OHAUS ST302 pH Electrode
| Brand | OHAUS |
|---|---|
| Origin | Jiangsu, China |
| Manufacturer Type | Original Equipment Manufacturer (OEM) |
| Product Category | Domestic |
| Model | ST302 |
| Price | Upon Request |
| pH Range | 0.00–14.00 |
| Cable Length | 1.1 m |
| Electrode Body Material | Plastic |
| Dimensions (L × Ø) | 120 mm × 12 mm |
| Net Weight | 80 g |
| Temperature Range | 0 °C to 80 °C |
| Integrated Temperature Sensor | 30 kΩ NTC thermistor |
| Part Number | 31041063 |
Overview
The OHAUS ST302 pH Electrode is a robust, general-purpose combination pH electrode engineered for reliable and reproducible potentiometric measurements in routine laboratory, educational, and quality control environments. It operates on the principle of hydrogen ion activity detection via a glass membrane sensing element coupled with an integrated Ag/AgCl reference system and a built-in 30 kΩ NTC thermistor for automatic temperature compensation (ATC). Designed for compatibility with OHAUS ST-series benchtop and portable meters—including ST200, ST300, and ST500 models—the ST302 delivers stable mV output across the full aqueous pH scale (0.00–14.00), supporting accurate calibration and measurement under standard ambient and moderately elevated temperature conditions (0 °C to 80 °C). Its compact cylindrical form factor (120 mm × 12 mm) and lightweight plastic body (80 g) facilitate ergonomic handling and ease of immersion in beakers, flasks, and process vessels.
Key Features
- Combination design integrating pH-sensing glass membrane, double-junction Ag/AgCl reference system, and embedded 30 kΩ NTC temperature sensor for real-time ATC.
- Full-scale pH measurement range of 0.00–14.00 with optimized response time (<30 seconds to 95% stability in buffer solutions at 25 °C).
- Durable plastic body resistant to mechanical impact and common laboratory chemicals; suitable for both aqueous and mildly aggressive media.
- 1.1-meter shielded PVC cable with BNC connector ensures low-noise signal transmission and compatibility with industry-standard meter inputs.
- Designed for long-term stability: gel-filled electrolyte system minimizes liquid junction potential drift and reduces maintenance frequency.
- Compliant with ISO 3696 (Grade 3 water specifications for calibration) and aligned with ASTM E70 and EN ISO 17442 guidelines for pH electrode performance verification.
Sample Compatibility & Compliance
The ST302 is validated for use with aqueous samples including buffers, biological fluids, food extracts, wastewater, and pharmaceutical preparations. It is not recommended for non-aqueous solvents, highly viscous slurries, or strong oxidizing agents (e.g., >10% hypochlorite or concentrated HNO₃), which may degrade the glass membrane or clog the junction. The electrode meets CE marking requirements for electromagnetic compatibility (EN 61326-1) and safety (EN 61010-1). While not certified for intrinsically safe or hazardous area use, its construction supports GLP-compliant documentation when used within validated laboratory workflows. Calibration traceability follows NIST-traceable pH buffer standards (e.g., NIST SRM 186, 4699, 184), and data integrity is maintained through instrument-level audit trails when paired with compliant OHAUS ST-series meters supporting 21 CFR Part 11–enabled software.
Software & Data Management
The ST302 functions as a hardware transducer and does not incorporate onboard memory or digital communication protocols. All data acquisition, calibration logging, and report generation occur via the connected OHAUS ST-series meter. When used with ST500 or ST300 meters equipped with USB or RS232 interfaces, raw mV and temperature values are exportable to CSV or Excel formats. Firmware updates and calibration history management adhere to ALCOA+ principles (Attributable, Legible, Contemporaneous, Original, Accurate, Complete, Consistent, Enduring, Available) when configured in audit-trail mode—ensuring alignment with GMP and GLP regulatory expectations for analytical instrumentation.
Applications
- Routine pH monitoring in academic teaching labs and undergraduate chemistry curricula.
- QC testing of raw materials and finished products in food & beverage, cosmetics, and water treatment facilities.
- Environmental analysis of surface water, effluent, and soil leachates per EPA Method 150.1 and ISO 10523.
- Bioprocess support during fermentation and cell culture where temperature-compensated pH tracking is required.
- Calibration verification of multi-parameter probes and validation of pH meter performance across multiple buffer points (e.g., 4.01, 7.00, 10.01).
FAQ
Is the ST302 compatible with non-OHAUS meters?
Yes—its standard BNC connector and analog mV output allow integration with most benchtop pH meters featuring BNC input and manual or automatic temperature compensation capability.
What is the recommended storage solution?
Store upright in 3 M KCl solution or OHAUS Electrolyte Storage Solution (Cat. No. ST-ES); avoid distilled water or dry storage to prevent glass membrane dehydration.
How often should the electrode be calibrated?
Perform two-point calibration before each daily use or prior to critical measurements; verify slope (>95%) and offset (±30 mV) against fresh NIST-traceable buffers.
Can the ST302 be used for ORP measurements?
No—while structurally similar to ORP electrodes, the ST302 features a pH-specific glass membrane and is not optimized for redox potential detection.
Does it support sterilization or autoclaving?
No—the plastic body and gel electrolyte are not rated for steam sterilization; repeated exposure to >80 °C or pressurized steam will compromise junction integrity and sensor response.
