Method and apparatus for the leak testing of filters

An apparatus for filtering an airstream and having provision for testing for leakage of particles of predetermined size through or around the filter, and characterized by the ability to substantially uniformly disperse the particles across the entire area of the upstream face of the filter from a point relatively close to the filter to thereby minimize the space requirements of the apparatus, and comprising

• a housing adapted to form a part of an air duct system having an airstream passing therethrough,
• means for sealably mounting a filter within the housing such that the airstream passing through the housing passes through the filter,
• means for introducing particles of predetermined size into the airstream within the housing and immediately upstream of the filter, and including means for imparting a like electrical charge to the particles such that the particles repel each other and rapidly disperse within the airstream, and
• means for detecting at least a portion of any particles further downstream of the filter to thereby permit a determination as to whether any of the particles are leaking through or around the filter.

An apparatus for filtering an airstream through a bank of filters and having provision for testing for leakage of particles of predetermined size through or around any of the filters and characterized by the ability to permit the immediate identification of a leaking filter in the bank, and comprising

• a housing adapted to form a part of an air duct system having an airstream passing therethrough,
• means for sealably mounting a bank of filters in a parallel arrangement in said housing such that the airstream passing through the housing passes through the bank of filters,
• panel means mounted within said housing and immediately upstream of the bank of filters for dividing the housing into a separate air channel for each of the filters, and such that the airstream is divided into an isolated portion within each of the separate channels which passes through a single filter,
• means including an outlet nozzle mounted centrally within each of said separate channels for selectively dispersing particles of predetermined size into the portion of the airstream passing through any one of the channels, and
• means mounted within said housing and downstream of said filter bank for collecting at least a portion of any particles in the airstream to thereby permit a determination as to whether any of the particles are leaking through or around any of the filters in the filter bank.

An apparatus for rapidly and substantially uniformly dispersing particles of predetermined size into a moving airstream, and comprising

• an elongate tubular member adapted to be disposed in a direction parallel to the direction of the airstream, said tubular member having a plurality of openings extending radially through the wall thereof, and with the openings extending in a plurality of radial directions,
• a circular metal ring,
• means for mounting said ring in a coaxially disposed, radially spaced apart relationship about said tubular member,
• means for introducing the particles into the tubular member such that the particles exit through the radial openings into the airstream, and
• means for imparting an electrostatic charge to said ring such that the particles exiting through the openings of the tubular member receive an electrical charge of like polarity and the particles repel each other and rapidly disperse within the airstream.

An apparatus for testing for leakage of particles of predetermined size through or around an air filter, and characterized by minimum space requirements, and comprising

• a housing of rectangular cross-sectional configuration and having four side walls,
• means for sealably mounting a filter within the housing such that an airstream passing through the housing passes through the filter,
• means for introducing particles of predetermined size into the airstream within the housing and immediately upstream of the filter,
• means for selectively condensing the airstream immediately downstream of the filter, and
• means for withdrawing a sample of the condensed airstream to permit an analysis of the same and thereby determine whether any of the particles are leaking through or around the filter.