Determination of pore structure characteristics of filtration cartridges as a function of cartridge length

Test apparatus for using a flow porometer to determine pore structure characteristics of at least a portion of a filtration cartridge, comprising a porometry test location isolating device having means for directing flow of a pressurized test gas through only a preselected test location along the length of said filtration cartridge, means for applying pressure in small increments to said test location, means for measuring differential pressures of said test gas, and means for measuring a rate of flow of said test gas through said test location, wherein said test location isolating device is selected from the group consisting of inserts, rings, and sleeves that slidingly engage either an inner or outer surface of said filtration cartridge and direct said test gas through said test location of said cartridge, said insert comprising:

• a) a tubular member having a test gas inlet at a first end thereof and a sealed second end;
• b) a plurality of radial gas channels arranged between said first and second ends of said tubular member for directing flow of said pressurized test gas through said tubular member to said preselected test location of said cartridge;
• c) a pair of O-rings seated within a pair of circumferential O-ring grooves arranged between said radial gas channels and said first and second ends of said tubular member, said O-rings defining said test location and confining flow of said pressurized test gas through said test location;
• and
• d) a pair of flexible members attached to said ends of said tubular member for pulling said insert through a filtration cartridge having an irregular shape or a bent or deformed cartridge.