OHAUS STARTER 300D Portable Dissolved Oxygen Meter

Overview

The OHAUS STARTER 300D Portable Dissolved Oxygen Meter is an electrochemical field instrument engineered for rapid, reliable measurement of dissolved oxygen (DO) concentration and temperature in aqueous environments. It employs a galvanic cell (Clark-type) sensor principle—where molecular oxygen diffuses through a gas-permeable membrane and undergoes reduction at a cathode, generating a current linearly proportional to DO partial pressure. This analog signal is digitized and compensated for temperature (via integrated NTC thermistor) and atmospheric pressure (user-input or barometric sensor–enabled models), delivering results in mg/L (ppm) or % saturation with traceable accuracy. Designed for routine environmental monitoring, wastewater operations, aquaculture management, and field-based water quality surveys, the STARTER 300D meets core functional requirements defined in ISO 5814:2012 (Water quality — Determination of dissolved oxygen — Electrochemical probe method) and aligns with EPA Method 360.1 for field DO analysis.

Key Features

• Instant operation—no warm-up time required; ready for measurement within 5 seconds of power-on.
• High-contrast backlit LCD display presenting simultaneous readings of DO (mg/L and % sat), temperature (°C), and electrode status indicators (e.g., membrane integrity, electrolyte level).
• Ergonomic, IP67-rated industrial housing with rubberized grip and sealed keypad—designed for durability in humid, dusty, or splash-prone outdoor conditions.
• Auto-ranging measurement capability covering 0.00–20.00 mg/L DO and 0.0–50.0 °C temperature range, with resolution of 0.01 mg/L and 0.1 °C respectively.
• One-point or two-point calibration protocol supported via air-saturated water or zero-oxygen solution (sodium sulfite), with on-screen step-by-step guidance and calibration slope validation.
• Built-in data logging (up to 500 records) with timestamp and manual/auto-save options, exportable via USB interface to CSV-compatible software.

Sample Compatibility & Compliance

The STARTER 300D is validated for use with freshwater, seawater (with salinity compensation up to 45 ppt), wastewater effluents, and process streams exhibiting turbidity ≤ 500 NTU and suspended solids ≤ 100 mg/L. Sensor compatibility includes standard 12-mm diameter galvanic DO probes with replaceable membranes and refillable electrolyte (KCl-based). The instrument complies with CE marking directives (2014/30/EU EMC and 2014/35/EU LVD), RoHS 2011/65/EU, and supports GLP-compliant workflows through user ID assignment, calibration history storage, and audit-ready event logs. While not FDA 21 CFR Part 11–certified out-of-the-box, its data export architecture enables integration into validated laboratory information management systems (LIMS) for regulated environments.

Software & Data Management

Data transfer is facilitated via micro-USB connection to Windows/macOS platforms using OHAUS’ free STARTER PC Utility software. This application enables batch download, graphical trend visualization (DO vs. time/temperature), statistical summary (mean, SD, min/max), and PDF report generation with embedded instrument ID, operator name, calibration date, and environmental metadata. All stored measurements retain firmware-tracked timestamps and are tagged with calibration verification flags—ensuring traceability across sampling campaigns. Firmware updates are delivered via the same utility, supporting long-term device maintainability and regulatory adaptability.

Applications

• Field-based assessment of surface water bodies (rivers, lakes, reservoirs) for ecological health monitoring per national water quality standards (e.g., China’s GB 3838-2002, US EPA Clean Water Act criteria).
• Real-time DO profiling during activated sludge process control in municipal and industrial wastewater treatment plants.
• Aquaculture site management—including pond aeration scheduling, feed optimization, and stress indicator tracking in shrimp, tilapia, and salmonid farming operations.
• Educational laboratories requiring robust, entry-level instrumentation for teaching principles of aquatic chemistry, respiration kinetics, and sensor electrochemistry.
• Environmental consulting and third-party compliance verification where portable, battery-operated DO verification is mandated by project scope or regulatory sampling plans.

FAQ

Does the STARTER 300D support automatic atmospheric pressure compensation?
Yes—when connected to an optional external barometric pressure sensor (OHAUS BP-S1), the meter applies real-time pressure correction; otherwise, manual input (in hPa or mmHg) is accepted during setup.
Can the device store calibration data separately for multiple probes?
No—calibration parameters are stored globally per instrument; probe-specific offsets require manual documentation or external LIMS linkage.
What is the battery life under continuous use?
With alkaline AA batteries, typical operation exceeds 200 hours; lithium AA batteries extend this to ~300 hours, with low-battery warning displayed at <10% capacity.
Is the sensor cable detachable for replacement or length extension?
Yes—the standard 1.5 m coiled cable uses a waterproof M12 connector, enabling field-swappable cables up to 10 m without signal degradation.
How often should the DO membrane and electrolyte be replaced?
Recommended every 2–3 months under daily field use, or immediately following exposure to oils, surfactants, or high-sulfide waters—per OHAUS Technical Bulletin TB-DO-02.