A method for measuring the color of potable water in terms of an easily reproducible color standard is essential to water engineers responsible for the distribution of supplies for public consumption.
Color determinations are useful for detecting any irregular contamination of the supply due to natural disasters (floodwaters, earthquakes, etc.), checking the efficiency of the filter beds, of the decolorizing treatments and maintaining a standard clarity. Turbid or colored waters are unappetizing, and even slight variations in the color of the supply result in complaints from consumers.
The American Public Health Association in “Standard Methods for the Examination of Water and Wastewater”, 1989, specifies that the color of water shall be expressed by comparison with a series of solutions containing known amounts of platinic chloride and cobalt chloride. These solutions are known as “Hazen Color Standards”, and are adopted in British Standard 2690: 1970 Part 9, British Standard 6068: 1968 Section 2.22 and International Standard ISO 2211: 1973. They are also used for non-aqueous applications in ASTM D1209-52 and D1045-58.
These Hazen Color Standards have been matched with Lovibond® glass to produce permanent color standards, and discs containing nine color standards exactly matching the Hazen standards are available for use with the Lovibond® Comparator 2000+.
Designed for measuring unsaturated samples that are below the sensitivity of a normal, hand-held comparator system, the Comparator 2000+ Nesslerizer employs longer path lengths that make it possible to accurately match samples that produce very pale colors visually.
The built-in magnifying prism allows the user to easily view the glass color disc standard and the sample to be matched side-by-side. Glass plungers eliminate distracting meniscus curvatures.
Correct lighting conditions are essential for accurate color comparison. The lighting units provide a constant and stable light using a tungsten halogen lamp and a calibrated color temperature correction filter. This guarantees correct lighting conditions 24 hours a day and under all ambient light conditions.