GAOTek Dissolved Oxygen Meter with Salinity Correction (Reset)

Additional Information

Applications:

• Environmental monitoring and ecological research
• Water and wastewater treatment
• Education applications

Accessories:

• Dissolved Oxygen Probe
• Electrolyte Solution
• Membrane Cap
• DC 9 V Power Adapter

Display

This meter is equipped with a clear and bright LCD display that shows measured values, mode indicators and help messages.

Keypad

The meter has a succinct membrane keypad, names and symbols describe each function key controls.

KEY	FUNCTIONS
	Power the meter ON/OFF. Freezes the measured value on the display, press the key again to resume measuring. In the calibration or temperature setting mode, exits current mode and returns to measurement.
MODE	Toggles between % saturation and concentration modes.
	Press the key to enter the calibration mode. Press and hold the key to enter the setup menu.
°C	Press the key to set the temperature or enter the temperature calibration mode.
▲	Press the key to increase the setting value.
▼	Press the key to decrease the setting value.
ENTER	Confirms the calibration, setting value or displayed option.

Connecting the Electrode Holder

The meter comes with an easy-to-use holder for mounting the DO probe. If necessary, please follow the steps below to install the electrode holder.

1. The base of the electrode holder with an irregular round hole.
   
2. The electrode arm has a plastic rod.
   
3. Insert the plastic rod into the irregular round hole and swivel the electrode arm 90°. Electrode holder is now ready to swing into the desired position.
   

ADJUSTMENT OF ELECTRODE ARM:

After installation, if the electrode arm automatically rises or falls, you need to adjust the screws until arm locates at any position.

1. Remove the plastic cover from the electrode arm.
   
2. Use the screwdriver to tighten the screw moderately.
3. Insert the plastic cover to the previous position. Installation is completed.

Connecting the DISSOLVED OXYGEN Probe

1. Place the DO probe into left or right sides of the electrode arm.
   
2. Insert the 6-pin connector into corresponding connector socket, ensure the connector is fully seated. After the connection is completed, DO NOT pull on the sensor cord. Always make sure that the connector is clean and dry.
   

Refilling Electrolyte Solution for DO Probe

1. Unscrew the membrane cap from the bottom of the dissolved oxygen probe.
   
2. Fill the membrane cap halfway with an electrolyte solution.
   
3. Screw the membrane cap onto the probe, excess electrolyte will drain out.
   
4. Be sure the cathode of the probe makes contact with membrane cap, the electrolyte solution in membrane cap should be without an air bubble.
   

Connecting the Power Adapter

1. Before plugging in the power adapter, ensure the voltage of power adapter matches your local main voltage.
2. Insert the connector of power adapter into the meter power socket, the meter is now ready for use
   

Prior to Use

Turn on the meter 10 to 15 minutes and wait for the probe to polarize.

Power On/Off

• Press MEAS key to turn on the meter, the display shows measured values, mode indicators and help messages.
• Press and hold the MEAS key for 3 seconds, the meter will turn off.
• If you do not press any key within the specified time period, the meter will turn off automatically.

Setup Menu

This device contains an integrated setup menu that allows you to customize each displayed option to meet measurement requirements.

Setting the Default Parameters:

1. Press and hold the key for 3 seconds to enter setup menu, the meter shows selected salinity coefficient.
2. Press ▲ or ▼ key to set the parameter, press ENTER key to confirm. The meter goes to barometric pressure option, the display shows 760 mmHg.
3. Press ▲ or ▼ key to set the barometric pressure value, press ENTER key to confirm. The meter goes to calibration point selection mode, the display shows 1 point calibration.
4. Press ▲ or ▼ key to select the number of calibration points, press ENTER key to confirm. The display shows concentration unit “mg/L”.
5. Press ▲ or ▼ key to select the measurement units, press ENTER key to confirm. The meter shows “HOLD/NO” indicating that the auto-hold function is disabled.
   If the auto-hold function is enabled, the meter will automatically sense a stable endpoint reading and freeze it. If you disable this function, the meter allows you to freeze the reading by pressing the HOLD key.
6. Press ▲ or ▼ key to enable or disable the auto-hold function, press ENTER key to confirm. The meter shows “OFF/NO” indicating that the auto-off function is disabled.
   When the auto-off function is enabled, if you do not press any keys within 3 hours, the meter will automatically turn off.
7. Press ▲ or ▼ key to enable or disable the auto-off function, press ENTER key to confirm. The meter shows “RST/NO” indicating that the meter should not be reset.
8. Press ▲ or ▼ key to enable or disable the reset function, press ENTER key to confirm. The meter returns to measurement mode. The setting is completed.

EXIT THE SETUP MENU:

During the setup mode, if you want to exit setup menu, press MEAS key, the meter will return to measurement mode immediately.

DO Calibration in % Saturation Mode

This device can be calibrated quickly in air. In the percentage saturation mode, the meter is able to perform either 1 or 2 points calibration. For single point calibration, it is recommended that you perform 100% saturation calibration in the air. For the 2 points calibration, you need to use zero oxygen solution.

100% SATURATION CALIBRATION:

1. Make sure that you have selected 1 point calibration in the setup menu.
2. After the DO probe is connected to the meter, turn the meter on 10 to 15 minutes to polarize the sensor.
3. Press CAL key, the meter enters calibration mode, the display shows “CAL1/100%”.
   

4. Hold the dissolved oxygen probe in the air or place the sensor into the air-saturated water for 3 to 5 minutes, press ENTER key to confirm. Wait for the measured value to stabilize, the display shows “END”. Single point calibration is completed.

2 POINTS CALIBRATION:

1. Make sure that you have selected 2 points calibration in the setup menu.
2. Repeat the steps given above. When the first calibration point is done, the display shows “CAL2/0 ”. The meter prompts you to continue with second point calibration.
   
3. Dip the dissolved oxygen probe into the zero oxygen solution. Stir the sensor gently.
4. Press ENTER key to confirm. Wait for the measured value to stabilize, the display shows “END”. The meter returns to measurement mode automatically. Calibration is completed.

Temperature Calibration

During the measurement, if the temperature reading displayed differs from that of an accurate thermometer, you need to calibrate the meter.

1. Press the °C key to enter temperature calibration mode, the display shows current temperature reading.
   
2. Press▲ or ▼ key to set the temperature value.
3. Press ENTER key to confirm. Calibration is completed.

Measurement

This instrument is suitable for measuring the water, wastewater, brine and other liquids. If you use the meter to measure seawater or other water containing large amounts of salt, please set the salinity coefficient before use.

Some gas and steam such as chloride, sulphur dioxide, sulfureted hydrogen, ammonium, carbon dioxide and iodine can permeate the membrane via diffusion. So their existence will influence the measurement of dissolved oxygen.

If the sample contains solvent, grease, sulphide, and alga, the membrane on the probe will be blocked, damaged or eroded.

1. Press MEAS key to turn on the meter, wait for 15 minutes to polarize the probe.
2. If necessary, set the barometric pressure and salinity coefficient in the setup menu (Refer to “SETUP MENU” section).
3. Submerge probe in the sample solution, make sure the temperature sensor on the probe is fully immersed.
   
4. Stir the probe gently, wait for the reading to stabilize, record the measured value on the display.

Hold Function

The meter contains two data hold modes. When the Auto-Hold function is enabled, the meter will automatically sense a stable endpoint reading and freeze it, “HOLD” indicator appears on the display. If the Auto-Hold function is disabled, press  key, the meter will immediately freeze currently displayed value.

Press the key again to resume measuring.

DO Probe Care and Maintenance

• Please always keep probe’s membrane moist.
• If you do not use the dissolved oxygen probe for long periods, please screw off membrane cap and rinse the probe’s cathode, anode and the membrane with deionized water, then soak up residual water on them with filter paper, and install the probe.
  

Troubleshooting

Pressure VS Altitude Table

How to prepare the zero oxygen solution

Dissolve 500 mg of sodium sulphite reagent and a small amount of cobalt (II) chloride hexahydrate (CoCl2 ● 6H2O) in the 250 ml distilled water, mix the solution until reagent is completely dissolved