Process Photometers

Process Photometers

Process photometers are inline optical analyzers that use UV, visible (VIS), or near-infrared (NIR) absorbance - and, in relevant configurations, optical turbidity methods - to quantify concentration, color, purity, or particulate behavior in real time. The category is engineered for hygienic and high-integrity applications, with designs suited to demanding process conditions and regulated production environments where off-line sampling is slow or contamination-prone.

The key benefit is immediate, non-reagent measurement that replaces or reduces laboratory sampling while improving control authority. Inline absorbance and turbidity signals enable tighter endpoint detection, faster detection of process deviations, and improved yield protection during filtration, separation, and purification steps. Hygienic design suitability supports high-purity and sanitary production where sample handling is a significant risk factor.

Selection is wavelength- and application-driven. NIR absorbance may be used for biological growth or composition trends, dual-wavelength methods for color compensation, and UV absorbance for concentration or impurity monitoring depending on analyte spectra. Turbidity measurement via scattered light is applied for filter control, with forward-scatter approaches used to detect filter breaks rapidly at low turbidity. Devices are also positioned for hazardous-area use where approvals are required.

Implementation includes optical pathlength selection, flow cell geometry, and calibration strategy. Endress+Hauser highlights NIST-traceable certified calibration filters as a way to reduce calibration complexity, and low-volume flow cells to support fast response and improved yield. Process photometers can be combined with other liquid analysis parameters (pH, conductivity, oxygen) through a shared transmitter platform such as Liquiline CM44P, enabling coherent multi-parameter packages.

Typical applications include chromatography, fermentation monitoring, filtration control, phase separation and crystallization observation, condensate monitoring, and heat exchanger leak detection where optical changes indicate contamination or process intrusion. They are also used in purity and color monitoring across life sciences, pharmaceuticals, food & beverage, chemical, and related process industries.

Miller Mechanical Specialties, an exclusive authorized representative of sales and service for Endress+Hauser.