Albemarle undertakes strategic review of catalyst business

Abstract

Nanoparticles (NPs) are particles of less than or equal to 100 nm in diameter. Due to their size, they have a significant effect on health and safety of people. Capture of these NPs in general ventilation systems by filters remains one of the most widely used means of protection due to its relative simplicity of implementation and its effectiveness for capturing various size of particles. In North America, filters used in general ventilation systems are tested by the ANSI/ASHRAE Standard 52.2 and are graded according to their efficiency, which is a function of particle diameter. However, the current standard limits the filtration efficiency assessment for particles between 0.3 and 10.0 µm. There is therefore a significant lack of knowledge about the behavior of these filters with respect to the particle diameter below 0.3 µm considering the overall filter used in general ventilation. The main objective of this study was to develop a measurement procedure to evaluate the effectiveness of mechanical filters used in general ventilation systems against NPs. In this regard, a small setup was designed, build and qualified. Then measurement procedure was validated by comparing the penetration measurements with those obtained on qualified big loop setup for nanoparticles, which was inspired by ASHRAE. One type of mechanical filter rated (MERV 8) in three depth sizes (2.54, 5.08 and 10.16 cm) was used to compare the penetrations. The obtained results are consistent with the classical filtration theory for mechanical media and with previous experimental measurements on media. The data presented in this study show that the penetration range of 0.7–1.0 obtained for particle range 22.1–294.3 nm and at 1.00 and 0.75 m/s gives a fairly good correlation (R2 = 0.898) between the two setups. The outcome results validate the methodology used to evaluate the effectiveness of one mechanical filter used in general ventilation systems against nanoparticles by using the small setup.