Polyester, being a "commodity" fiber, is available in a significant range of deniers (effectively diameters) and so a wide range of filter media products can be designed to match the demands of the filter; from very high collection efficiency (with very fine fibers) to low efficiency products (using coarse fibers) where flow is more important than collection.
A wide variety of chemical and thermal treatments are available for polyester, the most common being super glaze to improve dust release and liquid repellency to assist with sticky dusts.
Warp Tensile Strength
Weft Tensile Strength
Singed, smooth, stabilization
Oxidization Agents Good
Avoid strong alkali and acid environments at elevated temperatures – the most versatile of the low temperature fibers, used in the cement and quarry, metal processing, flour and wood industries.
Finishing :heat set
When fibers are manufactured they invariably have a residual tendency to shrink in length when heated substantially. After these raw materials are converted to filter felts, they need to be heat stabilized to ensure that any shrinkage in the final application is minimized.
There are a number of ways of achieving this, but in essence, all require that the filter media is exposed to a temperature comfortably above the expected operating temperature. The material has then has to be held at that temperature to ensure that the in-built stresses are relaxed out.
The result is a stabilized filter media which will exhibit minimal shrinkage at the anticipated operating temperature.