扩散管配制甲醛标准气体的研究

Generation system of formaldehyde standard gas by diffusion tube

介绍了扩散法配制标准气体的方法。以三聚甲醛为原料，通过加热催化分解三聚甲醛蒸气，来配制甲醛标准气体。讨论了配制甲醛标准气体的准确性、稳定性、重复使用性，以及温度、扩散管几何尺寸、载气气流、配气源物质的量等因素对三聚甲醛扩散率的影响。本方法制备的甲醛标准气体，扩散率（２～５０μｇ／ｍｉｎ）测定总不确定度小于５％。

A simple, reproducible generation system of formaldehyde standard gas by diffusion tube has been developed.Formaldehyde gas was produced by catalytic thermal depolymerization of trioxane vapor generated from diffusion tube. The precision, accuracy, reproducibility and factors of effect(e.g temperature, the geometry of diffusion tube, the flow of carrier gas and quantity of trioxane in the tube)on HCHO gas generation rate have been discussed.The total uncertainty of HCHO generation rate(2～50 μg/min)is less than 5%.