WTW TetraCon 325 Standard Conductivity Electrode for Aqueous Solutions
| Brand | WTW |
|---|---|
| Origin | Germany |
| Model | TetraCon 325 |
| Detection Parameter | Conductivity (Single-Parameter) |
| Portability | Portable |
| Intended Use | Laboratory |
| Conductivity Range | 1 µS/cm to 2 S/cm |
| Electrode Constant | 0.475 cm⁻¹ ±1.5% |
| Cable Length | 1.5 m (replaceable) |
| Stem Diameter | 15.3 mm |
| Total Length | 162.5 mm |
| Immersion Depth (max) | 120 mm (T < 100 °C) |
| Pressure Rating | –2 bar |
| Connector | 8-pin plug, IP67 |
| Sensing Element IP Rating | IP68 |
| Temperature Sensor | Integrated NTC thermistor (30 kΩ at 25 °C), graphite housing |
| Temp. Range | –5 to +100 °C |
| Temp. Accuracy | ±0.2 K |
| T₉₉ Response Time | <20 s |
Overview
The WTW TetraCon 325 is a robust, four-electrode conductivity sensor engineered for precise and stable measurement of electrical conductivity in aqueous solutions under laboratory conditions. Based on the principle of alternating current (AC) four-electrode conductometry, this electrode eliminates polarization effects and minimizes errors from electrode fouling or surface contamination—critical advantages over traditional two-electrode designs. Its graphite sensing elements and epoxy resin body provide chemical resistance to common laboratory reagents, while the integrated NTC temperature sensor ensures automatic temperature compensation per DIN EN 27888 and ISO 7888 standards. Designed specifically for compatibility with WTW’s MultiLine P4 portable meters, the TetraCon 325 delivers reliable performance across a wide dynamic range—from ultrapure water monitoring (1 µS/cm) to high-conductivity industrial process streams (up to 2 S/cm). Its compact, ergonomic form factor and IP68-rated sensing tip support routine immersion in beakers, flasks, and flow-through cells without risk of ingress-related drift.
Key Features
- Four-electrode AC conductometric design for high reproducibility and reduced polarization error
- Stable electrode constant of 0.475 cm⁻¹ ±1.5%, calibrated and traceable to national standards
- Integrated NTC thermistor (30 kΩ at 25 °C) housed in graphite for rapid thermal equilibration (T₉₉ < 20 s) and ±0.2 K accuracy
- Epoxy resin stem (black, 15.3 mm Ø) with graphite sensing elements—resistant to corrosion, abrasion, and mild organic solvents
- Replaceable 1.5 m shielded cable with rugged 8-pin IP67 connector for long-term signal integrity
- Optimized immersion depth (min. 36 mm, max. 120 mm at ≤100 °C) and pressure rating of –2 bar for safe use in pressurized or vacuum-assisted systems
- No internal electrolyte or gel—eliminates drying-out, leakage, or refilling requirements typical of reference electrodes
Sample Compatibility & Compliance
The TetraCon 325 is validated for use with deionized water, tap water, wastewater, buffer solutions, saline media, and low-viscosity aqueous process streams. It is not intended for strong oxidizing acids (e.g., concentrated HNO₃), molten salts, non-aqueous solvents (e.g., acetone, ethanol >10%), or highly viscous suspensions. When used with WTW MultiLine P4 instruments, measurements comply with ASTM D1125–22 (Standard Test Methods for Electrical Conductivity of Water) and ISO 7888:2019 (Water quality — Determination of electrical conductivity). The electrode’s construction meets RoHS Directive 2011/65/EU and WEEE recycling requirements; disposal must follow local electronic waste regulations.
Software & Data Management
While the TetraCon 325 is an analog sensor requiring connection to a compatible meter (e.g., MultiLine P4), its seamless integration enables full audit-trail functionality when paired with WTW’s LabX® software via USB or Bluetooth. All conductivity and temperature readings are timestamped, associated with user ID and calibration history, and exportable in CSV or PDF formats compliant with GLP and FDA 21 CFR Part 11 requirements. Firmware updates and calibration verification logs are stored directly on the meter, supporting laboratory accreditation under ISO/IEC 17025.
Applications
- Quality control of purified water in pharmaceutical manufacturing (PW, WFI pre-checks)
- Monitoring conductivity in boiler feedwater, cooling tower cycles, and desalination pretreatment
- Environmental analysis of surface water, groundwater, and effluent discharge compliance
- Academic research involving ionic strength profiling in electrochemical cell studies
- Calibration verification of benchtop conductivity meters using standard KCl solutions (e.g., 0.01 mol/kg)
- Routine QC testing in food & beverage labs for rinse water, brine, and syrup dilutions
FAQ
Can the TetraCon 325 be used in hot water above 100 °C?
No. Maximum immersion depth is limited to 120 mm at temperatures below 100 °C. For higher-temperature applications, consult WTW’s InLab®系列 high-temp electrodes.
Is the electrode constant adjustable or user-calibratable?
The electrode constant is factory-determined and fixed at 0.475 cm⁻¹ ±1.5%. Users perform system calibration using certified KCl standards; no manual constant adjustment is required or supported.
How often should the electrode be cleaned?
Cleaning frequency depends on sample matrix. For clean water samples, rinsing with deionized water between measurements suffices. After exposure to oils, carbonates, or precipitates, follow the recommended cleaning protocol using warm detergent solution or 10% acetic acid.
Does the TetraCon 325 require storage solution?
No. Unlike pH or ion-selective electrodes, it contains no liquid junction or reference electrolyte. Store dry in ambient air—no hydration or soaking is necessary.
Can the cable be replaced in the field?
Yes. The 1.5 m cable features a standardized 8-pin mating connector and is designed for user replacement without tools or soldering. Replacement cables (e.g., WTW order no. 200100) maintain full IP67 integrity and signal fidelity.
