The study of capture efficiency for local ventilation hoods with trace gas

• Main Authors: Kai-Chun Cheng, 鄭凱駿
• Other Authors: Cheng-Ping Chang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/81330690650081962277

碩士 === 長榮大學 === 職業安全與衛生學系碩士班 === 103 === The major effort of fume hood is that locked the contaminants in the cabinet, and pushed it out through the exhaust duct. Currently common testing methods for the fume hood performance are trace gas methods, such as: EN14175-3: 2003, ASHRAE110, because the methods used SF6 as the trace gas, it takes a long time to evaluate the leakage of the fume hood, and release lots of trace gas. The global warming potential (GWP) of SF6 is up to 22,800 times higher than CO2, So we have to find new ways to reduce the release amount of tracer gas SF6, and the rapid way to elevate the performance of the fume hood. The purposes of this study are 1. Establish a evaluate method of fume hood performance with SF6 as trace gas. 2. Establish a evaluate method of estimate the total capture efficiency from the duct’s concentration. 3. Measure the fume hood face velocity and find the correlation of the air flow pattern with face velocity. 4. Use of the European test method (EN14175) and total capture efficiency to evaluate the performance of the 2 different type fume hoods (traditional and air curtain type) , and find out the relationship of 2 methods. According to the above principles, this study using EN14175-3: 2003 tracer gas (Trace Gas Measurement) static mode as one of the test method, this method to set the 6 measurement points of the fume hood open face, and then release the mixed gas with 1/10 SF6 of 2L / min flow rate, and grid-like surface of the sampling probe is placed in the setup measurement points, observe the concentration distribution. Under the same conditions, the sampling probe is placed at the center of the duct to measure the concentration and to estimate the capture efficiency. The measurement instrument is the portable infrared spectrometer (InfraRan), the concentration will be analyzed through the enclosed chamber (Close Cell) from the probe. Traditional fume hood and air curtain fume hood in accordance with the method using SF6 as a tracer gas, each data measured three times, test results showed that the higher the concentration of its counter leakage is more likely to be relevant. Although this new method is not very sensitive, but it is an inexpensive and fast fume hood performance evaluation method, which can spend less time and cost than EN14175method.