TURBIDITY METER TN50 - Turbidity Tester Automatic calibration with progress bar, on-screen guide and low battery indicator, and automatic power off, etc. Autoranging from 0 to 1000 nephelometric turbidity units (NTU). Meets ISO 7027 (DIN EN 27027) performance criteria. Infrared light source - delivers laboratory accuracy. US EPA recognized standards are included in sealed vials. Large coloured TFT easy-to-read screen (blue backlight). Easy to use. Easy to calibrate. Modern design. Designed for the rigors of rugged field applications. Waterproof. Convenient rugged carrying case.   Measuring Method  ISO 7027 compliant nephelometric Method（90°ï¼‰ Measuring Range 0 ~ 1000 NTU, automatic range selection: 0.01~19.99 NTU, 20.0~99.9 NTU, 100~1000 NTU. Resolution 0.01 / 0.1 / 1 NTU Indication Error ≤ ±2 % of reading±stray light Repeatability ≤ ± 1% of reading or 0.02 NTU, subject to whichever is greater Calibration Standards 0.02 NTU, 20.0 NTU , 100 NTU, 800 NTU(Polymer) Light Source Infrared-emitting diode（850nm wavelength） Detector Silicon photovoltaic Display TFT Color screen Sample Vials Φ25×60 mm, high borosilicate glass with screw cap Sample Volume 18 ml Operating Temp. Range 0~50℃ Power Supply 4x “AA” Alkaline Batteries IP Rating IP67