Using a 90 degree scatter measurement, the system provides high sensitivity measurement with unmatched zero stability. Turbidity measurements down to 0.001 NTU or as high as 4000 NTU can be measured with the same monitor, eliminating the need for separate high and low range instruments.
The turbidity sensor used in the A15/76 monitor is a planer sensor with the light source and photo detector mounted on a flat face. Lenses in front of the light source direct the beam of light at a 45-degree angle into the sample. Another lens in front of the photodetector collects the 90 degree scattered light and directs it to the detector. The signal generated by the detector is amplified inside the sensor for transmission to the display unit. Periodic pulsing of the light source allows the sensor zero to be adjusted automatically for improved stability in low-range applications.
Turbidity sensors are available for measurement in a pressurized flowcell or for direct submersion in open tanks. A 1-1/2” flow T assembly is also available for direct in-line measurements. The flowcell is required for very low measurements (0-4 NTU), while the submersion unit may be used for higher turbidity applications such as wastewater effluent or raw water.
Air bubbles are a common problem in many turbidimeters. ATI’s turbidity sensor is designed to operate under pressure to eliminate the sample degassing that often causes air bubble errors. Sample pressure is not dropped until the sample exits the measuring chamber, resulting in more reliable measurements. The turbidity electronics unit is a compact panel-mount instrument providing an LCD display of turbidity value, as well as indication of alarm status and instrument diagnostics. For stand-alone applications, a NEMA 4X wall-mount enclosure is available.