The online explosion-proof pH meter is a precision measuring instrument designed specifically for flammable and explosive environments. Its core principle is based on the integration of electrochemical sensing and explosion-proof technology, achieving safe and accurate pH monitoring through the following mechanisms:
1、 Working principle: Electrochemical sensing and signal processing
Electrode system
Using a combination of glass electrodes and reference electrodes, the front end of the glass electrode is a special glass film (with a thickness of tens of microns) that can sense changes in hydrogen ion concentration in the solution and generate a potential difference; A reference electrode (such as a silver chloride electrode) provides a stable potential reference. The two constitute the primary battery, and their electromotive force is linearly related to the negative logarithm of hydrogen ion concentration (pH value), which conforms to the Nernst equation.
Signal conversion and amplification
The weak potential difference (in millivolts) generated by the electrodes is amplified by a high impedance transmitter (input impedance ≥ 1G Ω) and converted into a standard signal (such as a 4-20mA current loop or RS485 digital signal) for long-distance transmission to the monitoring system. Meanwhile, the built-in temperature sensor compensates for the real-time impact of temperature on pH measurement, ensuring an accuracy of ± 0.01pH.
Explosion proof signal transmission
The two-wire design synchronously transmits power and signals through the same cable, reducing wiring complexity; Adopting intrinsic safety circuits (such as ExiaICT4 certification), limiting circuit energy to<1.3W, ensuring that ignition sparks cannot be generated in explosive gas environments such as hydrogen.
2、 Security Design: Multi layer Protection Mechanism
Explosion proof enclosure and sealing structure
The shell is made of explosion-proof alloy steel or high-strength plastic, certified with IP65/IP67 protection level, which can withstand internal explosion pressure and prevent external gas from entering. All wiring interfaces use explosion-proof junction boxes and sealing rings to prevent the infiltration of flammable gases.
Non sparking operation and maintenance
Equipped with magnetic rod external calibration function, parameters can be adjusted without opening the cover, reducing the frequency of personnel entering the explosion-proof area; The integrated design of sensors and transmitters eliminates traditional junction boxes and eliminates the risk of electrical sparks caused by poor contact.
Fault warning and redundant protection
The self diagnostic system monitors the electrode status in real time (such as impedance, reference liquid remaining), and sends replacement warnings 30 days in advance; Supports HART protocol wireless communication, allowing remote modification of range or alarm threshold. In addition, the equipment has passed international explosion-proof certifications such as ATEX and IECEx, ensuring stable operation in environments ranging from -5 ℃ to 50 ℃.
3、 Application scenarios and advantages
Online explosion-proof pH meters are widely used in petroleum, chemical, pharmaceutical and other fields, such as:
Oilfield water injection monitoring: real-time measurement of pH value of sulfur-containing wastewater to prevent pipeline corrosion;
Pharmaceutical reaction control: Ensure that drug synthesis is carried out at a specific pH level to ensure product quality;
Hazardous waste treatment: Monitor the neutralization process of acidic wastewater to avoid secondary pollution.
Its advantages lie in:
High safety: Inherent safety design eliminates explosion hazards;
Convenient maintenance: Integrated structure reduces wiring and maintenance costs;
Reliable data: Automatic calibration and temperature compensation ensure long-term stability.
Through the deep integration of electrochemical sensing technology and explosion-proof engineering, online explosion-proof pH meters provide accurate and safe pH monitoring solutions for high-risk industrial environments.