The process of measuring dissolved oxygen with imported portable dissolved oxygen meters usually follows the standardized operation of "preparation calibration measurement closing". The following are the specific steps and key details:

1、 Preparation stage: Ensure optimal condition of instruments and electrodes

1. Instrument inspection

Confirm that the battery is fully charged to avoid data loss caused by power outages midway.

Check if the display screen and button functions are normal to ensure stable operation of the instrument.

2. Electrode inspection and activation

Membrane integrity: Check whether the breathable membrane (fluorescent membrane or polarographic membrane) at the front end of the electrode is intact, without damage, bubbles, or aging. If the membrane is damaged, it needs to be replaced and supplemented with specialized electrolyte in a timely manner.

Electrolyte adequacy: Confirm that the electrolyte inside the electrode is not turbid or crystalline. If it is insufficient, it should be replenished to the specified scale.

Electrode activation: New electrodes or electrodes that have not been used for a long time need to be activated in advance. Soak the electrode in distilled or deionized water for 1-2 hours to fully wet the membrane and ensure measurement accuracy.

3. Environmental condition records

Record the temperature and pressure of the measurement environment (some instruments can automatically detect them, but manual input is required when there is no automatic function), for temperature/pressure compensation of dissolved oxygen concentration.

2、 Calibration stage of imported portable dissolved oxygen meter: establishing measurement benchmark

1. Air calibration (recommended)

Operation steps:

Remove the electrode from the storage solution, rinse it clean with distilled water, and gently absorb the surface moisture with filter paper (do not wipe the film to avoid damage).

Keep the electrode head (membrane part) exposed to clean air, away from fans, heat sources, and direct sunlight (to avoid airflow interference).

Turn on the device, enter "calibration mode", and select "air calibration". The instrument will automatically calculate the saturated dissolved oxygen value based on the current temperature and pressure.

Wait for the reading to stabilize and press the 'confirm' button to complete the calibration.

Applicable scenarios: Suitable for most conventional water body measurements, easy to operate and highly accurate.

Standard solution calibration (high-precision requirement)

Operation steps:

Prepare a dissolved oxygen standard solution of known concentration, pour the standard solution into a clean beaker, and keep the temperature consistent with the environment.

After rinsing the electrode, immerse it in standard solution (membrane immersion, avoid touching the cup wall), gently stir to make the solution uniform.

Enter "Calibration Mode", select "Standard Solution Calibration", and enter the concentration value of the standard solution.

After the reading stabilizes, press "confirm" to complete the calibration.

Applicable scenarios: Suitable for scenarios that require high measurement accuracy, such as laboratory research and precision industrial control.

3、 Measurement stage of imported portable dissolved oxygen meter: obtaining dissolved oxygen data

Water sample collection and processing

Sampling requirements:

Collect water samples on site to avoid changes in dissolved oxygen caused by prolonged storage.

Avoid vigorous agitation during sampling to prevent the mixing of bubbles (which can affect the measurement results).

If the water sample contains bubbles, gently shake or let it stand to allow the bubbles to escape.

Special water treatment:

Sewage or water samples containing a large amount of impurities: need to be filtered first (such as pre-treatment with a filter screen) to avoid contaminating the electrode membrane (causing reading drift or failure).

Aquaculture water body: Take water from the middle of the pond/water tank to avoid interference from the oxygen deficient area at the bottom.

2. Measurement operation

Operation steps:

Pour the water sample to be tested into a clean beaker (or measure directly in the sampling container) to avoid overflow or the formation of bubbles.

After electrode rinsing (rinse 1-2 times with the water sample to reduce contamination), slowly immerse in the water sample.

Gently stir the water sample to ensure that the water around the electrode is evenly distributed (avoiding local differences in dissolved oxygen).

Wait for the screen reading to stabilize (the value no longer fluctuates, some instruments have a "stable" prompt), and record the displayed dissolved oxygen concentration.

Repeated measurement: It is recommended to measure the same water sample 2-3 times and take the average value (to reduce accidental errors).

Water flow requirements:

Active water body: The water sample flow rate should be greater than 5cm/s, the electrode should be at a 45 ° -75 ° angle to the water flow direction, and the electrode should be slightly shaken for 3-5 minutes until the reading stabilizes.

Static water: The electrode moves rapidly in the water for 3-5 minutes until the reading stabilizes.

Slow moving water bodies: Operate according to the method of moving water bodies, but the electrode movement speed is slightly faster.

4、 Final stage of imported portable dissolved oxygen meter: maintenance and storage

1. Electrode cleaning and drying

After the measurement is completed, rinse the electrode with distilled water or deionized water to remove any residual water samples and impurities on the surface.

Use filter paper to absorb surface moisture (do not wipe the film) to prevent damage to the film.

2. Electrode storage

Short term storage (1-3 days): Immerse the electrode in a dedicated electrolyte or distilled water (membrane immersion to prevent membrane drying).

Long term storage: Remove the electrode protective cap, absorb the electrolyte, and store it dry (to prevent the film from getting damp and aging).

3. Instrument organization

Turn off the power of the instrument, clean the surface of the instrument, and organize the main unit, electrodes, calibration solution, and other accessories neatly.

Avoid the instrument from being affected by collisions, compression, or humid environments.