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The rapid development of air filters is closely related to the development of military industry and electronic industry. In the first world war, the use of various chemical agents, asbestos fibre filter paper as the smoke filter layer of military gas masks came into being. The glass fiber filter medium is used in air filtration to obtain a patent in the United States in October 1940. In the 1950s, the United States studied the production process of glass fiber filter paper, and the air filter was improved and developed. In the 1960s, HEPA filters came out; In the 1970s, the filter paper of fine glass fiber was used as the HEPA filter of filter medium, and the filtration efficiency of particle size of 013 micron particle diameter was 99.9998%. Since the eighty s, with the emergence of new test method, use evaluation to improve and to improve the filtering performance requirements, found the HEPA filter there is a serious problem, and he had a higher ULPA filter performance. Countries are still working on it and expect more advanced air filters soon
Refer family and friends. In fact, talking about close friends and family often helps, as credibility of such information rises towards the extent of finding good deals. Besides, on the process, one eventually ends up finding genuine stores as well. In fact genuine stores charge less compared to ordinary stores. Most people are struggling to see this, because charges are greater than the ordinary stores. Thus, with a heuristic look, buying Audi Parts from authentic dealers after proper consultation with friends surpasses buying inferior parts at cheap rates. Often these inferior quality parts haven't any guarantee on the performance and life. Such parts tend to be more susceptible to wear and tear later on adding for the expense list.
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