The correct selection of an online pH controller requires comprehensive consideration from three aspects: core parameters, functional requirements, and practical application scenarios. The following is a guide for selecting key parameters and functions:
1、 Core parameters
Measurement range and accuracy: The measurement range should cover the actual requirements (such as 0-14PH), and the accuracy should meet the process requirements. For high-precision scenarios such as laboratories and biopharmaceuticals, equipment with a resolution of 0.01pH and an accuracy of ± 0.02pH should be selected; The general industrial scenario can accept ± 0.1pH.
Temperature compensation: Temperature changes can affect pH measurement results, and a controller that supports automatic temperature compensation (ATC) should be selected. The compensation range should cover actual operating conditions (such as 0-99.9 ℃), and the reference temperature is usually 25 ℃.
Stability and repeatability: The lower the stability (such as ± 0.02pH/24h) and repeatability error (such as ± 0.02pH), the more reliable the measurement results, making it suitable for scenarios that require high data consistency.
Input impedance: High input impedance (≥ 10 ¹² Ω) can reduce interference to the measurement circuit and ensure data accuracy.
2、 Functional requirements
Multi parameter display: Priority should be given to devices that support displaying multiple parameters such as pH value, temperature, time, and output current on the same screen for real-time monitoring and data analysis.
Data storage and transmission: Equipped with historical curve storage (such as continuous recording of data for one month) and RS485 communication interface, it can achieve remote data transmission and analysis, suitable for scenarios that require long-term monitoring.
Automatic cleaning and calibration: Equipped with automatic cleaning function (such as ultrasonic cleaning) and multiple calibration methods (such as manual input of zero point, slope or known pH value calibration), it can reduce manual maintenance costs and improve measurement stability.
Alarm and Control Output: Supports high and low point alarm relay output (such as AC220V, 3A) and 4-20mA current output, which can achieve automatic pH control and is suitable for scenarios that require linkage with dosing devices.
3、 Actual application scenarios
Industrial wastewater treatment: High protection level (such as IP65) and corrosion-resistant equipment should be selected, and self-cleaning devices should be equipped to cope with complex water quality environments.
Laboratory and Biopharmaceutical: High precision and high stability equipment should be selected, and support multi parameter display and data storage to meet strict quality control requirements.
Thermal power and chemical industry: It is necessary to choose equipment that supports high temperature and high pressure measurement and has a 25 ℃ conversion function to adapt to special working conditions.