Are all filters made with HEPA filter media HEPA filters?
Manufacturing a filter with HEPA filter media does not mean that the filter itself meets true HEPA efficiency requirements. Serious filter leakage can go undetected if filters are not individually tested and certified at the end of the manufacturing process. Even the tiniest pinhole leaks in the media or breach of the seal between the media pack and the filter frame can cause the filter to fail IEST requirements. The testing requires very specific procedures using a thermally generated mono-dispersed aerosol and a laser particle counter. Some regulations also require field-testing by the user prior to going into service and periodically thereafter.
