Abstract: A pleatable and cleanable filter media (22) that has a HEPA filtration rating. The filter media (22) includes a porous primary filtration layer (22). The primary filtration layer tending to be less than HEPA rated upon being damaged. A first substrate layer (64) attached to said primary filtration layer (62) for maintaining the shape of the filter media (22). The first substrate layer (64) includes a non-woven filtration media and being less than HEPA rated. A second substrate layer (82) attached to the first substrate layer (64) functioning as a secondary filter in the event of damage to the primary filtration layer (62). The second substrate layer (82) includes a non-woven filtration media and being less than HEPA rated.

Abstract: A filter element is adapted to be located in a gas stream. The filter element comprises a substrate having a structure selected from the group consisting of scrimed needled felt, scrimless needled felt, woven fabric and mesh. The substrate comprises at least two different materials. A first one of the materials has a first melting temperature. A second one of the materials has a second melting temperature lower than the first melting temperature. An expanded polytetrafluoroethylene filtering membrane is adapted to be located upstream relative to the substrate in the gas stream and supported by the substrate. The substrate is attached to the filtering membrane by the second material of the substrate melted to engage the membrane and fix the membrane to the substrate.