HACH 3400 Digital Contact Conductivity Sensor
| Brand | HACH |
|---|---|
| Origin | Imported |
| Manufacturer Type | Manufacturer |
| Model | 3400 |
| Detection Parameter | Single-parameter (Conductivity) |
| Portability | Pen-style |
| Application Environment | Industrial process, laboratory, and field monitoring |
| Conductivity Range | 0–200,000 µS/cm |
| TDS Range | 0–400,000 ppm |
| Resistivity Range | 0.001–20 MΩ·cm |
| Temperature Range | −20 to +200 °C |
| Accuracy | ±0.01% of reading |
| Minimum Resolution | 0.1 µS/cm |
Overview
The HACH 3400 Digital Contact Conductivity Sensor is a high-precision, intelligent electrochemical transducer engineered for reliable, real-time measurement of aqueous solution conductivity in demanding industrial, municipal, and laboratory environments. Based on the principle of two-electrode AC conductometric measurement—employing a constant-frequency sinusoidal excitation signal to minimize polarization effects and electrode fouling—the 3400 delivers stable, drift-resistant performance across wide dynamic ranges. Its fully digital architecture eliminates analog signal degradation, enabling direct communication with HACH’s sc200 or sc1000 universal digital controllers via a standardized RS-485 interface. The sensor operates without manual calibration setup or wiring configuration; automatic device recognition upon insertion ensures true plug-and-play functionality, significantly reducing commissioning time and operator error.
Key Features
- Digital-native design with embedded microprocessor and non-volatile memory for sensor-specific calibration coefficients and diagnostics
- Robust titanium body construction (for standard 3422sc variants) or 316 stainless steel (for 3455sc sanitary models), ensuring long-term chemical resistance in aggressive media
- Integrated temperature compensation using a built-in Pt1000 RTD, supporting automatic linear or non-linear (e.g., ASTM D1125) compensation algorithms
- Multiple cell constants (0.05, 0.5, 1.0, 5.0, and 10 cm⁻¹) available via interchangeable sensor bodies—each matched to specific application requirements (ultra-pure water, boiler feedwater, wastewater, or high-salinity brines)
- Pre-terminated 7-meter (standard) or 6-meter + 1-meter extendable cable assemblies with IP68-rated digital mating connectors
- Compliance with IEC 61508 SIL 2 functional safety requirements for use in safety-related loops when integrated with certified controllers
Sample Compatibility & Compliance
The 3400 series supports continuous monitoring of conductive aqueous solutions including potable water, cooling tower fluids, reverse osmosis permeate, boiler blowdown, condensate return streams, and chemical dosing lines. It is not intended for non-aqueous, highly viscous, or suspended-solid-laden samples exceeding 5% v/v without mechanical protection or flow conditioning. All variants meet CE marking requirements and conform to EN 61326-1 (EMC) and EN 61010-1 (safety). For regulated pharmaceutical or food-grade applications, the 3455sc sanitary variant complies with 3-A Sanitary Standards #63-03 and EHEDG Doc. 8, and is suitable for Clean-in-Place (CIP) and Steam-in-Place (SIP) cycles up to 140 °C. Calibration traceability aligns with ISO/IEC 17025-accredited reference standards.
Software & Data Management
When paired with the sc200 or sc1000 controller, the 3400 enables full audit-trail capability compliant with FDA 21 CFR Part 11 requirements—including electronic signatures, user-level access control, and immutable event logging of calibration, verification, and maintenance actions. HACH’s SC1000 Configuration Software (v4.0+) supports remote firmware updates, sensor health diagnostics (e.g., electrode impedance trending, cable continuity checks), and export of timestamped data in CSV or Modbus TCP format. Historical conductivity, TDS, resistivity, and temperature values are stored onboard for up to 30 days at 1-minute intervals, facilitating root-cause analysis during process excursions.
Applications
- Power generation: Monitoring condensate purity and boiler feedwater resistivity to prevent turbine corrosion
- Pharmaceutical manufacturing: USP compliant conductivity verification in purified water (PW) and water for injection (WFI) distribution systems
- Food & beverage: In-line control of CIP rinse conductivity to validate cleaning efficacy
- Municipal water treatment: Real-time salinity intrusion detection in coastal intake systems
- Chemical processing: Concentration control of acid/base solutions and electrolyte baths
- Laboratory QC: Benchtop verification of standard solutions per ASTM D1125 and ISO 7888
FAQ
Can the 3400 sensor be used with legacy analog controllers?
No—it is exclusively compatible with HACH’s digital sc200 and sc1000 platforms. Analog equivalents (e.g., 3422, 3444, 3455) must be selected for use with older SC100 or HQ series controllers.
What is the maximum allowable pressure rating for the 3400 sensor?
Standard titanium-bodied 3422sc sensors are rated to 10 bar (145 psi) at 25 °C; sanitary 3455sc variants with 316SS housing support up to 16 bar (232 psi) under ASME BPE-compliant mounting.
Is temperature compensation configurable?
Yes—users may select between linear (NaCl-based), non-linear (ASTM D1125), or custom polynomial compensation curves directly via the controller interface.
Does the sensor require periodic recalibration?
While factory-calibrated and stable over time, HACH recommends quarterly verification against NIST-traceable KCl standards per ISO/IEC 17025 guidelines—especially in GMP or GLP-regulated environments.
How is sensor health monitored?
The embedded diagnostic engine continuously reports electrode impedance, cable integrity, and thermal drift; deviations beyond predefined thresholds trigger maintenance alerts in the controller’s event log.
