Turbidimeters offer a wide measurement range to suit various applications. Portable or benchtop turbidity meters commonly have ranges from 0-1000 NTU and support automatic range segmentation (e.g., 0.01-19.99 NTU; 20.0-99.9 NTU; 100-1000 NTU). Inline turbidity meters offer even wider ranges, with high-range models reaching 0-9999 NTU and low-range models focusing on finer measurement ranges such as 0–40 NTU.
Resolution refers to the smallest change in turbidity that the instrument can display, down to 0.001 NTU for low-turbidity measurements. Accuracy is typically expressed as a percentage error of the reading or a percentage error of full scale (FS), such as ±2% ±1 decimal place (within the 0-500 NTU range), or within ±5% FS. Repeatability can reach ±1% of the reading.
The type of light source determines the measurement standards the instrument conforms to. Infrared light sources (wavelength typically 850-880nm) comply with ISO 7027 international standards; white light sources (such as tungsten lamps or white LEDs) comply with US EPA 180.1 standards. Some high-end models employ a dual-light source (white light and infrared light) design to meet broader regulatory requirements.
The instrument's operating temperature range is typically 0℃ to 50℃. Sample temperature adaptability is generally 0℃ to 50℃, with some online sensor designs adapting to wider temperature ranges, such as -20℃ to 70℃. Furthermore, portable instruments often have high protection ratings (such as IP67) to withstand humid outdoor environments.
Modern turbidimeters are typically equipped with multiple data interfaces, including RS-485 (supporting Modbus and other protocols) for system integration, 4-20mA analog output for controller connection, and relay alarm output. For data management, USB interface data export is supported, and some models have built-in data storage functions, automatically storing hundreds to thousands of timestamped measurement values.
Calibration is crucial for ensuring measurement accuracy. Turbidimeters support single-point calibration (typically within a low measurement range, such as 0–40 NTU) or multi-point calibration (e.g., 1-point, 2-point, 4-point, or up to 6-point calibration). The standard substance used for calibration is primarily formalin standard solution; some instruments also provide their own standard series for calibration.
Power supply varies depending on the instrument type. Portable turbidimeters typically use DC batteries (e.g., four AAA alkaline batteries) and can support over 1200 measurements. Benchtop and online turbidimeters typically use AC power (e.g., 220V) or a DC regulated power adapter.
