Absolute HEPA filters have low emissions of sensory pollutants after extensive use under realistic conditions. But we still need to know how to design Absolute HEPA filters so that we can create better versions of filters. Due to this reason, a range of sensory evaluations are performed for eight Absolute HEPA filters or filter combinations. To be more specific, the combinations of filters have included either pre-filters or carbon filters. Each filter or filter set has to be soiled under identical service conditions in the first place so the comparison is meaningful in the end. By doing so, we can achieve lower emissions of sensory pollutants from used Absolute HEPA filters. That would have the potential to improve air quality as well as to reduce healthy symptoms. At the same time, we can increase performance with only a modest increase in operating costs as long as we know how to design absolute HEPA filters. However, these types of filters are very expensive even though they can generate high pressure drops. They also have limitations in capturing particulate matters of very small sizes. That is why metal filters and Absolute HEPA filters have been studied as possible solutions in practice. However, the corrosion of the metal at high temperatures is of great concern in many industries. In fact, it has to be admitted that the high production costs of these filters make these options less desirable as well. Also it is generally known that the Absolute HEPA filters are heavier and generate higher backpressures than monolith filters.
The desired inlet concentration can be adjusted by a needle valve at the outlet of a standard cylinder if we know how to design absolute HEPA filters. Excellent filtering performance can be achieved through mixing the elements in an air blower. Four sampling ports are located along the filter for gas sampling and pressure measurements at the same time. The leftmost port is regarded as the inlet sampling port inside Absolute HEPA filters and the other three as outlet sampling ports in the same vein. The filtering pressures at different sampling ports are accurately measured using a manometer with a minimum reading in the column. What is more, samples inside Absolute HEPA filters will be taken periodically for measurement, chemical analysis and viable bacterial counts according o tips on how to design absolute HEPA filters. The system should be operated at room temperature throughout the entire filtering process. On the other hand, Activated Carbon Filters can effectively remove selected organic pollutants from airstreams at a relatively lower cost. Therefore, the use of activated charcoal filters is also an economically viable approach for those users who are on a tight budget.
