Dissolved Oxygen Measurement
The HL103 pocket DO/temperature tester is suitable for measuring the dissolved oxygen
content of water, wastewater, brine and other liquids.
If the meter is used to measure seawater or other water containing large amounts of salt,
please set the salinity coefficient before use.
Some gases and vapours such as chlorine, sulfur dioxide, hydrogen sulfide, ammonium,
carbon dioxide and iodine can permeate the membrane via diffusion.
The presence of the above gases will interfere with the measurement of dissolved oxygen.
If the sample contains solvent, grease, sulfide and algae, the membrane on the probe will be
blocked, damaged or eroded.
1. Press ON/OFF key to turn on the tester, wait for 15 minutes to polarise the probe.
2. If necessary, to set the atmospheric pressure and salinity coefficient in the setup menu
(Refer to “SETUP MENU” section).
3. Immerse the probe in the sample solution, ensure the temperature sensor on the probe is
fully immersed.
4. Stir the solution gently, wait for the reading to stabilise, record the measured value on the
display.
Hold Function
The tester contains two data hold modes. When the Auto-Hold function is enabled, the tester
will automatically sense a stable endpoint reading and freeze it, “HOLD” indicator appears on
the display. If the Auto-Hold function is disabled, press HOLD key, the tester will immediately
freeze currently displayed value. Press the key again to resume measuring.
mg/L
Temperature
Sensor
