For ozone air testers, it is a must-have product for many companies. So for consumers who are not in the industry of gas detectors, do you really understand ozone air testers? First let’s take a comprehensive look at what is the technology used by ozone air tester?
l Basic structure of ozone air tester
l Circuit principle of ozone air tester
l Techniques applied by other types of ozone air testers
The ozone air tester is mainly composed of low-pressure ultraviolet lamp, light wave filter, incident ultraviolet light reflector, ozone absorption cell, sample photoelectric sensor, sample photoelectric sensor, output display, and circuit components.
The basic circuit is composed of six parts: power supply, UV lamp control, UV light sample detection, UV light sample detection, logarithmic amplifier Log100, analog output and display.
The core part of the circuit is to use the logarithmic amplifier Log100 to realize the mathematical model of ozone concentration. LOG100 is a 14-pin integrated circuit that can perform logarithmic operation on the ratio of two currents or voltages. The amplifier has a wide output current dynamic range, which can vary from 1nA to 1mA. The output error range does not exceed 0.1%. Basic wiring, output formula: Vout =VT×ln I0/I (Note: VT—constant; Vout—output voltage).
The power supply part mainly generates the high-voltage power supply required by the ultraviolet lamp, and at the same time generates the +15V DC power required on the circuit board. The lamp control part of the UV lamp is mainly to control the UV lamp current within a constant allowable range. If it is too high or too low, it can be automatically adjusted. If it cannot be adjusted, it means that the life of the UV lamp has expired. A red light on the panel turns on, prompting you to replace it with a new one. Of the UV lamp. The standard ultraviolet light detection and sampling ultraviolet light detection part is also a more critical part. The photoelectric sensor converts the ultraviolet light signal into a voltage signal, and then the signal is processed and amplified by the operational amplifier twice, and then sent to the LOG100 for calculation and processing, and then displayed and output. The analog output 0~20mA is linearly related to the ozone concentration.
1. Semiconductor ozone air tester use gas-sensitive semiconductor materials, such as WO3, Sn0, In203, and other sensitive elements made of oxides. When they absorb ozone, redox reactions occur, generating or releasing heat, causing the temperature of the element to change accordingly, thus The resistance changes, the ozone concentration is converted into an electrical signal, and the ozone concentration is measured. In general, with the increase of the concentration, the resistance of the component increases significantly, and it is linear in a certain range.
2. The electrochemical ozone air tester is composed of working electrode, counter electrode, participating electrode, electrolyte and circuit system. A constant potential value can be maintained between the working electrode and the participating electrodes. When ozone diffuses into the sensor, a reduction reaction occurs at the working electrode, an oxidation reaction occurs at the counter electrode, and a tiny current flows between the electricity price and the working electrode. The ozone air tester is proportional to a certain range, and finally processed by the circuit system to calculate the ozone content.
The ozone air tester adopts the ultraviolet absorption method, single point light source, dual light path detection, small size, high accuracy, good stability, and can work continuously; its measurement range is wide, and the maximum measurement range is 300 O3 g/m. In addition, the detector also has 0/4-20 mA analog output, which can be combined with ozone generator and PID regulator to form an ozone closed-loop automatic control system.
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