- 學位論文
標準氣體產生系統穩定性評估
Evaluate the stability of standard gas generation system
摘要
本研究是為了建立能產生穩定濃度、穩定流量之標準氣體產生系統，測試不同參數下對系統之影響如:稀釋次數、環境溫度、載流氣體流量、配製濃度，並利用光離子氣體偵測器對該系統產生之氣體濃度穩定性進行評估。 第一次實驗測試了二次稀釋、預估濃度對系統濃度的影響評估，該實驗中環境參數固定為25℃、1atm的標準環境，第二次實驗測試了環境溫度、載流氣體流量、預估濃度對系統濃度的影響評估，在本研究中以變異係數與RPD來判別標準氣體產生系統的準確性與再現性。 此標準氣體產生系統為注射針筒驅動法(calibration syringe drive method)，注射針筒驅動式主要是利用注射針筒定速注射液態的揮發性有機溶劑進入揮發腔，而產生固定濃度之氣體，此時再以乾淨之載流氣體將此固定濃度之揮發物帶至混合腔，混合均勻後之標準氣體再流至採樣腔，進行採樣。 台灣一般室溫範圍的環境溫度對標準氣體產生系統濃度的穩定度影響不大，而低濃度的配置與低流量的載流氣體對穩定度是好的，但這些變數下與預估配置之濃度差異上偏高，所以本系統在低濃度與低流量下為濃度與預測值偏高但再現性亦高，若經由修正值後會是一個可用的標準氣體產生系統。
並列摘要
This study is to establish a standard gas generation system with stable concentrations and steady flows. The system use different parameters to the test as: dilution conditions, ambient temperature, carrier gas flow. This test use photoionization detectors to measure the gas concentration. The first experiment tested for the influence of double dilution system, environmental parameters in this experiment is fixed at 25 ℃, 1 atm. The second experiment tested for the influence of the ambient temperature, carrier gas flow and concentration. In this study, use the CV and RPD to determine the standard system accuracy and reproducibility. This standard gas generation system is the syringe driver method (calibration syringe drive method), a syringe driven method mainly use fixed speed syringe injection liquid volatile organic solvents into the volatilization chamber, to generate a fixed concentration of the vapor. Then the clean carrier gas carried the high concentration gas into the mixing chamber, 2 streams of gas well mixed in the chamber, then sent it into the sampling chamber for testing. The temperature range of room temperature on the standard gas generation system did not interference the stability of the system. And the stability of the system at low concentrations and low carrier gas flow rate condition are better than others. There is a systematic error on the system, the concentrations got from the system are proportional lower than the estimate value. But, there are good reproducibilities at low concentrations and low-flow rate, the data of the system can be modified by a correction factor and get a acceptable result.