Shengaohua DOS-200 Benchtop Dissolved Oxygen Meter

Overview

The Shengaohua DOS-200 Benchtop Dissolved Oxygen Meter is a precision electrochemical instrument engineered for reliable, repeatable measurement of dissolved oxygen (DO) concentration in aqueous samples under controlled laboratory conditions. It employs a galvanic cell-type oxygen probe — a self-polarizing, zero-power-consumption sensor that generates a current proportional to the partial pressure of molecular oxygen diffusing through a gas-permeable membrane. This principle ensures stable baseline response, minimal drift, and no requirement for external polarization voltage — distinguishing it from polarographic sensors. The DOS-200 is calibrated using standard air-saturation or aqueous standard methods (e.g., Winkler titration traceable references), and integrates automatic temperature compensation across its full operational range (0.0–40.0 °C), correcting for both oxygen solubility variation and membrane diffusion kinetics. Designed for routine QC, environmental compliance testing, and method validation workflows, the instrument meets fundamental performance expectations aligned with ISO 5814:2012 (Water quality — Determination of dissolved oxygen — Electrochemical probe method) and supports data integrity requirements common in GLP and municipal water lab environments.

Key Features

• Galvanic cell DO probe with integrated thermistor for real-time temperature compensation
• Wide measurement range: 0–20 mg/L DO with 0.01 mg/L resolution and ±0.3 mg/L accuracy (at calibration temperature)
• Automatic saturation display mode (0–199%) for rapid field-referenced interpretation
• 4.3-inch high-contrast TFT LCD with intuitive icon-driven menu navigation and dual-parameter simultaneous display (DO + temperature)
• Built-in stability monitoring: drift ≤ ±0.10 mg/L over 3 hours confirms sensor and electronics integrity
• Robust benchtop architecture with EMI-shielded analog front-end and low-noise signal conditioning circuitry
• AC-powered operation (220 V, 50 Hz) optimized for fixed-lab deployment; no battery dependency or charging cycles

Sample Compatibility & Compliance

The DOS-200 is validated for use with freshwater, wastewater, effluent, process water, and buffered aqueous standards. It is not intended for highly viscous, suspended-solid-rich, or strongly oxidizing/reducing matrices without prior filtration or sample conditioning. Probe compatibility includes standard 12-mm diameter galvanic DO sensors with silicone or Teflon membranes. The instrument conforms to general electrical safety requirements per IEC 61010-1 for laboratory equipment. While not certified to FDA 21 CFR Part 11 out-of-the-box, its fixed calibration log (date/time-stamped manual entries) and non-editable measurement history support basic audit readiness for ISO/IEC 17025-accredited environmental labs conducting routine DO analysis per EPA Method 360.1 or ASTM D888.

Software & Data Management

The DOS-200 operates as a standalone benchtop analyzer with no embedded Bluetooth, USB, or PC interface. All measurements are displayed and retained only on-device; no internal memory or export functionality is provided. Users record results manually or integrate the instrument into broader LIMS workflows via external data entry. Calibration records — including date, temperature, reference value, and slope/membrane response — must be maintained separately in lab notebooks or electronic systems. For laboratories requiring automated data capture, third-party serial-to-USB adapters (RS-232 TTL level) may be used with custom scripting, though Shengaohua does not supply drivers or validation documentation for such configurations.

Applications

• Quality control of influent and effluent streams in municipal and industrial wastewater treatment plants
• Biochemical oxygen demand (BOD₅) incubation monitoring in environmental testing laboratories
• Process water DO verification in pharmaceutical clean steam condensate loops and bioreactor feed lines
• Educational demonstrations of oxygen solubility dependence on temperature, salinity, and atmospheric pressure
• Calibration verification of portable DO meters using stable, temperature-controlled reference solutions
• Research-level screening of aerobic microbial activity in soil leachates and sediment porewater extracts

FAQ

Does the DOS-200 support automatic barometric pressure compensation?

No. The instrument applies only temperature-based compensation. Users must manually adjust reported DO values using published oxygen solubility tables if operating at altitudes significantly above or below sea level.
Is the galvanic probe replaceable, and what is its typical service life?

Yes, the probe is a field-replaceable module. Under normal use (daily calibration, proper storage in moist sponge), membrane and electrolyte typically last 6–12 months before sensitivity decline exceeds ±0.3 mg/L tolerance.
Can the DOS-200 measure DO in seawater or high-salinity samples?

It can provide relative readings, but accuracy degrades above 5 g/L total dissolved solids due to ionic strength effects on membrane permeability and electrolyte conductivity. For marine applications, a dedicated salinity-compensated DO meter is recommended.
What maintenance procedures are required beyond daily calibration?

Weekly membrane cleaning with soft tissue, monthly electrolyte refill (if applicable to probe model), and annual verification against NIST-traceable DO standard solutions are advised for sustained metrological confidence.
Is technical documentation available in English?

Yes — an English-language user manual, calibration protocol guide, and ISO 5814 application note are supplied with each unit upon international shipment.