The measurement principle is based on the strong absorption of UV light by the chromophore N-O according to the Beer-Lambert law: - Measurement time: < 10 seconds - Interference with chlorides: no - Reagents or consumable: no - Periodic change of electrode or lamp or parts: no - Maintenance: very low - Filtering: no need - Automatic cleaning system: yes - Operating cost: low - Size: compact - Weight: 14 kg approx. - Transportable by car or passenger plane: yes - Installation time: few minutes