| |
|
|
|
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. |
|
Calibration gas generation |
Diffusion tube method |
|
TLV-TWA |
TLV-STEL |
Explosive range |
|
0.5 ppm |
2.5 ppm |
1.3 to 7.1% |
|
|
|
|
|
|
Gastec Tubes and
Sampling Pump
