HACH GLI 3/4-inch Composite pH/ORP Electrode
| Brand | HACH |
|---|---|
| Origin | Imported |
| Manufacturer Type | Manufacturer |
| Model | GLI 3/4 |
| Pricing | Upon Request |
Overview
The HACH GLI 3/4-inch Composite pH/ORP Electrode is an industrial-grade, multi-configuration sensing element engineered for continuous, reliable measurement of hydrogen ion activity (pH) and oxidation-reduction potential (ORP) in demanding process environments. Based on potentiometric measurement principles—utilizing a glass pH-sensing membrane paired with a robust reference system featuring a dual-salt-bridge junction—the electrode delivers stable, reproducible electrochemical signals across fluctuating process conditions. Its modular mechanical design supports three primary installation modes—flow-through, immersion, and sanitary—enabling seamless integration into municipal wastewater treatment plants, chemical manufacturing lines, pulp & paper processing, and industrial effluent monitoring systems where sensor longevity, chemical resistance, and minimal process interruption are critical operational requirements.
Key Features
- Triple-installation flexibility: Compatible with standard 3/4″ NPT threaded fittings (flow-through), direct pipe-end immersion, or sanitary tri-clamp (2″) configurations.
- Dual-salt-bridge reference system: Minimizes electrolyte contamination and junction clogging, extending service life in high-suspended-solids or sulfide-rich streams.
- Chemically inert wetted materials: Ryton® (PPS) body for general-purpose models; PVDF (Kynar®) for insertion-type variants; 316 stainless steel-lined PVDF for sanitary applications.
- Integrated temperature compensation: Equipped with a built-in Pt1000 or thermistor element (model-dependent), enabling automatic temperature correction per NIST-traceable algorithms.
- Grounded reference design: Includes an internal grounding point to reduce electrical noise and improve signal stability in electrically noisy plant environments.
- Electrode versatility: Available with flat-surface, spherical, or HF-resistant glass membranes—each optimized for specific fouling tendencies, cleaning protocols, or hydrofluoric acid exposure.
Sample Compatibility & Compliance
The GLI 3/4 electrode demonstrates broad compatibility with aqueous matrices across pH 0–14 and ORP ranges from –1000 mV to +1000 mV. It maintains accuracy under pressures up to 10 bar (145 psi) and temperatures from 0 °C to 80 °C (short-term up to 90 °C). Wetted material selection adheres to FDA 21 CFR §177.2470 (PVDF), ASTM D471 (elastomer compatibility), and ISO 10993-5 (cytotoxicity screening). The sanitary variant complies with 3-A Sanitary Standards #74-01 and meets EHEDG Doc. 8 requirements for hygienic design. All configurations support GLP/GMP data integrity when paired with HACH SC1000 or HQ40d controllers equipped with audit-trail-enabled firmware.
Software & Data Management
When interfaced with HACH’s IntelliCAL™ or SC Series transmitters, the GLI 3/4 electrode supports digital diagnostics including junction resistance monitoring, glass impedance trending, and calibration history logging. Transmitter firmware enables configurable alarm thresholds for drift detection, out-of-range pH/ORP, and temperature deviation—exportable via Modbus RTU/TCP or HART 7. Data records comply with FDA 21 CFR Part 11 requirements when deployed with validated SC200/SC1000 platforms, including electronic signatures, user access controls, and immutable audit trails.
Applications
- Municipal wastewater influent/effluent monitoring and biological nutrient removal (BNR) control
- Industrial pretreatment systems handling heavy metals, cyanide, or chlorinated compounds
- Chemical dosing feedback loops for lime, caustic, or sulfuric acid addition
- Recirculating cooling water and boiler feedwater pH/ORP surveillance
- Food & beverage CIP rinse validation and Clean-in-Place endpoint detection
- Pharmaceutical water-for-injection (WFI) and purified water (PW) system verification
FAQ
What installation types does the GLI 3/4 electrode support?
It supports flow-through (via 3/4″ NPT tee), immersion (pipe-end mounting), and sanitary (2″ tri-clamp) configurations—with dedicated mechanical assemblies for each.
Is temperature compensation automatic?
Yes—integrated Pt1000 or thermistor elements enable real-time, transmitter-driven temperature compensation per IUPAC-recommended equations.
Can this electrode be used in hydrofluoric acid (HF) solutions?
Only when specified with the optional HF-resistant glass membrane; standard glass membranes are not HF-compatible.
How often should calibration be performed in continuous operation?
Calibration frequency depends on process stability; typical intervals range from daily (high-fouling wastewater) to weekly (clean process water), guided by drift thresholds set in the transmitter.
Does the dual-salt-bridge design require refilling or maintenance?
No—the dual-junction reference is sealed and gel-filled; it eliminates liquid electrolyte replenishment while resisting poisoning from Ag⁺, S²⁻, or CN⁻ ions.
