Application Range
Substance: Hydrochloric acid: nitric acid:
Standard Measuring Range: 1 to 10 ppm / 1 to 15 ppm
Number of Strokes n: 10 / 20
Time for Measurement: approx. 1.5 min / approx. 3 min
Standard Deviation: ± 30%
Color Change: blue -› yellow
Ambient Operating Conditions
Temperature: 5 to 40 °C for HCl
For HNO3 measurements, the tube scales are applicable only to
20 °C. Where the temperature is different, the measuring result
must be multiplied as follows: Temperature °C Factor
40 0.3
30 0.4
10 2
Absolute Humidity: max 15 mg H2O / L
Reaction Principle
HCl and/or HNO3 + pH indicator -> yellow reaction product
Cross Sensitivity
50 ppm nitrogen dioxide result in almost the same reading as 2 ppm nitric acid. 10 ppm hydrogen sulfide or 5 ppm nitrogen dioxide do not effect the reading. Chlorine concentrations in excess of 1 ppm change the entire indicating layer to a yellow-green.