The core working principle of a multi parameter water quality monitoring instrument is "sub parameter sensing and detection+signal conversion processing+data output integration". Different principle sensors are used to measure water quality indicators in a targeted manner, and then the data is processed uniformly. The specific steps are as follows:
1、 Core Logic: Parameter based Targeted Detection
The instrument is equipped with multiple independent sensors, each corresponding to a water quality parameter (such as pH, dissolved oxygen, turbidity, etc.), which capture parameter signals through dedicated detection principles without interfering with each other.
Sensors directly contact the water sample (or indirectly through a flow cell) and use physical, chemical, or electrochemical reactions to convert changes in water quality parameters into measurable electrical signals (such as voltage, current, resistance, optical signals, etc.).
The core is the "one parameter, one sensing mechanism" to ensure the detection accuracy and specificity of each indicator.
2、 Key links: signal conversion and data processing
Signal conversion: The raw electrical signal output by the sensor is weak and susceptible to interference. Through the built-in signal amplification module and filtering module of the instrument, the signal is amplified and noise is removed, and converted into a standard electrical signal (such as 4-20mA current signal, 0-5V voltage signal).
Data calibration and calculation: Combining the calibration curve stored inside the instrument (pre-set through standard solution calibration), convert the standard electrical signal into corresponding water quality parameter values (such as pH value, dissolved oxygen concentration mg/L).
Data integration: Summarize the measurement results of all parameters, display them in real-time on the screen, or upload them to the data platform through communication interfaces (RS485, Ethernet, etc.), while recording measurement time, operating conditions, and other information.
3、 Typical parameter detection principle (core sensing mechanism)
PH value: Using the glass electrode method, a potential difference related to pH value is generated when the electrode comes into contact with the water sample, and the pH value is converted by measuring the potential difference.
Dissolved oxygen: commonly used fluorescence method or Clark electrode method. Fluorescence method reflects oxygen concentration through the attenuation of fluorescence intensity, while electrode method generates current proportional to oxygen concentration through electrochemical oxidation-reduction reaction.
Turbidity: Using the principle of scattered light, suspended particles in water samples scatter incident light, and the turbidity value (NTU) is calculated by measuring the intensity of scattered light.
Conductivity: measures the conductivity of ions in a water sample, which is converted into conductivity values (μ S/cm) through changes in resistance between electrodes.
Nutrients such as ammonia nitrogen/total phosphorus: The electrode method or optical colorimetric method is used. The electrode method captures specific ion signals through ion selective electrodes, while the colorimetric method calculates values based on the relationship between the color intensity and concentration generated by chemical reactions.