Dissolved Oxygen Electrode

Introduction to Dissolved Oxygen Electrode Utilizing a polarographic electrode, the anode is made of Ag/AgCl and the cathode of platinum (Pt), with a special electrolyte solution filled between them. The electrode is encapsulated by a silicone rubber permeable membrane. During measurement, a polarization voltage of 675 mV is applied between the electrodes. Oxygen permeates through the membrane and is consumed at the cathode, while an equivalent amount of oxygen is generated at the anode. This dynamic process continues until the oxygen partial pressures on both sides reach equilibrium. At this point, the current between the electrodes is proportional to the oxygen partial pressure. The secondary meter detects this current and, through a series of conversions, obtains the oxygen concentration and content. Simultaneously, an NTC (Negative Temperature Coefficient thermistor) detects the temperature of the measured liquid. The secondary meter samples the data and performs temperature compensation, converting the oxygen concentration or content to values at 25°C. Cathode reaction: O₂ + 2H₂O + 4e⁻ → 4OH⁻ Anode reaction: 4Ag + 4Cl⁻ → 4AgCl + 4e⁻ Applications Dissolved oxygen electrodes can be used to monitor processes where oxygen content affects reaction speed, process efficiency, or the environment, such as in aquaculture, bioreactions, environmental testing (lakes, streams, oceans), water/wastewater treatment, and wine production. The T401ppm dissolved oxygen electrode offers high stability and reliability, suitable for use in harsh environments with minimal maintenance. Troubleshooting When using polarographic electrodes, preheat for at least 15–30 minutes before calibration or measurement. To ensure no bubbles are present in the electrolyte of the membrane, the ASI membrane cap is designed to expel all air from the liquid chamber when installing the membrane head. No bubbles should remain on the membrane surface, as they may be misinterpreted as oxygen-saturated samples. Even when using instruments with automatic temperature compensation, calibrate the electrode at a temperature close to that of the sample solution. Calibrate the electrode in air, using air as the 100% saturated dissolved oxygen reference point. Since the electrode consumes oxygen, the oxygen concentration at the probe surface momentarily decreases. Therefore, it is essential to stir the solution during measurement. Replace the membrane if it is damaged. Technical Parameters: Measurement range: 0–20 mg/L (ppm), 0–200% Operating temperature: 0–130°C Temperature compensation range: 0–130°C Measurement principle: Amperometric sensor Membrane thickness: 50 µm Electrode material: UPVC or 316L Sensing material: POM outer tube, silver tube, gold wire with temperature compensation function Response time: 90% in 60 seconds (upscale, at 20°C) Polarization time: 2 hours Minimum flow rate: 2.5 cm/s Cable length: Standard 10 m Installation method: 3/4-inch pipe thread installation Standard configuration: One electrode, two spare membrane heads, one bottle of specialized electrolyte solution.