| CnHm |
 |
Performance
| Measuring Range |
| 0.015 to 0.03“ |
0.03 to 0.6% |
0.6 to 1.2% |
|
| Number of Pump Strokes |
|
| Correction Factor |
|
| Sampling Time |
1 minute per pump stroke |
| Detecting Limit |
0.003% (n = 2) |
| Colour Change |
Orange → Dark green |
| Reaction Principle |
CnHm + Cr6++ H2SO4 → Cr3+ |
| Coefficient of Variation |
10% (for 0.03 to 0.1 %), 5% (for 0.1 to 0.6 %) |
| Shelf Life |
3 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 |
| Acetylene |
3% |
+ |
Dark brown (whole layer) |
| Propane |
0.2% |
+ |
Dark brown (whole layer) |
| Aromatic HCs |
500 ppm |
+ |
Dark green |
| Alcohols, Esters, Ethers |
|
+ |
Dark green |
| Halogenated HCs. |
5000 ppm |
+ |
Dark green |
| Hydrogen sulphide |
500 ppm |
+ |
Dark green |
| sulphur dioxide |
500 ppm |
+ |
Green |
Other substance measurable with this detector tube
| Substance |
Correction Factor |
No. of pump strokes |
Measuring Range |
| Heptane |
Factor: 1.0 |
1/2, 1 or 2 |
0.015 to 1.2% |
| Isooctane |
Factor: 0.9 |
1 |
0.027 to 0.54% |
| Octane |
Factor: 1.2 |
1 |
0.036 to 0.72% |
| Calibration gas generation |
Static gas dilution method |
| TLV-TWA |
TLV-STEL |
Explosive range |
| 300 ppm |
500 ppm |
1.4 to 7.6% |
