DO700 Dissolved Oxygen Controller, Optical DO, Saturation, and Oxygen Partial Pressure Measurement
Introduction
The DO700 dissolved oxygen controller utilizes a fluorescence-based optical sensing principle in which the sensor tip is coated with a luminescent material. A blue LED light source excites this material, causing it to emit red fluorescence. The decay time and intensity of the red light are inversely related to the concentration of dissolved oxygen molecules in the medium. Because this optical method does not deplete oxygen during measurement, it delivers stable, reliable data with minimal maintenance requirements.
This dissolved oxygen meter supports multiple output interfaces, including 4–20 mA analog signals, relay outputs, and RS485 digital communication (Modbus-RTU), enabling seamless integration with PLCs and automation systems. Standard calibration options, such as automatic air calibration and sample calibration, further simplify setup and ensure dependable long-term operation.
Working principle
The measurement process of the DO700 dissolved oxygen controller can be understood in three essential stages:
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Optical excitation: The internal blue LED source illuminates the luminescent coating on the sensor cap. This coating is responsive to oxygen and emits red fluorescent light when excited.
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Oxygen interaction: Dissolved oxygen molecules in the liquid interact with the luminescent layer, causing quenching (a reduction in fluorescence intensity) and decay time. The degree of quenching reflects the dissolved oxygen concentration.
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Signal processing and output: The optical response is captured and converted into electrical signals. These signals are processed to calculate DO levels and temperature, which are then displayed and transmitted through analog and digital outputs for monitoring or control.
Key features
The key capabilities of the DO700 optical dissolved oxygen meter are summarized below:
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Optical fluorescence measuring: Uses blue LED excitation and luminescent coating to measure dissolved oxygen based on changes in emitted light decay and intensity. This method avoids oxygen consumption during measurement and enhances data stability.
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Wide Measurement Range: Designed to monitor DO concentration from 0 to 20 mg/L (or ppm), covering typical requirements in environmental and industrial applications.
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High Resolution and Accuracy: Offers fine measurement resolution with accuracy suitable for quality control and process monitoring.
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Multiple Output Interfaces: Includes isolated 4–20 mA analog outputs, multiple relay contacts for control functions, and RS485 digital communication (Modbus-RTU) for integration with distributed monitoring systems.
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Flexible Calibration: Supports automatic air calibration and sample calibration to suit different measurement scenarios.
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Robust Construction: Built with corrosion-resistant materials such as SUS316L stainless steel and optional titanium alloy for marine use, and equipped with fluorine rubber O-rings and PVC cabling for durability.
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User-Friendly Display and Operation: Features a dot-matrix LCD with LED backlight for clear on-site display of DO and temperature data.
Specification
| Product | Dissolved oxygen meter |
| Model | DO700 |
| Measure range | 0-20mg/L,0-20ppm,0-45deg C |
| Accuracy | Resolution:±3%, Temperature: ±0.5℃ |
| Pressure range | ≤0.3Mpa |
| Calibration | Automatic air calibration, Sample calibration |
| Sensor material | SUS316L+PVC (Ordinary Version), |
| Titanium Alloy (Seawater Version) | |
| O-ring: Fluoro-rubber; Cable: PVC | |
| Cable length | Standard 10-Meter Cable, Max: 100m |
| Display | 128 * 64 dot matrix LCD with LED backlight |
| Output | 4-20mA(Max three-way); |
| RS485 MODBUS; | |
| Rlay output(Max three-way); | |
| Power supply | AC220V, 50Hz,(optional 24V） |
Applications
The DO700 Optical Dissolved Oxygen Meter is suitable for continuous online DO monitoring in a wide range of scenarios where dissolved oxygen is a critical parameter:
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Wastewater Treatment Plants: Used to regulate oxygen levels in aeration basins and monitor effluent quality as part of biological water treatment processes.
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Water Works & Drinking Water Systems: Supports oxygen enrichment, corrosion protection, and overall water quality monitoring in drinking water facilities.
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Environmental Monitoring: Continuous DO measurement in rivers, lakes, reservoirs, and other surface waters helps assess ecological conditions and regulatory compliance.
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Industrial Process Control: Monitors oxygen in process water streams across utilities and industrial facilities to support efficient operation and prevent corrosion or scaling.
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Aquaculture: Ensures optimal dissolved oxygen levels for fish and aquatic organism health and growth.
