一种新型动态配气仪研究

Study on a new kind of dynamic volumetric apparatus

目的研制一种将液配气和气配气合二为一的新型动态配气仪。方法当原料气在常温下为液态时采用扩散管法,利用减重称量法计算出物质在标准扩散管的扩散速率,以空气或氮气作为载气(稀释气),通过调节其流量即可得到所需质量浓度的标准气体;当原料气在常温下为气态时采用质量流量混合法,通过精确控制原料气和稀释气的流量,加以混合后得到所需质量浓度的标准气。结果研制的样机配置的标准气浓度可达到10-9级,最大稀释比达到1∶2 000。在液配气模式的动态配气应用测试中,其精密度测试结果显示相对标准偏差(RSD)<5.00%,已达到或超过日本同类产品水平;样机气配气模式应用的精密度测试结果显示RSD<5.00%,满足仪器设计要求。结论新型动态配气仪具有液配气和气配气合二为一的功能,稳定性较高,精密度好,能长时间连续稳定发生标准气体。

Objective To develop a new kind of dynamic distributing apparatus with combining functions of fluid distribu- tion and gas distribution. Methods The method of diffusion tube was used when raw material gas was a liquid at normal temperature. The diffusivity of a material in the standard diffusion tube can be obtained by weighing method of weight loss, in which air or nitrogen was used as a carrier gas and to get the required calibration gases by adjusting the rate of flow. The method of a mixing mass flow was used if the feed gas was gaseous. A certain concentration of calibration gases required could be obtained by accurate controlling the flow of feed gas and dilutes. Results The concentration of the calibration gases of the apparatus reached 10 -9 and the dilution ratio was up to 1 ： 2 000. Fluid distribution mode of dynamic distribu- tion application tests showed that its accuracy had reached or exceeded the level of similar products in Japan, the relative standard deviation was less than 5.00% ; gas distribution mode of dynamic distribution application tests showed that the relative standard deviation was less than 5.00%. The experiment showed that the developed prototype could meet the needs of the design. Conclusion This apparatus with dynamic volumetric method has developed two functions in one. Compared with the conventional and similar products, the prototype not only has high stability and accuracy, but also can supply standard gas continuously and stably for a long time.