Formaldehyde

NO.91M
HCHO
Performance
Measuring Range
8 to 20 ppm 20 to 2000 ppm 2000 to 6400 ppm
Number of Pump Strokes
2 1 1/2
Correction Factor
0.4 1 3.2
Sampling Time 1.5 minutes per pump stroke
Detecting Limit 4 ppm (n=2)
Colour Change Yellow → Red
Reaction Principle 3HCHO + (NH2OH)3H3PO4 → H3PO4
H3PO4 + Base → Phosphate
Coefficient of Variation 10% (for 8 to 200 ppm), 5% (for 500 to 2000 ppm)
Shelf Life 2 Years
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
Acrolein 5 times + Red ( 20 ppm)
Acetaldehyde 1/6 time + Red ( 3 ppm)
Calibration gas generation Diffusion tube method
TLV-TWA TLV-STEL Explosive range
- C 0.3 ppm 7.0 to 73%


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