HACH UVAS eco sc UV Absorption Online Analyzer

Overview

The HACH UVAS eco sc UV Absorption Online Analyzer is an industrial-grade, reagent-free instrument engineered for continuous, real-time monitoring of dissolved organic matter (DOM) in water streams using ultraviolet absorbance at 254 nm. It operates on the fundamental photometric principle that aromatic compounds—particularly those containing conjugated double bonds or polycyclic aromatic hydrocarbons—exhibit characteristic absorbance in the far-UV region. By quantifying this absorbance and normalizing it to path length and sample absorbance at a reference wavelength (550 nm), the analyzer reports Specific UV Absorbance at 254 nm (SAC254), a well-established surrogate parameter correlated with chemical oxygen demand (COD), total organic carbon (TOC), and disinfection byproduct (DBP) precursor concentration. Its dual-beam optical architecture—featuring simultaneous sample and reference detection—actively compensates for signal drift induced by fouling, lamp aging, power fluctuations, and particulate interference, ensuring long-term measurement stability without recalibration. The probe is designed for direct submersion or flow-through installation and integrates seamlessly with HACH’s sc100 universal controller for configuration, diagnostics, and data handling.

Key Features

• Reagent-free, maintenance-optimized operation—eliminates consumables, hazardous chemicals, and associated disposal protocols
• Dual-beam UV photometry at 254 nm with 550 nm turbidity compensation, delivering high reproducibility in variable water matrices
• Integrated stainless-steel (316L) wiper blade system enabling autonomous cleaning under high-fouling conditions—no external air supply or compressed gas required
• Compact, robust probe design (Ø75 × 323 mm, 3.3 kg) rated for continuous immersion in raw wastewater, surface water, and treated effluent
• Two isolated 4–20 mA analog outputs configurable for SAC254, temperature, or diagnostic status—compatible with DCS, SCADA, and PLC systems
• sc100 controller support enables audit-trail-capable data logging, user-access control, and compliance-ready reporting aligned with FDA 21 CFR Part 11 and ISO/IEC 17025 documentation practices

Sample Compatibility & Compliance

The UVAS eco sc is validated for use across diverse aqueous environments: drinking water sources, municipal wastewater influent/effluent, industrial process streams, and stormwater runoff. It maintains accuracy within pH 4.5–9.0 and temperatures from 2 °C to 40 °C. Its 1 mm optical path length minimizes scattering artifacts while preserving sensitivity across the full 5–1500 m⁻¹ SAC254 range. Turbidity compensation at 550 nm adheres to principles consistent with ISO 7027 for suspended solids correction. When deployed with sc100 firmware v3.2+, the system supports electronic signature-enabled calibration logs, event-driven data export, and timestamped maintenance records—facilitating GLP and GMP-aligned operational qualification (OQ) and performance qualification (PQ) protocols.

Software & Data Management

Data acquisition, visualization, and alarm management are handled via the HACH sc100 controller’s embedded web interface or HACH Insight software platform. All measurements—including SAC254, temperature, lamp intensity, wiper cycle count, and self-diagnostic flags—are time-stamped and stored locally with configurable retention (up to 1 year). Export formats include CSV and XML for integration into LIMS or enterprise analytics tools. Firmware updates preserve historical calibration coefficients and user-defined thresholds. Remote access via secure HTTPS enables off-site troubleshooting while maintaining network segmentation compliance. Audit trails record all configuration changes, output scaling modifications, and manual cleaning events—supporting regulatory readiness for EPA NPDES permit reporting and EU Water Framework Directive (WFD) monitoring obligations.

Applications

• Real-time organic load tracking at wastewater treatment plant influent channels to optimize biological process control (e.g., SRT adjustment, DO setpoint modulation)
• Effluent compliance monitoring for COD surrogates where traditional wet-chemistry methods are impractical due to space, labor, or safety constraints
• Early-warning detection of organic contamination events in drinking water distribution networks or reservoir intakes
• Process feedback control in membrane filtration plants—correlating SAC254 trends with fouling rate and backwash scheduling
• Research applications requiring high-frequency DOM profiling in limnological or biogeochemical studies

FAQ

Does the UVAS eco sc require daily calibration or standard solutions?
No. It is factory-calibrated and relies on stable LED optics and dual-beam referencing. Field verification with NIST-traceable quartz standards is recommended annually or after major maintenance.
Can the probe operate under submerged pressure beyond 0.5 bar?
No. It must be installed at atmospheric pressure or with pressure relief upstream. For pressurized pipe applications, use a side-stream bypass with flow regulation.
Is SAC254 directly equivalent to COD or TOC?
SAC254 is a strong empirical correlate—not a direct replacement—for COD or TOC. Site-specific correlation models (e.g., SAC254 vs. lab-measured COD) are required for quantitative estimation.
What maintenance tasks are required monthly?
Visual inspection of the quartz window, verification of wiper blade integrity, and cleaning of the probe body with mild detergent—typically completed in under 60 minutes without disassembly.
How does the system handle high-turbidity or algae-laden samples?
The 550 nm compensation channel corrects for non-absorptive scattering. For extreme cases (>100 NTU), optional mechanical pre-filtration or periodic manual window wipe may be advised.