Turbidity Sensors and Transmitters

Turbidity Sensors and Transmitters

Turbidity sensors and transmitters measure the optical “cloudiness” of liquids caused by suspended particles and extend into related measurements such as total solids and suspended solids. Turbidity measurement is used for quality assurance and process control across drinking water production, effluent monitoring, sludge concentration measurement in wastewater treatment, seawater inlet monitoring for desalination, and product loss detection in dairies and other production environments.

Instrument selection is strongly dependent on turbidity regime and process variability. Nephelometric sensors are used for low-turbidity media such as potable water and measure according to ISO 7027 / EN 27027 using a 90° detector geometry. Suspended solids sensors are applied for high turbidity (for example in wastewater), while absorption sensors are positioned for extreme fluctuations and for cases where unambiguous readings are needed to reliably detect product losses.

The measurement principles vary accordingly. Total/suspended solids sensors use backscattered light with detectors positioned at defined angles (e.g., 90° and 135°) to interpret scatter intensity and compute solids in units such as g/L or %TS. Nephelometric sensors measure scattered light at 90° to quantify turbidity, while absorption turbidity meters measure attenuation of light along a direct path and may use multiple path lengths to improve reliability across varying particle concentrations.

Benefits include a complete instrument set - turbidity meters, total solids meters, suspended solids meters - supported by matching transmitters, accessories, and mounting options. Installation flexibility spans inline pipe mounting, flow assemblies for fast measurement without product loss, and open-basin/channel/tank installations using holders. Transmitters can display multiple common units (including FNU, FTU, NTU), supporting standardization across sites and reporting frameworks.

Verification and calibration can be simplified through solid-state references that avoid liquid standards such as Formazin, reducing handling burden while supporting consistent validation. A broad selection of assemblies (fixed, immersion, flow-through, retractable) supports fit-for-purpose deployment, allowing turbidity measurement to be engineered around hydraulic conditions, fouling exposure, and service access rather than compromised by installation constraints.

At Eastern Controls, We are proud to be the exclusive authorized sales and service representative for Endress+Hauser.