HACH GLI 3400 Series High-Performance Conductivity Sensors

Overview

The HACH GLI 3400 Series High-Performance Conductivity Sensors are engineered for continuous, high-accuracy measurement of electrical conductivity and resistivity across a broad spectrum of industrial and environmental water applications—from ultrapure water in semiconductor rinse loops and pharmaceutical water-for-injection (WFI) systems to high-conductivity boiler feedwater, cooling tower blowdown, and wastewater effluent. These sensors operate on the principle of two-electrode or four-electrode conductometric measurement, with cell geometry optimized to minimize polarization effects and ensure stable output under variable flow, temperature, and fouling conditions. Designed for integration into HACH SC1000, CL17, or third-party PLC/DCS-based online monitoring platforms, the GLI 3400 delivers traceable, reproducible data compliant with ASTM D1125, ISO 7888, and USP standards for purified water and water-for-injection testing.

Key Features

• Factory-characterized electrode constant (K-value) — each sensor is individually measured and assigned a unique four-digit K-factor (0.05, 0.5, 1.0, 5.0, or 10.0 cm⁻¹), traceable to NIST-certified reference solutions
• DRY-CAL® calibration methodology — eliminates the need for wet calibration at installation; users input the factory-measured slope and temperature offset directly into the transmitter, enabling immediate operational readiness without process interruption
• Wide thermal operating envelope: –20 to 200 °C, with rapid thermal response time (<30 s to 90% step change) ensured by low-mass platinum or stainless-steel sensing elements and optimized thermal conduction paths
• Multiple mechanical mounting configurations: compression-fit, non-metallic universal, boiler/condensate-rated, and hygienic tri-clamp flange options — all rated for pressures up to 100 psig at 200 °C
• Chemically resistant construction materials including PEEK, Hastelloy C-22, 316L SS, and custom ceramic insulators — validated for long-term stability in aggressive oxidizing, chlorinated, or high-pH environments
• Integrated Pt1000 or Pt100 RTD for simultaneous, co-located temperature compensation — minimizing spatial error between conductivity and thermal measurement points

Sample Compatibility & Compliance

The GLI 3400 series supports real-time analysis of aqueous matrices ranging from deionized water (0.055 µS/cm) to concentrated brines (>200 mS/cm). Its electrode constant flexibility allows optimal resolution across dynamic ranges: K = 0.05 cm⁻¹ for ultrapure water (0.002–20 MΩ·cm), K = 1.0 cm⁻¹ for municipal drinking water (100–2000 µS/cm), and K = 10.0 cm⁻¹ for seawater or industrial process streams (up to 200,000 µS/cm). All variants comply with IEC 61508 SIL2 functional safety requirements when paired with compatible HACH transmitters. The sensor design meets FDA 21 CFR Part 11 data integrity expectations for audit-trail-capable systems and supports GLP/GMP documentation workflows via HACH’s DataStream™ software.

Software & Data Management

When connected to HACH SC1000 or GLI 5000-series transmitters, the GLI 3400 enables full digital diagnostics—including electrode degradation trending, coating detection alerts, and automatic temperature-compensation validation logs. Calibration history, K-factor metadata, and thermal drift coefficients are stored onboard and exportable via Modbus TCP or HART 7. Data export formats include CSV and XML, compatible with LIMS platforms (e.g., LabWare, Thermo Fisher SampleManager) and enterprise SCADA systems. Firmware updates are delivered via secure HTTPS, with cryptographic signature verification ensuring firmware authenticity per NIST SP 800-193 guidelines.

Applications

• Power generation: Condensate polishing, boiler water cycle control, and turbine gland steam monitoring
• Pharmaceutical manufacturing: Purified water (PW), water-for-injection (WFI), and clean steam condensate quality assurance per USP and EU Annex 1
• Semiconductor fabrication: UPW resistivity monitoring in sub-10 nm node tool rinse lines
• Food & beverage: CIP solution concentration tracking, syrup dilution control, and wastewater BOD/COD correlation
• Municipal utilities: Source water characterization, desalination plant feed/pre-treatment monitoring, and reclaimed water compliance reporting (EPA Method 120.1)

FAQ

How does DRY-CAL® eliminate the need for field calibration?
DRY-CAL® leverages factory-determined slope (µS/cm per mV) and temperature offset (°C) values—measured in certified reference solutions under controlled conditions. These parameters are digitally embedded and applied by the transmitter during initialization, removing reliance on operator-performed wet calibration.
Can the GLI 3400 be used in sanitary applications?
Yes—hygienic tri-clamp (ISO 2852) and DIN 11851 flanged versions are available with electropolished 316L SS bodies and FDA-compliant elastomer seals, validated for SIP (steam-in-place) cycles up to 135 °C.
What is the recommended maintenance interval for fouling-prone installations?
Under continuous operation in moderate-fouling environments (e.g., cooling towers), visual inspection and cleaning every 3–6 months is advised; in high-fouling applications (e.g., activated sludge), automated ultrasonic or chemical cleaning interfaces can be integrated via optional relay outputs.
Is the probe suitable for explosive atmospheres?
When installed with HACH’s intrinsically safe IS-rated transmitters (e.g., SC200-IS), the GLI 3400 complies with ATEX II 2G Ex ia IIC T4 Ga and IECEx Ex ia IIC T4 Ga certification for Zone 0/1 hazardous locations.