| 被动扩散式检测管是用来测定较长时间下气体浓度的时量平均值（TWA），采用自然扩散的方式。 这种检测管里面填充有吸附剂及反应剂，气体以一定的速率被均匀吸附，从而出现较为明显均匀的变色。 检测工作场所人员的有害气体暴露量时，用右图的检测管夹（710）放置在人员衣领处即可。 检测有害气体在工作场所的分布时，把该检测管固定放置一段时间后就可检测出来。也可用来进行长时间的检测。 | |
特点 简洁，轻巧，方便多用 直接读数 不需取样设备 图例 A-切断处 B-吸附剂 C-检测剂 | 检测管夹 No. 710 |
Performance
| Measuring Range | 2 to 600 ppm |
| Sampling Hours | 1 to 10 hours |
| Detecting Limit | 2 ppm (10 hours) |
| Colour Change | Yellow → Reddish Brown |
| Reaction Principle | 3CH3COC2H5+ (NH2OH)3H3PO4 → H3PO4 H3PO4 + base → Phosphate |
| Coefficient of Variation | 10% (for 20 to 600 ppm-hr) |
| Shelf Life | 2 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 | + | Reddish brown (Unclear demarcation) |
Other substance measurable with this detector tube
| Substance | Correction Factor | Measuring Range |
| Acetone | 0.7 | 1.4 to 420 ppm |
| Methyl isobutyl ketone | 2.0 | 4 to 1200 ppm |
| Acetaldehyde | 0.6 | 1.2 to 360 ppm |
| Calibration gas generation | Diffusion tube method |
| TLV-TWA | TLV-STEL | Explosive range |
| 200 ppm(2014) | 300 ppm(2014) | 1.7 to 11.4% |
采购中心
