氮中微量水分气体标准物质的制备

Preparation of trace water vapor in nitrogen gas reference material

该文介绍一种高压瓶装氮中微量水气体标准物质的制备方法。气瓶经过加热高真空抽洗后,充入经过纯化器进一步纯化的高纯氮气,使用光腔衰荡光谱水分仪分析稀释气充装过程引入的水分。通过模拟露点曲线和冷却曲线确定使用环境温度≥5℃时的最大充装压力,分别使用普通铝合金气瓶和内壁特殊处理的铝合金气瓶,采用注射称量法,制备得到100μmol/mol的氮中水分气体标准物质,使用精密露点仪标准装置对其进行放压试验的考察。结果表明随着压力的降低,普通铝合金气瓶内水分量值变化明显,而内壁特殊处理的铝合金气瓶在使用过程中量值稳定可靠。

A method for preparation a high pressure cylinder gas reference material of water vapor in nitrogen at trace lever has been developed.The cylinders wrapped by heating jackets were totally evacuated and cleaned using a turbo molecular pump and filled with nitrogen,which was supplied from ultrahigh purity nitrogen cylinder and passed through a purifier,after that the water from dilution gas and filling process was measured by CRDs analyzer.The max filling pressure at ambient temperature≥5℃was confirmed through simulating dew-line and Joule-Thomson cooling curve,then 100μmol/mol gas mixtures were prepared in normal aluminum cylinders and passivation treated internally cylinders using injection-gravimetric method.The pressure release test was investigated by precision dew point hygrometer standard,which indicated that water concentration was changed obviously in normal aluminum cylinder while more reliable and stable in passivation cylinder.