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% |
