Formaldehyde

NO.91LL
HCHO
Performance
Measuring Range 0.05 to 1.0 ppm
Number of Pump Strokes 5
Correction Factor 1
Sampling Time 1.5 minutes per pump stroke
Detecting Limit 0.03 ppm (n=5)
Colour Change Yellowish Brown → Reddish Brown
Reaction Principle 3HCHO + (NH2OH)3H3PO4 → H3PO4
H3PO4 + Base → Phosphate
Coefficient of Variation 10% (for 0.05 to 0.3 ppm), 5% (for 0.5 to 1.0 ppm)
Shelf Life 1 Year
Corrections for temperature & humidity Temperature correction is necessary
Store the tubes in the refrigerator to keep at 10ºC (50ºF) or below.
Possible coexisting substances and their interferences (NOTE)
Substance Concentration Interference Change colour by itself to
Ammonia   Yellow
(Unclear demarcation)
Nitrogen dioxide   No Pale pink
Aldehydes 1/3 time +
(Unclear demarcation)
Reddish brown
Ketones 1:1 +
(Unclear demarcation)
Reddish brown
Toluene 10 ppm No No
Calibration gas generation Diffusion tube method
TLV-TWA TLV-STEL Explosive range
- C 0.3 ppm 7.0 to 73%


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