Zitex® A Filter Membranes

Manufactured by a unique process which produces pure PTFE replicas of various media, Zitex A is available in a number of various filter porosities and thicknesses.  It is commonly supplied in 12 in. wide rolls with continuous lengths up to 100 ft. long.  Zitex A can withstand severely corrosive conditions at temperatures between +550°F (+228°C), and -450°F (-268°C), making it the ideal solution for a variety of engineering problems in the chemical, electrical, packaging, filtration, medical and aerospace industries.

Pore Geometry

http://www.norton-films.com/uploadedImages/SGNortonFilms-NA/Images/Zitex/ZitexA.gifZitex A filter membranes are reproductions of standard filter papers and consequently have the same tortuous, fibrous filter paths.  The membranes act as "depth filters" with high retention efficiency and non-clogging characteristics.

Unlike cellulos filter paper, however, the PTFE interstices are bonded together.  The resulting pore size stability allows Zitex to act as an "absolute" filter.  This unique combination of depth and screen filtering ability means Zitex is a more effective filter membrane medium.

Data shown are representative and not to be used as material specifications.
(1)  A = Gallons/minute/ft² @ 13.5 psi., B = Ml/minute/cm² @ 70 cmHg.
(2)  Time required for 100cc to pass through 1 square inch @ Δ P 0.176 psi (Gurley test).
(3)  Pressure differential necessary to overcome hydrophobic and internal resistance.

Zitex® G Filter Membranes

Zitex® G exhibits the same unique characteristics as Zitex® A and also has very high water retention pressures, making it the logical choice where a highly reliabile hydrophobic vent is required.  Two other properties that make Zitex G ideal as an air-PTFE dielectric for miniature coaxial cables are tensile strength and elongation, which allow easier wire wrapping without fear of breakage.  Zitex G is approximately 50% air by volume and thus provides unusually good dielectric characteristics.  For instance, Type G-106 has a dielectric constant of 1.5 and a dissipation factor less than .00022 at 10GHz.  Zitex G is also available in perforated form with 46% open area.

http://www.norton-films.com/uploadedImages/SGNortonFilms-NA/Images/Zitex/ZitexG.gifStrong and tough, Zitex G can be installed in membrane holders without the need for non-PTFE polymeric backings, so there's no compromising on properties that might be important to your application.

Particle retention is also very high, especially when filtering air and other gases.

On the subject of liquid filtration, Zitex G again stands out from the crowd.  Liquids may be filtered by using pressures exceeding the membrane's water initiation pressure, or with the aid of wetting agents such as ethanol.

Zitex® G materials are available in thicknesses up to 0.25".  These materials are ideally suited for gasketing applications where a compressible liner is required.  These gaskets are ideal for glass-to-glass fittings, or where non-uniform sealing areas are involved.  Contact us for these custom products or special formulations.  Zitex G can be produced in thicknesses greater than .015".