E-mail: michael@shboqu.com   |   Expert in Water Quality Measurement and Water Treatment Project

In-depth analysis of the use principle of turbidimeter

by:BOQU     2023-03-18
The optical system of the nephelometer consists of a tungsten lamp, a 90° detector for monitoring scattered light, and a transmitted light detector. The instrument microprocessor can calculate the ratio of the signals from the 90° detector and the transmitted light detector. This ratio calculation technique corrects for interference due to colorimetric and/or light-absorbing substances (such as activated carbon) and compensates for effects due to fluctuations in light intensity, providing long-term calibration stability. The optical system is also designed to reduce drift light and improve test accuracy. Turbidity is the performance of suspended matter in water to hinder the degree of light passing through. Suspended solids and colloids such as soil, dust, fine organic matter, zooplankton and other microorganisms in the water can cause turbidity in the water. The turbidimeter adopts the principle of 90° scattered light. When the parallel light beam emitted by the light source passes through the solution, part of it is absorbed and scattered, and the other part passes through the solution. The scattered light intensity at 90° to the incident light conforms to the Rayleigh formula: Is=((KNV2)I0 where: I0—incident light intensity Is—scattered light intensity N—particle number per unit solution, V—particle volume ——Wavelength of incident light K——coefficient, under the condition of constant incident light, within a certain range of turbidity, the intensity of scattered light is proportional to the turbidity of the solution. The above formula can be expressed as: Is/I0=KN (K is a constant ), according to this formula, the turbidity of the water sample can be measured by measuring the scattered light intensity of the particles in the water sample. The measurement principle of the turbidimeter: the turbidity is the degree of obstruction of the suspended matter in the water to the light passing through. The water contains soil, dust, fine organic matter and other microorganisms and colloids, which can cause turbidity in the water. After the light waves sent by the transmitter on the sensor are absorbed, reflected and scattered by the measured object during transmission, some of the transmitted light can be irradiated On the detector in the direction of 180°, a part of the scattered light is scattered on the detector in the direction of 90°. The light intensity received by the detector in the direction of 180° and 90° has a certain relationship with the turbidity of the measured sewage. Therefore, the turbidity of sewage can be calculated by measuring the intensity of transmitted light and scattered light. Product features: 1. The turbidity sensor adopts surface scattering, the light source part and the photoelectric detection part are free of cleaning, and the reading is accurate. 2. The light source adopts laser light source , stable light source, low power consumption, energy saving and environmental protection. 3. The turbidity transmitter is composed of an electronic unit and a measurement unit. The product has the characteristics of free calibration, high precision, and low power consumption. 4. It has upper and lower limit alarm functions, and has Two-way relay output control, adjustable return difference. 5. It has two display modes: digital display and waveform display. The digital display mode has upper and lower limit alarm display and time and date display. The waveform display mode can be automatically adjusted according to the upper and lower limit alarm values Display range. 6. The value of the offset b can be adjusted according to the formula y=kx+b, and the positive or negative of the offset can be adjusted, and the analog output 4-20mA standard signal. 7. It has the function of waveform recording, which can continuously record two Month (60) days of waveform data, you can look at the historical data. 8. In addition to the transmission function, the transmitter also has an isolation function. The input and output signals of the sensor are isolated by a linear optocoupler circuit to effectively ensure the signal stability.
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