YSI Model 58 Digital Dissolved Oxygen Meter
| Origin | USA |
|---|---|
| Manufacturer Type | Authorized Distributor |
| Origin Category | Imported |
| Model | YSI Model 58 |
| Price | Upon Request |
Overview
The YSI Model 58 Digital Dissolved Oxygen Meter is a field-proven, bench-and-field portable instrument engineered for high-reliability dissolved oxygen (DO) measurement in freshwater, estuarine, and marine environments. It operates on the Clark-type polarographic principle—utilizing a gold cathode and silver/silver chloride anode within a gas-permeable membrane, where oxygen diffusion generates a current proportional to DO concentration. This electrochemical method delivers stable, reproducible readings across variable salinity and temperature conditions without requiring frequent recalibration. Designed for rigorous environmental monitoring applications—including wastewater treatment plant effluent verification, limnological surveys, aquaculture management, and regulatory compliance sampling—the Model 58 maintains consistent performance under demanding operational constraints, including low-light field conditions and extended battery-powered deployment.
Key Features
- Simultaneous dual-mode display: mg/L (ppm) and % air saturation—enabling rapid interpretation of biological oxygen demand context or saturation anomalies
- Integrated automatic temperature compensation (0–45°C), correcting for both membrane permeability drift and oxygen solubility variation per ISO 5814:2012
- Direct salinity input (0–40 ppt) with built-in temperature-compensated correction algorithm, supporting accurate DO quantification in brackish and seawater per ASTM D888-22
- Backlit LCD display with 0.1 mg/L / 0.1% resolution—optimized for readability in shaded or nocturnal field settings
- Robust, sealed housing rated IP67 for temporary submersion and resistance to dust, humidity, and splash exposure
- Dual power options: four “D” cell batteries (1,000-hour typical life with carbon-zinc cells) or optional AC adapter; low-battery indicator and dedicated battery-check button
- Onboard stirrer power bay accommodates auxiliary battery pack for integrated magnetic stirring during stationary measurements
- Analog recorder output (0–1 V full scale, ±0.4% FS accuracy) compatible with strip-chart recorders, data loggers, and SCADA interfaces
Sample Compatibility & Compliance
The YSI Model 58 is validated for use with standard Clark-type DO probes (e.g., YSI 5739, 5742) and supports direct immersion in natural waters, activated sludge, sediment pore water (with appropriate probe shielding), and process streams. Its measurement range (0–20 mg/L DO; 0–200% air saturation) accommodates hypoxic, normoxic, and supersaturated conditions—critical for evaluating photosynthetic oxygen production or nitrogen stripping efficiency. The instrument complies with foundational methodology standards referenced in EPA Method 360.1, APHA Standard Methods 4500-O G, and ISO 5814:2012. While not inherently 21 CFR Part 11 compliant (as it lacks electronic audit trails), its analog output and manual calibration logs support GLP-aligned documentation when used within validated laboratory or field SOPs.
Software & Data Management
The Model 58 is a standalone analog/digital hybrid instrument with no embedded firmware-based data storage or wireless connectivity. All measurements are recorded manually or captured externally via its 0–1 V analog output. Users integrate it into larger data acquisition ecosystems using third-party analog-to-digital converters (e.g., Campbell Scientific CR1000X, HOBO U12-008). Calibration records—including zero-point and span values, temperature, salinity, and atmospheric pressure (if manually entered)—must be maintained per site-specific QA/QC protocols. For laboratories operating under ISO/IEC 17025 or NELAC requirements, traceable calibration certificates for associated electrodes and thermistors are recommended at six-month intervals.
Applications
- Regulatory wastewater discharge monitoring per NPDES permit requirements
- In-situ profiling of stratified lakes and reservoirs to assess hypolimnetic oxygen depletion
- Aquaculture pond management—optimizing aeration cycles based on real-time DO trends
- Bioreactor and activated sludge process control in municipal and industrial treatment facilities
- Field validation of optical DO sensors and multi-parameter sondes
- Educational laboratory instruction in environmental chemistry and aquatic ecology
FAQ
Does the YSI Model 58 support automatic barometric pressure compensation?
No—barometric pressure must be entered manually during calibration if absolute DO (mg/L) accuracy is required. Air saturation mode eliminates this dependency.
Can the instrument measure DO in viscous or particulate-laden samples?
Yes, provided the Clark electrode is equipped with a protective guard and stirred at consistent speed (e.g., using the optional YSI 58-stirrer module) to maintain laminar diffusion layer stability.
What is the recommended calibration frequency?
Daily field use requires zero and span calibration before first measurement; weekly lab use warrants calibration prior to each session. Electrode membrane replacement is advised every 2–4 weeks under continuous operation.
Is the recorder output isolated or grounded?
The 0–1 V output is non-isolated and referenced to the instrument’s common ground. Use of differential-input data loggers is recommended to minimize ground-loop interference.
Does the Model 58 meet CE or RoHS directives?
As a legacy instrument originally manufactured in the 1990s, the Model 58 predates mandatory CE marking for environmental instrumentation. RoHS compliance applies only to post-2006 service replacements and accessories.
