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The Kemtrak DCP007 photometer measures at two wavelengths. A primary "absorbing" wavelength is used to measure the substance being monitored while a "non absorbing" reference wavelength is used to compensate for turbidity, air bubbles and/or fouling.

Applying the Beer-Lambert law (below), the concentration of the sample can be calculated.

Fiber optics are used to shine a precisely focused light beam through the process medium and back to a silicon photo-detector. A second photo-detector is used directly on the lamps to compensate for temperature effects and aging. The resulting measurements are very accurate with low drift and long-term calibration stability.


The attenuation of the transmitted light beam caused by light absorbing substances in the process medium is mathematically described by the Beer-Lambert law.

A = ε l c where:


A = absorbance (= - log transmittance)


ε = molar absorptivity coefficient


L = optical path length


C = concentration of absorbing species



The Kemtrak DCP007 photometer is ideally suited for industrial environments where simplicity, stability and zero maintenance is vital.

Measurement principle