Process Photometers

Process Photometers

Process photometers measure specific dissolved substances by analyzing light absorption through a sample, often using colorimetric methods with or without reagents. Many systems include an optical cell, light source, detector, and signal processing, and may incorporate reagent dosing and controlled reaction timing to form a measurable color complex. Transmitters or integrated controllers provide calculated concentration outputs, diagnostics, and interfaces for automation systems.

The value lies in selective, continuous measurement of parameters that are difficult to infer indirectly. Photometric analysis can target species such as chlorine compounds, ozone, phosphate, silica, iron, manganese, and other color-forming analytes depending on method selection. Continuous results support faster process correction than laboratory-only approaches, reduce chemical waste, and improve compliance confidence through trend visibility and event capture.

Common applications include drinking water treatment (disinfectant and nutrient-related measurements), wastewater treatment (phosphate and other regulated constituents), and industrial utilities (silica monitoring for boiler protection, iron monitoring for corrosion control). In process industries, photometric analyzers support product quality by tracking key additives or contaminants in aqueous streams. They also serve as verification instruments for critical control points where excursions have high cost.

Implementation considerations include sample conditioning, optical cleanliness, and reagent handling where applicable. Filters, degassing, and controlled temperature can improve stability and reduce measurement noise. Optical paths should be engineered to minimize bubbles and fouling; automated cleaning or wiper systems may be appropriate in dirty services. Reagent storage, shelf life, and waste disposal must be planned to support safe and consistent operation.

Operational performance improves with automated verification routines and strong diagnostics. Zero and span checks, drift tracking, and maintenance counters help maintain data integrity. Integration with control systems enables closed-loop dosing, alarm escalation, and reporting. When photometric measurement is paired with upstream turbidity and flow signals, it becomes easier to distinguish true concentration changes from sampling or hydraulic artifacts.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.