Models 800 and 800-P meet EPA specifications for measurement of turbidity in drinking water. Their drift-free, accurate readings make these instruments suitable for testing municipal water and any aqueous solutions in which control of clarity is critical. Models 800 and 800-P are true nephelometers, measuring the amount of light scattered at a right angle from a beam of light passing through the test sample. Test results are read directly in NTUs on a LCD digital readout. The turbidimeters are pre-calibrated and a simple zero adjustment is the only step required prior to testing.