| HCHO |
 |
Performance
| Measuring Range |
|
| Number of Pump Strokes |
|
| Correction Factor |
|
| Sampling Time |
1.5 minutes per pump stroke |
| Detecting Limit |
0.05 ppm (n=5) |
| Colour Change |
Yellow → Reddish Brown |
| Reaction Principle |
3HCHO + (NH2OH)3H3PO4 → H3PO4
H3PO4 + Base → Phosphate
|
| Coefficient of Variation |
10% (for 0.1 to 0.5 ppm), 5% (for 0.5 to 5 ppm) |
| Shelf Life |
3 Years |
| 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 |
| Aldehydes |
|
+ |
Reddish brown |
| Ketones |
|
+ |
Reddish brown |
| Acid Gases |
|
+ |
Red |
| Organic acids |
|
No |
No |
Other substance measurable with this detector tube
| Substance |
Correction Factor |
No. of pump strokes |
Measuring Range |
| Diisobutyl ketone |
5.8 |
4 |
0.58 to 29 ppm |
| Methaldehyde |
0.65 |
3 |
0.065 to 3.25 ppm |
| Propionaldehyde |
7.6 |
1 |
0.76 to 38 ppm |
| 91L Tube Reading (n=1) |
0.2 |
0.5 |
1 |
2 |
3 |
4 |
5 |
| Benzaldehyde (ppm) |
2 |
4 |
9 |
22 |
40 |
63 |
92 |
| 91L Tube Reading (n=1/2) |
0.2 |
0.5 |
1 |
2 |
3 |
4 |
5 |
| Cyclohexanone (ppm) |
10 |
30 |
60 |
130 |
220 |
330 |
470 |
| Calibration gas generation |
Diffusion tube method |
| TLV-TWA |
TLV-STEL |
Explosive range |
| - |
C 0.3 ppm |
7.0 to 73% |
