Turbidity Sensors and Transmitters

Turbidity Sensors and Transmitters

Turbidity measurement quantifies light scattering caused by suspended particles, providing a fast indicator of water clarity and solids content at low to moderate concentrations. Sensors typically use nephelometric or backscatter optical arrangements, and transmitters convert the optical signal into standardized turbidity units with filtering, diagnostics, and outputs for control and reporting. Designs often include features to manage fouling, such as wipers, air blast cleaning, or anti-fouling coatings.

The benefit is immediate detection of solids excursions that affect process performance, filtration loading, and compliance. Turbidity is commonly used as a surrogate for particulate breakthrough and treatment efficacy, enabling rapid response to upsets such as filter failure, coagulant underdose, or hydraulic disturbances. Continuous turbidity trends also support optimization of backwash intervals, coagulant dosing, and settling performance, reducing operating cost while maintaining product water quality.

Typical applications include drinking water treatment (filter effluent and combined filter effluent monitoring), surface water intake monitoring, and wastewater final effluent trending. Turbidity is also used in industrial water systems to protect membranes, control clarification, and verify rinse quality in hygienic applications. In environmental monitoring, turbidity supports runoff studies, construction compliance, and receiving water impact assessments.

Installation and method selection are important for trustworthy readings. Sensor location should represent the process stream and avoid bubbles, excessive vibration, or stagnant zones that can trap solids. For low turbidity measurements, controlling stray light and maintaining optical cleanliness are critical. For higher turbidity or solids-heavy streams, backscatter methods and robust cleaning strategies improve stability and reduce maintenance burden.

Operationally, turbidity instruments provide the best outcomes when cleaning, verification, and alarm strategies are engineered into routine practice. Diagnostics that detect fouling, lamp degradation, or abnormal signal behavior help maintain data integrity. Integration with flow and filter control enables automated responses such as divert-to-waste, alarm escalation, or filter run termination. With properly maintained turbidity measurement, clarity control becomes faster, more stable, and more defensible.

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