1. Electrode-type pH Sensors
Electrode-type pH sensors are one of the most commonly used types. They consist of a glass electrode and a reference electrode. The glass electrode contains a glass membrane with high selectivity for hydrogen ions (H+) and an internal solution. The reference electrode is typically made of Ag/AgCl or calomel (HgCl2). When the sensor is immersed in the solution to be measured, the difference in hydrogen ion concentration across the glass membrane generates an potential difference (EMF), which is directly related to the pH value of the solution. By measuring this potential difference, the pH value of the solution can be determined.
Electrode-type pH sensors offer advantages such as accurate measurement and fast response, making them suitable for various industrial applications, such as wastewater treatment, electroplating wastewater, and fermentation processes. Furthermore, most electrode-type pH sensors have a temperature compensation system to ensure the accuracy of measurement results at different temperatures.
2. Fiber Optic pH Sensors
Fiber optic pH sensors use an optical method to measure pH values. They consist of a light source, a fiber optic transmission unit, and a pH-sensitive fluorescent material. When light shines on a fluorescent material, the material emits a pH-related light signal. This signal is transmitted to a detector via an optical fiber transmission unit for measurement, thus determining the solution's pH value.
The advantages of fiber optic pH sensors include strong anti-interference capabilities, good adaptability to harsh environments, and remote monitoring capabilities. These characteristics make fiber optic pH sensors highly advantageous in industrial scenarios requiring remote measurement or monitoring.
3. Integrated Sensors
Integrated sensors integrate the pH sensing element and signal processing circuitry onto a single chip. These sensors offer advantages such as small size, high accuracy, fast response, and ease of automation. However, due to their high degree of integration, manufacturing costs are relatively high. Integrated sensors are widely used in industrial automation systems, especially in scenarios requiring high accuracy and rapid response.
4. Current-Type pH Sensors
Current-type pH sensors are a special type of industrial online pH sensor whose output signal is a current signal (e.g., DC 4~20mA). These sensors typically offer high measurement accuracy and stability, making them suitable for industrial scenarios requiring remote transmission and processing. Current-type pH sensors play a crucial role in industrial automation control systems, enabling real-time monitoring and adjustment of solution pH values.
5. Industrial-Grade pH Sensors
Industrial-grade pH sensors are designed for industrial environments, offering high durability and stability. They typically have a long service life and low maintenance costs, and can withstand various harsh industrial environments. Industrial-grade pH sensors are widely used in water quality monitoring, food processing, chemical production, and other fields, providing reliable assurance for industrial production processes.