Online Dissolved oxygen analyzers can be divided into three forms according to the principle, namely: primary battery type, polarographic type, and fluorescence method. Today we will introduce the battery Type and fluorescence method, we can compare them from the following aspects.
- Working principles of dissolved oxygen analyzer:
(1).The working principle of the primary battery type dissolved oxygen online analyzer:
There are two electrodes made of different metals immersed in the filled solution. In this way, a natural electrochemical reaction occurs between the two electrodes. The oxygen dissolved in the water will enter the electrolyte in the electrode through the semi-permeable membrane on the electrode head. Incoming oxygen molecules are reduced to hydroxide near the cathode. (For every oxygen molecule reduced, 4 electrons are released from the anode) This creates a current at the anode proportional to the number of electrons. The resulting current (or voltage) is proportional to the concentration of dissolved oxygen entering the electrode system.
(2). The working principle of the fluorescent dissolved oxygen online analyzer:
The fluorescence dissolved oxygen meter is based on the principle of fluorescence quenching. The blue light irradiates the fluorescent material to excite the fluorescent material and emit red light. Since oxygen molecules can take away energy (quenching effect), the time and intensity of the excited red light are inversely proportional to the concentration of oxygen molecules. By measuring the phase difference between the excitation red light and the reference light and comparing it with the internal calibration value, the concentration of oxygen molecules can be calculated.
- Dissolved oxygen online analyzer electrode composition:
Electrode composition of primary cell type dissolved oxygen online analyzer: zinc anode; silver cathode, covered with semi-permeable membrane; electrolyte;
Electrode composition of fluorescent dissolved oxygen online analyzer: sensor, optical element, electronic element, probe.
- Comparison of application scope of dissolved oxygen online analyzer:
Primary battery type dissolved oxygen online analyzer application range:
wide application range, can measure ppb trace level and ppm level;
Scope of application of fluorescence dissolved oxygen analyzer:
Since the optical dissolved oxygen analyzer adopts a nonlinear calculation method (the fluorescence quenching time interval and dissolved oxygen concentration have a nonlinear relationship), only single-point verification and process calibration can be performed; it is recommended to use measurement The range is 0.05-20mg/L.
- Contrast of use conditions of dissolved oxygen online analyzer:
The use conditions of the primary battery type dissolved oxygen online analyzer are limited:
the signal-to-noise ratio is small, and the possibility of generating false signals increases; there is a minimum flow rate requirement for the measurement medium;
Restrictions on the use conditions of the fluorescent dissolved oxygen online analyzer:
there is no minimum flow rate requirement for the measurement medium.
- Comparison of interference factors of three dissolved oxygen online analyzers:
Interference factors of primary battery type dissolved oxygen online analyzer:
PH, medium conductivity, oil, sulfide, iron, ferrous, carbonate and algae in the medium; if the electrolyte is polluted, it will cause the battery potential to decrease. Drift, resulting in measurement errors;
Interference factors of fluorescent dissolved oxygen online analyzer:
strong anti-interference ability, in addition to high concentration of chlorine dioxide, it is not easy to be affected by other interfering substances, but the probe should avoid direct sunlight; the fluorescent cap is scratched or partially polluted It retains its accuracy in any condition and is easy to clean.
- Comparison of maintenance amount of dissolved oxygen online analyzers:
Primary battery type dissolved oxygen online analyzer maintenance: good electrodes need to replenish electrolyte and replace diaphragms, clean electrodes and other maintenance for about half a year;
Maintenance amount of fluorescent dissolved oxygen online analyzer: low maintenance amount, no need to calibrate, replace electrolyte and permeable membrane, replace fluorescent cap every 2~3 years.
To sum up, it is recommended to choose a fluorescent dissolved oxygen online analyzer on site, which is not only easy to use, but also convenient. Desun Uniwill supplies fluorescent dissolved oxygen sensor, portable dissolved oxygen meter with factory price!
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