HACH Digital Differential pH/ORP Sensor
| Brand | HACH |
|---|---|
| Origin | Imported |
| Manufacturer Type | Manufacturer |
| Instrument Type | Pen-style |
| Parameter Types | Dual (pH & ORP) |
| Measurement Range | pH 0–14, ORP −1500 to +1500 mV |
| Resolution | 0.01 pH |
| Calibration Buffers | pH 4.01, 7.00, 10.01 |
| Sensor Interface | Digital (HACH SC Series Protocol) |
| Cable Length | 4.5 m integrated |
| Digital Adapter Included | Part #6120600 (for legacy analog sensor retrofit) |
| Temperature Compensation | Integrated Pt1000 RTD |
| Housing Materials | Ryton®, PVDF, or 316SS/PVDF (model-dependent) |
| Compliance | Designed for ASTM D1293, ISO 10523, USP <791>, and EPA 150.1–compliant monitoring workflows |
Overview
The HACH Digital Differential pH/ORP Sensor is a precision electrochemical transducer engineered for continuous, high-stability measurement of hydrogen ion activity (pH) and oxidation-reduction potential (ORP) in aqueous process streams, wastewater effluents, drinking water distribution systems, and industrial cooling loops. Unlike conventional analog electrodes, this sensor employs a digital differential architecture—utilizing a reference electrode with active liquid junction compensation and a high-impedance glass sensing element—to minimize drift, junction potential errors, and noise susceptibility. Its embedded microprocessor performs real-time temperature compensation via an integrated Pt1000 RTD, eliminating external thermistor dependency and ensuring traceable accuracy across variable thermal conditions. The sensor communicates via HACH’s proprietary digital SC-series protocol over a shielded, twisted-pair cable, delivering noise-immune signal transmission immune to ground-loop interference—a critical advantage in electrically noisy plant environments.
Key Features
- Digital “plug-and-play” interface compatible with HACH SC200 and SC1000 universal digital controllers—no manual configuration, DIP-switching, or analog scaling required.
- Differential measurement design reduces common-mode interference and improves long-term stability in low-conductivity or high-ionic-strength samples.
- Integrated Pt1000 temperature sensor enables automatic, NIST-traceable temperature compensation per ASTM D1293 and ISO 10523 requirements.
- Multiple housing options: flexible Ryton® body for general-purpose use; PVDF-insertion variant for aggressive chemical exposure; hygienic 316 stainless steel/PVDF for sanitary applications (e.g., pharmaceutical utilities).
- Factory-calibrated with documented as-shipped verification against NIST-traceable buffer standards (pH 4.01, 7.00, 10.01); supports two- or three-point field calibration using standard buffers.
- Built-in diagnostics—including electrode impedance monitoring, reference junction status, and signal integrity flagging—support predictive maintenance and GLP-compliant audit trails.
Sample Compatibility & Compliance
The sensor is validated for use in potable water, wastewater, seawater, brine solutions, and mild-to-moderate caustic or acidic process streams (pH 0–14). Specific models (e.g., PC1R3A) incorporate HF-resistant glass for hydrofluoric acid-containing matrices. All variants meet IP68 submersion rating (4.5 m, 72 h) and comply with RoHS and REACH directives. When deployed with SC200/SC1000 controllers configured for 21 CFR Part 11 compliance (audit trail, electronic signatures, user access control), the system satisfies data integrity requirements for regulated water quality monitoring under EPA Method 150.1 and EU Directive 98/83/EC.
Software & Data Management
Data output is natively supported in HACH’s LogRite™ and Intellesis™ software platforms, enabling time-synchronized logging, trend visualization, alarm thresholding, and automated report generation (PDF/CSV). Controller firmware includes configurable data hold, min/max tracking, and rate-of-change alerts. All calibration events, sensor diagnostics, and measurement logs are timestamped and stored with immutable metadata—enabling full traceability for internal QA audits or regulatory inspections under GLP/GMP frameworks.
Applications
- Real-time pH/ORP monitoring in chlorine disinfection contact tanks (CT calculations per EPA guidance).
- Control of neutralization reactors in chemical manufacturing and metal finishing operations.
- Monitoring of anaerobic digesters and denitrification basins via ORP setpoint feedback loops.
- Sanitary process water validation in biopharmaceutical clean steam and WFI systems (USP ).
- Corrosion potential assessment in closed-loop cooling towers and boiler feedwater circuits.
FAQ
Does this sensor require special cabling or termination?
No—each unit ships with a factory-terminated, 4.5-meter shielded digital cable and a molded connector compatible with SC200/SC1000 controller ports. Analog retrofit is possible using HACH part #6120600 digital adapter.
Can it be used in high-salinity or low-conductivity water?
Yes—the differential design ensures stable readings down to 20 µS/cm conductivity; for ultra-pure water (<1 µS/cm), optional flow-cell mounting and pressurized reference chamber configurations are recommended.
Is temperature compensation automatic and adjustable?
Yes—Pt1000-based compensation is fully automatic and non-adjustable by design to preserve metrological integrity; offset correction is only permitted during calibration routines per ISO/IEC 17025 guidelines.
What documentation is provided for regulatory submissions?
Each sensor includes a Certificate of Conformance listing materials, calibration data, and traceability to NIST SRMs; optional IQ/OQ protocols and 21 CFR Part 11 validation packages are available upon request.
