本研究以流體力學的觀點，發展一氣簾阻截式生物安全櫃，並使用雷射煙霧流場可視化法、壓力診測法及雷射測速儀探討參數變化對流場狀態的影響，並以追蹤氣體濃度偵測方式來評估氣簾式生物安全櫃的洩漏，因而完成此一新型生物安全櫃之操作特性與範圍。將傳統生物安全櫃之櫃門改裝為可以提供一道二維吹氣噴嘴的機構，並於門檻背後設一道下吸式槽縫，當噴嘴與吸氣槽縫適當的運作時，可能使櫃門開口處形成一道空氣簾幕，以此來加強防護櫃內污染物不洩漏至外界的能力。為了瞭解生物安全櫃在運作時，櫃內及櫃門附近的流場型態，使用雷射光頁配合煙霧釋放流場可視化實驗技術進行流場診測研究，分析流場型態，推測造成櫃內污染物洩漏原因，並尋求可能的理想操作模態。吹氣速度、補氣速度、吸氣速度、櫃門開度等四項為影響氣簾式生物安全櫃流場的主要參數。由流場可視化實驗中，可以辨識出，氣簾的行為可以表現為(1)輕微內凹、(2)嚴重內凹、(3)筆直、(4)擺動模態四種特徵模態區域。當操作狀態使得氣簾特徵模態為輕微內凹模態時，櫃內與櫃外無迴流現象產生，且櫃內氣流非常平順的被導入門檻後之吸氣槽縫。另外，櫃內靜壓量測的結果得知，當操作狀態使得特徵模態為輕微內凹模態時，櫃內靜壓可以達到輕微低於外界壓力的狀態。基於過去對氣簾式化學氣櫃之研究經驗，這四種特徵模態中，輕微內凹模態可能會是最佳的操作區域。以追蹤氣體(SF6)模擬NSF/ANSI 49-2004生物安全櫃之微生物測試法，結果顯示，不論是人員防護測試、產品防護測試或交互感染防護測試，中心區域的輕微內凹模態都有非常優異的效能；以EN14175:3-2003穩態及動態追蹤氣體濃度測試後發現，中心區域的輕微內凹模態捕集效能也非常優異。以流場觀察配合濃度測量，結果說明中心區域的輕微內凹模態為氣簾式生物安全櫃最佳的操作區域；對一櫃門開口面積為1.3 m x 0.25 m的氣簾式生物安全櫃，操作於櫃外擾動激烈的環境下，所耗總風量僅需0.4 m3/s，相較於傳統B2型生物安全櫃而言，能源節省約13%。

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.

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