Huake Instrument HK-328 Online pH/ORP Analyzer

Overview

The Huake Instrument HK-328 Online pH/ORP Analyzer is an industrial-grade process analytical instrument engineered for continuous, high-stability measurement of hydrogen ion activity (pH) and oxidation-reduction potential (ORP) in aqueous streams. It operates on the principle of potentiometric measurement using a glass membrane electrode system coupled with a reference junction—compliant with fundamental electrochemical standards defined in ISO 7027 and ASTM D1293. Designed specifically for low-conductivity applications, the HK-328 delivers reliable performance in ultrapure water environments such as power plant demineralized water, condensate, and generator stator cooling water—where conventional pH sensors often suffer from unstable junction potentials and slow response.

Key Features

• Robust cast-aluminum housing with ESD-resistant finish, rated IP65 for harsh industrial enclosures and wet-location mounting.
• Embedded microcontroller architecture with surface-mount technology (SMT) PCBs, ensuring long-term thermal stability and resistance to electromagnetic interference (EMI) per IEC 61326-1.
• Dual-parameter real-time display (pH + temperature or ORP + temperature) on a backlit 192 × 64 graphic LCD with language toggle (English/Chinese).
• Automatic temperature compensation (ATC) using Pt1000 or thermistor inputs; user-selectable ATC range (0.1–60.0 °C) accommodates both ambient and elevated-temperature process lines.
• Extended signal transmission capability: analog output remains stable over distances up to 500 meters when paired with shielded twisted-pair cabling and proper grounding.
• Triple-combination pH electrode with integrated reference and temperature sensor—optimized for low-ionic-strength media and featuring rapid T₉₀ response (<90 s at 25 °C) and drift <0.02 pH/day under controlled calibration intervals.
• Dual isolated 4–20 mA outputs, each independently assignable to pH, ORP, or temperature; configurable alarm relays support fail-safe shutdown logic per IEC 61511.

Sample Compatibility & Compliance

The HK-328 is validated for use with clean, low-turbidity aqueous samples meeting strict particulate and chemical constraints: suspended solids ≤5 µm, zero colloidal content, and absence of oils or surfactants that could foul the glass membrane or clog the liquid junction. Minimum sample conductivity should exceed 1 µS/cm to ensure stable reference potential—consistent with USP guidance for pharmaceutical water systems. The analyzer complies with CE marking requirements (EMC Directive 2014/30/EU, Low Voltage Directive 2014/35/EU), and its electrical isolation meets IEC 61010-1 safety standards for measurement category CAT II. While not certified for SIL-rated loops, its hardware architecture supports integration into Safety Instrumented Systems (SIS) when deployed with external logic solvers.

Software & Data Management

Local data handling includes non-volatile memory storing ≥100,000 timestamped measurement records (pH, ORP, temp, alarms) with cyclic overwrite protection. Historical trend visualization is accessible via front-panel navigation—supporting zoom, scroll, and export-ready time-range selection. Communication protocols include Modbus RTU over RS-485 (default), optional Profibus DP v1 slave interface for Siemens PCS7 and TIA Portal integration, and HART 7.0 for field device configuration via handheld communicators or AMS Device Manager. All digital interfaces maintain full audit trail functionality—including parameter change logs with user ID and timestamp—enabling alignment with FDA 21 CFR Part 11 requirements when deployed with validated host SCADA or DCS platforms.

Applications

• Power generation: Continuous monitoring of boiler feedwater, condensate polishing loops, and hydrogen-cooled generator cooling circuits.
• Microelectronics: Ultrapure water (UPW) distribution systems where pH deviations >0.1 unit indicate resin exhaustion or carbon filter breakthrough.
• Pharmaceutical manufacturing: Purified Water (PW) and Water for Injection (WFI) loop surveillance per EU GMP Annex 1 and WHO TRS 970.
• Chemical process plants: Neutralization control in effluent treatment, caustic soda dosing feedback, and catalyst bath pH maintenance.
• Food & beverage: CIP rinse water verification and brine solution consistency tracking prior to pasteurization.

FAQ

Does the HK-328 support automatic calibration?

No—the HK-328 does not feature built-in auto-calibration; it requires manual two-point (e.g., pH 4.01/7.00 or 7.00/10.01) or three-point calibration using NIST-traceable buffer solutions. Calibration frequency depends on application severity but is typically recommended every 24–72 hours in critical UPW service.
Can the instrument operate in pressurized sample lines?

Yes—when used with the supplied flow-through cell assembly (rated to 10 bar), the HK-328 supports inline installation in pressurized loops. Proper pressure relief and flow regulation (6 L/h nominal) must be maintained upstream to prevent membrane stress or electrolyte leakage.
Is the electrode compatible with steam sterilization?

No—the triple-combination pH electrode is not autoclavable. For SIP (Steam-in-Place) applications, users must install a sanitary tri-clamp bypass cell with a removable electrode cartridge and follow ASME BPE 2022 cleaning validation protocols.
What diagnostic functions are available?

The unit provides real-time electrode diagnostics including asymmetry potential, slope (% of theoretical 59.16 mV/pH at 25 °C), and reference impedance—accessible via serial command or HART variable readout. Abnormal values trigger configurable warning indicators on the display and relay outputs.
How is firmware updated?

Firmware upgrades require connection to a PC via RS-485 and execution of Huake’s proprietary configuration utility (Windows only). Updates preserve all user settings and historical logs unless explicitly reset during procedure.