Knick SE707 Online Dissolved Oxygen Analyzer

Overview

The Knick SE707 is a high-precision, hygienic online dissolved oxygen (DO) analyzer engineered for continuous, real-time monitoring in demanding industrial process environments. It operates on the principle of electrochemical amperometric detection using a Clark-type membrane-covered sensor element. Oxygen diffuses through a selective fluoropolymer membrane into an electrolyte-filled chamber, where it undergoes reduction at a cathode, generating a current linearly proportional to the partial pressure of dissolved O₂. This signal is digitally conditioned and temperature-compensated in real time using an integrated Pt1000 RTD, enabling accurate DO quantification across wide thermal and hydrostatic gradients. Designed specifically for critical applications in pharmaceutical water systems, bioreactor control, food & beverage production (e.g., beer fermentation, dairy pasteurization), and boiler feedwater management, the SE707 meets stringent requirements for measurement integrity, mechanical robustness, and regulatory traceability.

Key Features

• Electrochemical amperometric sensing with 1 ppb detection limit and 0.00–50.00 mg/L linear measurement range, validated per ISO 5814:2012 and ASTM D888–20
• Hygienic probe construction from electropolished 1.4435 (SS316L) stainless steel, fully compliant with EHEDG Doc. 8 (2022) for drainability and surface finish (Ra ≤ 0.8 µm)
• Steam-in-place (SIP) capable up to 135 °C, supporting GMP-compliant sterilization cycles without sensor removal or recalibration
• Integrated Pt1000 temperature sensor enabling automatic compensation across –5 to +121 °C, eliminating external temperature transmitter dependency
• Robust 2-wire 4–20 mA analog output with HART® 7 protocol support for configuration, diagnostics, and firmware updates via standard field communicators
• Two standard immersion lengths (120 mm and 220 mm) optimized for tank, pipe, and inline installation; optional sanitary tri-clamp (DIN 11851) and NPT thread fittings available
• Long-term stability of ±1% of reading per year, verified under accelerated aging tests per IEC 61298-2, minimizing calibration frequency in validated processes

Sample Compatibility & Compliance

The SE707 is validated for use in ultrapure water (UPW), purified water (PW), water-for-injection (WFI), wort, milk, cider, and low-conductivity boiler feed streams. Its fluoropolymer membrane exhibits negligible interference from chloride, sulfide, or CO₂, ensuring specificity in complex matrices. The device conforms to electromagnetic compatibility standards IEC 61326-1 (industrial environment) and functional safety requirements per IEC 61508 SIL 2 (hardware fault tolerance). For regulated life science applications, the analyzer supports audit-trail-enabled configuration logging and can be integrated into systems compliant with FDA 21 CFR Part 11 when deployed with Knick’s certified communication gateway and validated software tools.

Software & Data Management

Configuration, diagnostics, and calibration are performed via HART-enabled handheld terminals (e.g., Field Communicator 475) or PC-based Knick Device Manager software. All parameter changes—including zero/span values, temperature offset, damping time, and unit selection—are timestamped and stored in non-volatile memory with user-accessible revision history. Optional integration with SCADA, DCS, or MES platforms is supported through Modbus RTU (via optional interface module) or analog input mapping. Raw sensor data (mV output, temperature, status flags) is accessible for trending and statistical process control (SPC) analysis, aligning with ISO 9001 and Annex 1 (EU GMP) requirements for data integrity.

Applications

• Pharmaceutical Water Systems: Continuous DO monitoring in WFI storage & distribution loops to prevent biofilm nucleation and ensure USP & EP compliance
• Biotechnology Fermentation: Real-time control of dissolved oxygen setpoints in mammalian and microbial bioreactors to optimize cell growth and product yield
• F&B Production: In-line verification of deaeration efficiency during beer lagering, dairy UHT pre-heating, and juice aseptic filling
• Power Generation: Boiler feedwater oxygen scavenging control to mitigate corrosion in high-pressure steam cycles (ASTM D1066, VGB-R 410)
• Environmental Process Monitoring: Effluent aeration basin control in municipal wastewater treatment plants operating under DIN EN 1899-1

FAQ

Is the SE707 suitable for autoclave sterilization?
Yes — the sensor body and membrane assembly are rated for repeated SIP cycles at 135 °C for up to 30 minutes, meeting EHEDG and ASME BPE requirements.
Does it require daily calibration?
No — due to its long-term stability (±1% / year) and built-in temperature compensation, scheduled calibration intervals are typically 1–3 months depending on application severity and quality system requirements.
Can it be installed in pressurized pipelines?
Yes — the probe is rated for continuous operation at pressures from 0.2 to 6 bar, with optional high-pressure housings available for >6 bar service.
How is membrane replacement performed?
The fluoropolymer membrane is replaced as a factory-assembled cartridge; no electrolyte refilling or electrode polishing is required, reducing maintenance downtime to under 5 minutes.
Is third-party validation support available?
Knick provides IQ/OQ documentation templates, calibration certificates traceable to NIST standards, and on-site qualification support for GMP-regulated installations.