Apera Instruments, AI483, TN500 Portable White Light Turbidity Meter with GLP Data Logger, EPA 180.1 CompliantApera TN420 is built with a tungsten filament lamp as the light source and uses the 90° scattering method, which is compliant with the U.S EPA 180.1 method for the determination of turbidity in drinking, ground, surface, and saline waters, domestic and industrial wastes. The instrument is designed for water quality professionals, offering long-term reliability in high-accuracy turbidity measurement with an intuitive operating system and simple calibration.Features:Intelligent functions such as automatic calibration, operation navigation, parameter setup, real-time clock display, calibration date check, automatic power off, low voltage indication, and a replaceable tungsten filament lamp.Large TFT color screen with blue background for measurement mode, green background for calibration mode.Operation guidance and reminders in the process of calibration, measurement and parameter setting.TruReadTM measurement mode automatically takes multiple consecutive readings, and calculate their average, minimum and maximum value, as well as displaying each set of data in a brief test report. TruReadTM is a much better way to determine the true turbidity of your samples, rather than relying on just one reading. It's especially suitable for sample solutions with rapid settling and continuous measurement changes.Zero turbidity error reminder: the instrument has zero-point calibration and zero-point error reminder to ensure measurement accuracy for low turbidity solutions.200 sets of data storage with USB data output to PC (Windows-based).3.7V rechargeable lithium battery can supply power for over 20 hours of continuous measurement. The battery life is 5 times longer compared with tungsten lamp turbidimeter in the market using AA alkaline batteries.Multi-language operating system, including English, Spanish & Simplified Chinese.The instrument's structure meets IP67 water-resistant grade and is suitable for use in harsh environments.