MeasuringRange 10 to 20 ppm 20 to 500 ppm 500 to 1500ppm Number of Pump Strokes 2 1 1/2 Correction Factor 1/2 1 3 SamplingTime 30 seconds per pumpstroke DetectingLimit 1 ppm (n=2) ColorChange White → Yellow ReactionPrinciple C6H5CH:CH2+H2S2O7 → CondensationPolymer Coefficient ofVariation 15% (for20 to 100 ppm), 10% (for 100 to 500 ppm) ShelfLife 3Years Correctionsfor temperature & humidity Unnecessary Store the tubes at cool and darkplace.