Compliance and light sources
ISO and the US EPA are the two main organisations that govern the design critera of a turbidimeter and set specifications or even regulations for turbidity measurement. Compliance to one of these standards is regionally based.
For example, the United States of America along with many other countries in Central and South America and parts of Asia follow the US EPA 180.1 regulations.
Europe, Africa as well as some Asian countries and parts of Australia follow ISO 7027 regulations. It should be noted that having regulatory compliant turbidity readings is only necessary when you are testing for regulatory reporting purposes.
In these cases, a local authority can advise the user of their reporting requirements.
Essentially every turbidimeter available has been designed to comply with the guidelines set by one of these organisations.
There are many process control applications for turbidity that are outside the scope of regulatory reporting.
Selection of the light source
ISO 7027 requires the use of an Infrared light source (860-nm LED); while US EPA 180.1 requires the use of a Tungsten or “white light” source. Upon evaluation and approval, the US EPA will also allow the use of other light sources, such as red LEDs and lasers, on a case-by-case basis.
Lovibond® offers a variety of different light sources for turbidity measurement that vary around the world.
|Selection guide for the different versions of light sources from Lovibond® Ability of the technology to meet the requirement (WL = White Light; IR = Infrared; RED = Red Light; L = Laser)|
|EPA compliance||-||-||WL, RED, L|
|Colour removal||WL||RED, L||IR|
|Lowest stray light||WL||RED, IR||L|
|Detection of dissolved solids||IR||RED, L||WL|
|Detection of sub-micron particles||IR||WL||RED, L|
|Filtration optimisation||WL||IR, RED||L|