ZL-DO7011 Membrane type dissolved oxygen sensor is the measure of oxygen dissolved in an aqueous solution. Polarographic measurement principle, the dissolution value depends on the temperature of the aqueous solution, pressure and salinity in solution.
Product Introduction
The most common type of membrane DO sensor operates on the Clark Cell principle, which involves an electrochemical reaction. The core components are:
-
Sensor Body: Houses the internal elements.
-
Cathode: A small disc of a precious metal, typically Gold or Platinum.
-
Anode: Usually made of Silver (Ag).
-
Electrolyte Solution: A KCl (Potassium Chloride) solution that fills the sensor body, completing the internal electrical circuit.
-
Permeable Membrane: A thin, selective membrane (made of Teflon, PE, or similar material) that stretches over the cathode and anode, separating them from the sample fluid. This is the most critical component.
The working process involves diffusion and reduction:
-
Diffusion: Dissolved oxygen molecules (O₂) from the sample fluid diffuse through the permeable membrane at a rate proportional to the oxygen partial pressure in the sample.
-
Electrochemical Reduction: Once inside, the O₂ molecules reach the cathode, where they are electrochemically reduced.
-
At the Cathode: O₂ + 2H₂O + 4e⁻ → 4OH⁻
-
(Oxygen is reduced by electrons, producing hydroxide ions).
-
-
Completion of Circuit: This reduction reaction consumes electrons, creating a potential that drives a corresponding oxidation reaction at the anode.
-
At the Anode: 4Ag + 4Cl⁻ → 4AgCl + 4e⁻
-
(Silver is oxidized, releasing electrons and forming a silver chloride layer).
-
-
Current Generation: The flow of electrons (current) from the anode to the cathode is directly proportional to the rate of oxygen reduction. Since the diffusion rate is constant (controlled by the membrane), this electrical current is directly proportional to the dissolved oxygen concentration in the sample fluid.
-
Measurement: The meter measures this tiny current, amplifies it, and converts it into a DO reading (typically in mg/L or % saturation).
Product Advantages
Application Field
1. Wastewater Treatment Plants
-
Purpose: To monitor and control the activated sludge process in aeration basins.
-
Why Used: Optimal DO levels (~1-3 mg/L) are crucial for aerobic bacteria to efficiently break down organic waste. Precise DO control ensures effective treatment while minimizing the massive energy cost of over-aeration.
2. Aquaculture & Fish Farming
-
Purpose: To maintain healthy oxygen levels in fish tanks, ponds, and transport units.
-
Why Used: Oxygen is vital for fish survival, growth, and health. Low DO levels (hypoxia) cause stress, disease, and mass mortality. Continuous monitoring allows for automatic activation of aerators.
3. Pharmaceutical & Biotechnology Fermentation
-
Purpose: To precisely control oxygen levels in bioreactors and fermenters during cell culture and fermentation processes.
-
Why Used: Many microorganisms (bacteria, yeast) used to produce antibiotics, vaccines, and enzymes require specific,This is a critical process parameter (CPP).
4. Environmental Monitoring & Research
-
Purpose: To assess the health of rivers, lakes, and oceans by measuring DO levels in the water column.
-
Why Used: DO is a primary indicator of water quality and ecosystem health. Low DO can indicate pollution (e.g., from nutrient runoff causing algal blooms and eutrophication). Scientists use profilers with DO sensors to study hypoxia and its impact on aquatic life.
Technical Parameter
| Model | ZL-DO7011 |
| Measure range | DO: 0-20 mg/L, 0.6 MPa； Temperature: 0-60℃ |
| Accuracy | DO: ±3% of the measured value； Temperature: ±0.5℃ |
| Temperature Type | NTC 10k/PT1000/2.252K |
| Output Type | 4-20mA output |
| Weight | 1.85Kg |
| Cable length | Standard:10m, the maximum may be extended to 100m |
