| CnHm |
 |
Performance
| Measuring Range |
| 30 to 1000 ppm |
1000 to 2000 ppm |
|
| Number of Pump Strokes |
|
| Correction Factor |
|
| Sampling Time |
2 minutes per pump stroke |
| Detecting Limit |
5 ppm (n=2) |
| Colour Change |
Brownish yellow → Dark green |
| Reaction Principle |
CnHm + Cr6++ H2SO4 → Cr3+ |
| Coefficient of Variation |
10% (for 30 to 300 ppm), 5% (for 300 to 1000 ppm) |
| 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 |
| Hydrogen sulphide |
|
+ |
Dark brown |
| Acetylene |
|
+ |
Dark brown |
| Aromatic HCs |
|
+ |
Dark green |
| Esters, Ethers,Alcohols |
|
+ |
Dark green |
| sulphur dioxide |
|
+ |
Dark green |
Organic solvents ( C3) |
|
+ |
Dark green |
Other substance measurable with this detector tube
| Substance |
Correction Factor |
No. of pump strokes |
Measuring Range |
| Allyl chloride |
Factor: 34 |
1/2 |
0.1 to 3.4% |
| Heptane |
Factor: 1.0 |
1 or 2 |
30 to 2000 ppm |
| Isobutene |
Factor: 22 |
1 |
0.07 to 2.2% |
| Calibration gas generation |
Static gas dilution method |
| TLV-TWA |
TLV-STEL |
Explosive range |
| 300 ppm |
500 ppm |
1.4 to 7.6% |
