Design And Evaluation Of An Aerosol Generator For Testing High Efficiency Particulate Air Filter

With the rapid development of modern industries such as electronic, medical, precision instrument, aerospace, control of airborne particles becomes more strict both with particle size and number, and the requirement for the performance and quality of high efficiency particulate air (HEPA)filter becomes higher and higher. So, it requires advanced testing method to guarantee the HEPA filter's performance and quality. Particle counting method is one of the testing methods for HEPA filter, because its advantage of high sensitiveness, this method has become international leading testing methods for HEPA filter, which adopted by most European and American countries. In China, the testing methods for HEPA filter are Sodium Flame method and Oil Mist method. These methods haven't revised more than ten years and already don't reach the practical needs. For the sake of accelerating the development of our country's air filter industry and upgrade its product quality, the revision of national standard------methods for testing the performance of high efficiency particle air filter has been started in 2005, and it is necessary to study the particle counting method. To study this method, one of the most important tasks is to generate the required test aerosol, that's mean to develop an aerosol generator which is able to generate the required test aerosol.Therefore, in this paper, the require performance of the aerosol generator is studied firstly, referring the review of many exiting filter testing standard -s over the world, and then, based on the analysis and comparison of many aerosol generate technologies, condensation method is introduced in the design of this aerosol generator. Secondly, in order to understand the aerosol generator's design, the principles of the condensation method are studied deeply, and based these principles, the design and manufacture of this aerosol generator is accomplished. Lastly, a series of experiments are taken on this designed aerosol generator and its operation parameters are investigated systematically.The experiment results show that the designed aerosol generator is able to produce discrete particle diameter of 0.1 to 0.3 micrometers at high concentration output rate of 10¹¹ particle/min with a geometric standard deviation (GSD) about 1.3, which is defined as a quasi-monodisperse according to European Standard EN-1822. The experiment results also show that the design objective of this aerosol generator is achieved. The research results are helpful to the revision of China's national standard------methods for testing the performance of high efficiency particle air filter. It is also useful in design of (quasi- monodisperse) monodisperse aerosol generator.