Benzene |
NO.121SP |
| C6H6 |  |
 |
Performance
| Measuring Range | 0.2 to 20 ppm | 20 to 66 ppm |
| Number of Pump Strokes | 3 | 1 |
| Correction Factor | 1 | 3.3 |
| Sampling Time | 1.5 minutes per pump stroke | |
| Detecting Limit | 0.1 ppm (n=3) | |
| Colour Change | White → Brown | |
| Reaction Principle | 2C6H6+ HCHO → C6H5CH2C6H5 + H2O C6H5CH2C6H5 + H2S2O7 → Condensation poiymer |
|
| Coefficient of Variation | 10% (for 0.2 to 5ppm) , 5% (for 5 to 20 ppm) | |
| Shelf Life | 2 Years | |
| Corrections for temperature & humidity | Unnecessary | |
| Store the tubes at cool and dark place. | ||
Possible coexisting substances and their interferences (NOTE)
| Substance | Concentration | Interference | Change colour by itself to |
| Hexane | 500 ppm | No | No |
| Toluene | 300 ppm | No | No |
| Xylene | 350 ppm | No | No |
Aromatic hydrocarbons other than benzene are trapped in the brown layer in the pretreatment tube. If the pretreatment reagent is entirely consumed (whole brown layer turns to dark brown), a higher reading will be given. |
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| Calibration gas generation | Diffusion tube method |
| TLV-TWA | TLV-STEL | Explosive range |
| 0.5 ppm | 2.5 ppm | 1.3 to 7.1% |
