US 5,507,847 A · ULPA filter

Abstract

An improved filter unit suitable for use in a variety of clean air filtration applications is taught. The filter unit employs continuous microporous filtration membranes, such as expanded polytetrafluoroethylene, to deliver exceptional filtration efficiencies on the order of 99.99999% at 0.1 .mu.m with minimal pressure drop produced across the filter. Additionally, the filter unit of the present invention has the further advantage of avoiding many previous deficiencies in HEPA and ULPA filter units, such as filter contamination from shedding particles and/or out-gassing, and limitations on chemicals to which the filter can be exposed without deterioration. As a result, the present invention provides a cleaner and more durable filter that can be used to address growing contamination problems in many different industries, such as electronics and pharmaceuticals.

Claims20

Dependent claims

A filter for use in air conditioning systems in clean facilities which comprises:

a primary filtration layer of microporous polytetrafluoroethylene (PTFE);
at least one upstream layer of permeable support material;
at least one down stream layer of permeable support material, the filtration layer being loosely sandwiched between the upstream layer and downstream layer of support material;
wherein the primary filtration layer and the support materials combine to provide a filtration efficiency of at least 99.97% at 0.3 .mu.m and less than 1 inch water pressure drop at 100 ft/min air velocity.

1 more element

Dependencies are inferred from the claim text.

ULPA filter

Life of this patent

ULPA filter

Life of this patent

Abstract

Claims20