落地型斜氣簾式排氣櫃性能評估

Performance Evaluation of an Inclined Air-Curtain Walk-in Fume Hood

斜氣簾式排氣櫃在櫃底工作面上加上一道上吹二維氣流，並在左右側牆內安裝一片直立的長型導流板，配合狹縫形上吸式氣罩，使櫃內形成一道傾斜的空氣簾幕，配合上吹噴流吹氣速度、吸氣槽吸氣速度與其它參數，能有效將污染物控制在氣櫃內部。本研究用數種方法來評估斜氣簾式設計應用在落地型排氣櫃上。使用面速度量測法量測不同櫃門開口度下面速度分佈情形以及其平均面速度。在prEN 14175-3：2003內部量測面示蹤氣體測試結果顯示，在櫃門開度H=50cm時，p1~p8八個區塊的平均洩漏率小於0.005ppm，瞬間最大洩漏值為0.027ppm。本研究中使用自行設計的示蹤氣體釋放器搭配採樣探頭進行開口逸散模擬量測，在10cm至25cm的開口高度下，示蹤氣體SF6洩漏濃度全程小於0.005ppm。在H=30cm 及35cm，僅出現瞬間峰值0.011ppm及0.010ppm，平均值仍小於0.005ppm。櫃門開關動作洩漏測試中，當釋放器高度Hej=60cm，櫃門H從20cm開至100cm，其階段平均SF6洩漏濃度為0.093ppm。瞬間峰值為0.280ppm。改變吹氣槽吹氣速度的櫃門開關測試結果Vb=1.7m/s，Cavg=0.056ppm；Vb=0.7m/s，Cavg=0.115ppm；Vb=0.2m/s，Cavg=0.179ppm。當Vb越大，櫃門開關動作時的整體洩漏率越低。強健度測試結果中，吹氣速度Vb=1.7m/s時的強健度干擾測試SF6洩漏平均濃度0.041ppm亦優於Vb=0.7m/s下的0.155ppm。綜合上述結果，適當的吹氣速度能有效將污染物控制在氣櫃內。

The inclined air-curtain (IAC) fume hood employed in the present work was constructed with the cross-flow fan at the bottom, deflection plate along the side walls, and a suction slot at the top of the cabinet. The containment in the cabinet was controlled effectively by using the two-dimension blow velocity and suction velocity. A research of an IAC walk-in fume hood performance was operated in several methods. Face velocity was measured at different sash opening to know the distribution and it’s average face velocity. The mean leakage SF6 concentration is less than 0.005 ppm at p1~p8 block by inner test method based on EN14175-3. The peak concentrations are 0.027 ppm. The tracer gas concentrations are less than 0.005 ppm in 10 cm,15 cm, 20 cm and 25 cm sash opening by self-develop method. The average concentration are less than 0.005 ppm, peak concentration are 0.011 ppm and 0.010 ppm at 30 cm and 35 cm sash opening. The average concentration of SF6 is 0.093 ppm, peak concentration is 0.280 ppm at Hej=60 cm, H=20 cm~100 cm sash movement test. The tracer gas test results in different blow jet velocity were as below: Vb=1.7 m/s, Cavg=0.056 ppm; Vb=0.7 m/s, Cavg= 0.115 ppm; Vb=0.2 m/s, Cavg=0.179 ppm. Robustness test results were: The average concentration is 0.041 ppm when Vb is 1.7 m/s. The average concentration is 0.155 ppm when Vb is 0.7 m/s. When the blow jet velocity (Vb) decreased, the containment efficiency also reduced at sash movement test and robustness test. This result showed that an adequate blow jet velocity would provide a higher containment performance.