Test methods for evaluating the filtration and particulate emission characteristics of vacuum cleaners.

The overall filtration efficiency of a vacuum cleaner traditionally has been tested by placing the vacuum cleaner in a test chamber and measuring aerosol concentrations at the chamber inlet and outlet. The chamber test method was refined and validated in this study. However, this chamber test method shows an overall filtration efficiency of close to 100% for most of the industrial vacuum cleaners and for most of the newly developed household vacuum cleaners of midprice range or higher because all these vacuum cleaners have a high-efficiency particulate air (HEPA) or other highly efficient filter installed at the exhaust. A new test method was therefore developed through which the vacuum cleaner was probed in various internal locations so that the collection efficiency of the individual components could be determined. For example, the aerosol concentration upstream of the final HEPA filter can thus be measured, which permits one to estimate the life expectancy of this expensive component. The probed testing method is particularly suitable for field evaluations of vacuum cleaners because it uses compact, battery-operated optical particle size spectrometers with internal data storage. Both chamber and probed tests gave the same results for the aerosol filtration efficiency. The probed testing method, however, also gives information on the performance of the individual components in a vacuum cleaner. It also can be used to determine the dust pickup efficiency and the degree of reaerosolization of particles collected in the vacuum cleaner.