Importance

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Abstract

A vacuum filter bag is constructed of layers which include a high air permeability multipurpose layer positioned upstream in the direction of air flow of a second filtration layer. The second filtration layer can be a wet-laid filter paper, a dry-laid filter paper or a spunbond nonwoven. The multipurpose layer can be made of high bulk meltblown nonwoven, dry-laid or wet-laid high dust holding capacity paper spunblown modular or microdenier spunbond. The high dust capacity papers are characterized by greater thickness and higher air permeability than is normally used in traditional filter layers of vacuum cleaner bag structures. These characteristics allow the high capacity papers to filter large dirt particles and to capture within their pores large amounts of dust particles. This protects the downstream second filtration layer from shock loading and enables the composite structure to pass air at high rate at low pressure differential for much longer than conventional vacuum cleaner bags. A method of filtering gas through such a filter is also disclosed.

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First Claim