Water & Environment
Platinum-Cobalt (Pt-Co) / Hazen / APHA color
- Platinum-Cobalt (Pt-Co) / Hazen / APHA color scale according to ASTM D 1209,BS 5339:76 (1993), DIN 53409 and ISO 6271-1:2004(E)
- Direct real time measurement of water color
- High resolution measurement
- Automatic cleaning
- No maintenance
Description of the scale
The Platinum-Cobalt (Pt-Co) color scale measures the “yellowness” of a liquid and is well suited for quality control and contamination detection. Also known as Hazen, or APHA scale, is a standardized method used to measure the intensity of yellow color in liquids. It assigns a color value from 0 (completely clear) to 500 (deep yellow).
Introduced in 1892 by chemist Allen Hazen and adopted and standardized by the American Public Health Association (APHA), the scale is recognized and utilized globally across various industries to ensure quality control of products and water supplies. All three terms (Pt-Co, Hazen, or APHA) describe the same measurement system and are incorporated into national and international standards.
Why are accurate measurements of water color important?
Water from aquifers often contains varying amounts of iron, which imparts a reddish-brown color, easily detectable with a color analyzer. This iron contamination can stain sinks, baths, clothes, and appliances. High levels of ferric iron in drinking water pose risks such as gastrointestinal issues, teeth discoloration, and long-term health problems, especially for infants and vulnerable groups.
Ferric iron in drinking water is a significant concern, making precise color measurements crucial to prevent environmental damage and health risks. To remove iron at the treatment plant, soluble ferrous iron must first be oxidized into solid ferric iron, typically through aeration or the use of oxidizing agents like potassium permanganate. The ferric iron is then removed using sand filters. Inaccurate color measurements can result in excessive chemical use, product waste, and failure to comply with regulations.
The Pt‑Co scale is used to evaluate pollution levels in wastewater and for drinking water quality control and regulation. But it can also be used to measure and control the concentration of iron in groundwater.
The Platinum-Cobalt color scale assigns a color value from 0 (completely clear) to 500 (deep yellow)
Iron rich mineral water spring
Platinum-Cobalt (Pt-Co) / Hazen / APHA color application note
Platinum Cobalt color analyzer
The Kemtrak Platinum Cobalt color analyzer is a maintenance free industrial photometric analyzer that can accurately monitor water color from highly polluted waters (>1000 Pt/Co units) down to clear liquids at <1 Pt/Co units. Real time measurement results are displayed in units of PCU (Pt/Co), Hazen or APHA.
The Kemtrak DCP007 LED process photometr uses a high performance long life LED light source with robust industrial fiber optics to provide a measurement with very highprecision. A proprietary dual wavelength four channel measurement technology allows accurate measurement of both highly colored and trace color levels. The primary “absorbing” UV-VIS wavelength accurately measures water color, while the second reference NIR wavelength, which is not influenced by the water color, compensates for turbidity and/or fouling of the optical windows.
Since optic fibers are used to transfer light to the measurement point and back, the measurement cell contains no electronics, moving parts or sources of heat.
Standard measurement cells are manufactured in robust sanitary grade stainless steel and use sapphire windows to provide a long and maintenance free operation.
Calibration is simplified using an automated QuickCal one point calibration. Measurement drift from LED light or filter aging is negligible and instrument recalibration is not required.