What is the difference between Hach turbidmimeters whose product name has ISO and those that don't?
What Turbidimeter is appropriate for EPA and ISO conformance?
Turbimeter models which contain the ISO designation use a LED light source and use the Turbidity unit FNU to report the Turbidity value. These turbidimeters are primarily used outside the U.S. to meet ISO regulated testing methods. Turbidimeters with the EPA designation use a EPA required Tungsten bulb for its light source and report Turbidity concentrations in NTU's.