Process Photometers

Process Photometers

Process photometers are inline optical instruments used to measure absorption in UV and in NIR/VIS bands, turning light attenuation into actionable concentration or quality information. This category is positioned for inline measurement of UV absorption and NIR/VIS absorption across industries, providing a continuous, reagent-free alternative to periodic sampling for many optical indicators. Where a strong optical correlation exists, photometry provides rapid response suitable for control loops and early-warning alarms.

Photometric measurement generally uses a defined optical path, a light source, and detectors tuned to wavelength bands relevant to the target application. UV absorbance can correlate to dissolved organics and related surrogate parameters, while VIS/NIR absorbance can correlate to color, concentration, or composition changes in many process fluids. Offerings commonly include sensors and assemblies, and may integrate with transmitter platforms (Liquiline family noted for this category) depending on the configuration and parameter needs.

The principal benefits are speed, continuity, and minimal consumable burden. Inline photometry can support fast process corrections, reduce dependence on reagents and sample transport, and provide high-resolution trending for process optimization. Continuous absorbance monitoring also improves detection of short-duration events such as contamination slugs, breakthrough in treatment steps, or rapid changes during cleaning and changeover sequences. Because photometric signals can be trended at high frequency, they often reveal process dynamics that lab data cannot capture.

Applications span water and wastewater, chemical processing, food and beverage, life sciences, mining, and pulp and paper. In water treatment, UV absorbance monitoring is frequently used as an indicator related to organic content changes and treatment performance shifts. In industrial processes, VIS/NIR absorbance can be applied to concentration or color monitoring, supporting consistent product quality and improved detection of off-spec conditions. Utility applications benefit from continuous optical monitoring where fast response reduces operational risk.

Selection depends on optical suitability and maintainability. Key factors include wavelength band relevance, optical path length for expected concentrations, window fouling potential, and cleaning strategy (manual or automated). Installation configuration (inline flow cell vs. immersion) should match hydraulics, solids content, and required response time. Commissioning typically includes correlation to lab references and establishing alarm thresholds appropriate to process variability and compliance expectations.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.