How to use a dissolved oxygen meter
Preparation before use of dissolved oxygen analyzer
1. Preliminary probe inspection
① Remove the red and black plastic caps as they are designed for shipping purposes and can be discarded.
② Soak the bottom of the probe 2.5cm in electrolyte to wet the sensor.
③ Gently shake the electrolyte to rinse the film, then fill it with clean electrolyte; Lightly tap the edge of the film with your fingertips to ensure there are no bubbles and to separate from water.
④ To avoid damaging the film, do not directly tap the bottom of the film.
⑤ Ensure that the rubber O-ring is accurately located inside the membrane cover.
⑥ Turn the membrane cover clockwise with the sensor facing downwards, and some electrolyte will overflow.
2. Calibration of dissolved oxygen analyzer
To achieve high accuracy, it is recommended to calibrate the instrument regularly. The calibration procedure for instrument standards typically consists of two values: 0.0% (zero) and 100% (slope). The instrument calibration is simple. Before calibration, it is necessary to ensure that the probe is installed correctly and completely, and that the probe is in a measurable state. Preliminary preparation: Pour a small amount of HI7040 zero oxygen solution into a beaker, and if possible, use a plastic beaker to reduce EMC interference. Ensure that electricity is measurable. Press the ON/OFF key to turn on the instrument. For calibration, it is recommended to wait for 15 minutes to adjust the power. Set the appropriate height coefficient and salinity coefficient to zero.
(1) Zero point calibration: ① Insert the electricity into HI7040 zero oxygen solution and gently stir for 2-3 minutes. ② Press the CAL key, and the "~" symbol and "NOT READY" symbol will flash until the reading stabilizes. ③ Once the reading stabilizes and the deviation is within the range, start flashing "CFM". Press the CFM key to confirm the "0.0%" reading. ④ Press the CAL key, and the instrument will return to measurement mode and record the zero point calibration data. (2) Slope calibration is recommended to be performed in air. Clean the battery with a large amount of clean water to remove any residual zero oxygen liquid on the battery Dry the battery and wait for a few minutes for the reading to stabilize. The "~" symbol and the "NOT READY" symbol will flash until the reading stabilizes Once the reading stabilizes, "CFM" starts flashing, press the "CFM" key to confirm "100.0%" D O. Value. ③ Once the reading is stable and within the deviation range. The instrument will save data (while adjusting the slope point), record zero calibration data, and return to measurement mode If the reading is not close to the selected value, the word "WRONG" will flash. If the reading exceeds the range, the word "WRONG" will flash simultaneously.
Guidelines for operating dissolved oxygen meters
1. DO measurement ensures that the instrument is calibrated, the protective cover is removed, and then the probe is immersed in the solution of the tested sample. Ensure that the temperature sensor is also immersed in the sample and wait for the reading to stabilize (about 1 minute). The dissolved oxygen value is displayed on the main screen, and the temperature is displayed on the lower screen. Press the RANGE key to convert values between ppm and saturation percentage.
2. The temperature measuring instrument is equipped with a built-in temperature probe. Before measurement, the probe should reach thermal equilibrium with the outside world, which may take a few minutes. The larger the temperature difference, the longer the required time.
① If "---" appears on the screen and the word "NO Probe" flashes, it indicates that the dissolved oxygen probe is connected incorrectly or the measured temperature exceeds the range. It is also possible that the probe is damaged.
② If the measured temperature exceeds the range, the word "℃" will flash.
③ If the reading exceeds the range, all range values may flash
④ Confirm that the instrument has been calibrated before measuring the sample
⑤ To successfully measure multiple samples and obtain readings, thoroughly clean the probe with deionized water before immersing it in the sample.
