The study of Chemical hood performance with different tracer gas

• Main Authors: Yu-En Chang, 張宥恩
• Other Authors: Cheng-ping Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/56382415806088885967

碩士 === 長榮大學 === 職業安全與衛生學系碩士班 === 101 === The effort of fume hood is that induce the clean air into the hood, hold the containment air in the hood and exhaust the containment air by the pipe. The test method ASHRAE110 and EN14175-3:2003 use the SF6 as the trace gas to test the performance of the fume hood, but the greenhouse effort is more and more serious in recent years, and the SF6 is one of the 6 gases of EPA’s plan to reduce emissions of greenhouse effect gas, its global warming potential is 22,800 times greater than that of CO2.The study aimed to follow the test method EN14175-3:2003 is using different specific gravity tracer gas to evaluate contaminant leakage for fume cupboard. Observed behavior patterns of different tracer gas, it’s possible replaced sulfur hexafluoride. Compared with different leakage pattern for conventional fume cupboard and Air-Curtain Fume upboard. The choice of alternative gas should have the same physical and chemical properties of sulfur hexafluoride, Global warming potential (GWP) is lower, low toxicity and non-flammable for safety consideration. According to principal of selections above, the environmentally friendly refrigerant R-134a is an ideal alternative gas, which will compare with the sulfur hexafluoride as a trace gas and follow the test method EN14175-3:2003. There are 3 major parts of this method, first, measured the velocity in each points of the fume cupboard, and then release a mixed gas of 2 l/min flow rate and the sampling probe grid shall be positioned a specific location in the sash opening of the fume cupboard, observed concentration distribution. A close-cell portable infrared spectrometer is used to analysis the concentration of trace gases. For the same fume hood, according to EN-14175 method, there are three times of each test with the same concentration of SF6 and R134a. The result showed that the R134a is more singnificance. For the environmental protection and cost, testing one hundred thousand fume cupboard is equal to cut one hundred seventy million tree for carbon emissions per sulfur hexafluoride. The cost is needed one hundred thirty million dollars; if using R134a as a substitute about seventy-five million tree, the cost is eight point seven five million dollars. The results showed that the R-134a is suitable to alternative sulfur hexafluoride as a trace gas, its low toxicity, non-flammable characteristic in quite suitable for the test method.