WTW VisoTurb 700IQ Portable Turbidimeter with Integrated Ultrasonic Cleaning

Overview

The WTW VisoTurb 700IQ is a high-precision, portable turbidimeter engineered for continuous or spot measurement of turbidity in liquid media using the nephelometric principle—specifically, 90° scattered light detection at 860 nm wavelength. Designed and manufactured in Germany, it complies strictly with EN ISO 7027 (identical to ISO 7027 and DIN EN 7027), ensuring metrological traceability and inter-laboratory comparability. Unlike conventional turbidimeters relying on visual or photometric endpoint interpretation, the VisoTurb 700IQ employs a fixed-angle, dual-detector optical architecture with temperature-stabilized LED excitation and calibrated reference channels, minimizing drift and enabling long-term stability without field recalibration. Its core application domain spans drinking water quality control, surface water monitoring, wastewater treatment effluent verification, and process water surveillance in pharmaceutical and food & beverage production—where regulatory adherence to turbidity limits (e.g., WHO guidelines ≤ 1 NTU, US EPA 181.1, or EU Directive 98/83/EC) is mandatory.

Key Features

• Integrated ultrasonic cleaning system (SonicClean™) operating at resonant frequency to prevent biofilm, sediment, or mineral deposit accumulation on the sapphire optical window—reducing maintenance intervals by up to 80% compared to manual cleaning protocols.
• SensCheck™ real-time self-diagnostic functionality continuously monitors optical path integrity, cleaning transducer performance, and signal-to-noise ratio; triggers configurable alarm outputs upon deviation thresholds (e.g., >5% signal attenuation or cleaning cycle failure).
• Auto-ranging measurement across seven decades (0.05–4000 FNU) with dynamic resolution scaling: 0.001 FNU below 0.4 FNU, 0.01 FNU up to 4 FNU, 0.1 FNU up to 40 FNU, and 1 FNU above 400 FNU—ensuring optimal precision across low-turbidity potable water and high-solids industrial effluents.
• Optical assembly sealed behind single-crystal sapphire window (Mohs hardness 9), resistant to abrasion, chemical corrosion, and thermal shock—validated for operation in chlorinated, saline, and mildly acidic environments (pH 4–10).
• Robust mechanical construction: V4A stainless steel (1.4571) housing rated IP68 and pressure-resistant up to 10 bar, supporting submersible deployment at depths up to 15 m with minimum immersion of only 7 cm.
• Factory-calibrated against certified Formazin and SiO₂ standards per DIN 38402-51; calibration data embedded in device memory with full audit trail—supporting GLP/GMP compliance without user intervention.

Sample Compatibility & Compliance

The VisoTurb 700IQ is validated for use with clear to highly turbid aqueous matrices, including chlorinated tap water, river/lake water, activated sludge supernatants (SS 100 mg/L DOC), where Mie scattering effects may introduce bias beyond ±2%. Regulatory alignment includes full conformance with EN ISO 7027 for method equivalence, DIN 38402-51 for accuracy validation, and ISO 5725-2 for repeatability assessment (<0.015% RSD or ≥0.006 FNU). For FDA-regulated facilities, the device supports 21 CFR Part 11-compliant data logging when paired with WTW’s IQ SensorNet software (audit trail, electronic signatures, and secure user roles).

Software & Data Management

When connected via IQ cable to WTW’s IQ SensorNet platform (v4.2+), the VisoTurb 700IQ enables time-synchronized data export in CSV, PDF, or XML formats—with timestamped metadata (temperature, sensor status, cleaning cycles, diagnostic flags). The software enforces ALCOA+ principles: attributable, legible, contemporaneous, original, accurate, complete, consistent, enduring, and available. All calibration events, firmware updates, and alarm logs are cryptographically signed and stored with immutable timestamps. Remote configuration (e.g., cleaning interval, alarm thresholds, unit switching between FNU/NTU/TEF/mg/L SiO₂/g/L TS) is supported over Modbus RTU or Ethernet/IP protocols—facilitating integration into SCADA or LIMS environments.

Applications

• Drinking water utilities: Real-time verification of filtration efficiency at rapid sand filter outlets and final distribution points—ensuring turbidity remains below 0.1 FNU per AWWA Standard G300.
• Municipal wastewater plants: Monitoring clarifier overflow turbidity and disinfection contact chamber influent to validate UV or chlorine dose efficacy (turbidity < 2 FNU required for effective UV transmission).
• Pharmaceutical manufacturing: Post-purification water-for-injection (WFI) and purified water (PW) testing per USP and EP 2.2.2, where particulate load must remain below 0.05 NTU.
• Environmental monitoring networks: Battery-powered deployment in remote stream gauging stations with cellular telemetry—leveraging low power draw (1.5 W) and internal temperature compensation (0–60 °C).
• Industrial process control: Inline turbidity feedback for coagulant dosing optimization in paper mill whitewater circuits or metal finishing rinse tanks.

FAQ

Does the VisoTurb 700IQ require periodic recalibration in the field?

No. It is factory-calibrated against NIST-traceable Formazin and SiO₂ standards and retains calibration stability for ≥12 months under normal operating conditions. Only verification checks using certified standard suspensions (e.g., StabCal®) are recommended quarterly per ISO/IEC 17025.
Can the ultrasonic cleaning function operate continuously?

It operates on programmable duty cycles (default: 5 min ON / 55 min OFF) to balance fouling prevention with transducer longevity. Continuous activation is disabled above 40 °C to prevent thermal stress on piezoelectric elements.
Is the sensor compatible with non-aqueous solvents?

No. It is designed exclusively for aqueous systems. Exposure to organic solvents (e.g., ethanol, acetone) or strong oxidizers (e.g., concentrated H₂O₂) will degrade O-rings and compromise IP68 integrity.
How is measurement uncertainty quantified across the full range?

Per DIN 38402-51, expanded uncertainty (k=2) is ±0.006 FNU below 1 FNU, ±0.5% of reading from 1–2000 FNU, and ±1% above 2000 FNU—validated via interlaboratory comparison studies.
What communication protocols does the IQ interface support?

RS-485 Modbus RTU (default), optional Ethernet/IP or Profibus DP via external gateway modules—enabling direct integration into DCS or PLC-based control architectures.