity compensation and manual barometric pressure compensation. For
details, refer to Section 4.7 and 4.8.
d) When the meter is performing abnormally, please set the mode P7 to be “On” to
restore meter to factory default setting, and then do the calibration again before
measuring.
4.5 DO Electrode Maintenance
4.5.1 Always maintain a moist sponge
Screw off the bottom lid of electrode calibration sleeve (see picture 4-1), inspect whether
the sponge inside is moist. If it is dried out, please add in several drops of distilled water to
the sponge to maintain the satured air inside the calibration sleeve (Do NOT add too much
water so it won’t be dripping).
4.5.2 Remove air bubbles
Inspect the inner solution within the electrode membrane cap. Make sure it doesn’t have air
bubbles. If there are air bubbles, please screw off the membrane cap and add in new inner
solution to remove the bubbles. Then screw the cap back on.
4.5.3 Clean the gold cathode
When the gold cathode is contaminated, use the polishing paper (DO504) to lightly wipe the
gold cathode (along the arc of the gold surface); clean the gold surface with a clean tissue