Flow and Leakage Characteristics of Air-Curtain Biological Safety Cabinet

• Main Authors: Chun-yi Chou, 周峻儀
• Other Authors: Rong-Fung Huang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/28329643907208324872

碩士 === 國立臺灣科技大學 === 機械工程系 === 96 === This is an experimental study on the applicability of air curtain isolation technique to enhance the containment of the biological safety cabinet. To provide a two-dimensional slot jet, the sash was remodeled and a suction slot was installed just behind the doorsill. This arrangement provides an air-curtain based on the push/pull principle which covers across the sash opening. Laser-assisted flow visualization method, laser Doppler velocimetry and in-cabinet pressure measurements were carried out to identify the characteristic flow modes of the air curtain and the pressure variation in the biological safety cabinet. Four characteristic flow modes were identified namely, slightly concave curtain, severely concave curtain, straight curtain, and oscillating curtain. A slightly concave curtain shows a stable flow field and a smooth flow pattern in the cabinet. The prominent feature is that no recirculation flow structures were found. The in-cabinet pressure measurements show slightly negative pressure appearing in the cabinet when the biological safety cabinet was operated in the regime of slightly concave curtain. Previous work suggested that, operating the cabinet in the regime of the slightly concave curtain can be a good choice to attain high containment efficiency and low leakage level. Performance test of the air-curtain biosafety cabinet was conducted through tracer-gas concentration measurements which simulate NSF/ANSI 49-2004 standard method. Extra-ordinary and satisfactory results were obtained from the said tracer-gas concentration measurements. EN14175-3 standard methods were also employed to test the performance of the air-curtain biosafety cabinet under both the static and dynamic situations, where leakages of the tracer gas approach almost null. The measured tracer-gas concentrations results agree with the observed flow patterns. For an air-curtain biosafety cabinet with opening area of 1.3 m x 0.25 m and operating in a hostile environmental, the total flow rate would be 0.4 m3/s. It is about 13% less than that of the conventional type B2 biosafety cabinet.