Self-Support vs Scrim Support
Advancements in technology have now made possible a fiber supported felt that is equal to and, in most cases, has better performance characteristics than traditional scrim supported felts. Here is additional information and specifications:
- The absence of a scrim means that all of the fibers in the felt are available for filtration. Scrims are so tightly produced that they cannot contribute to normal filtration.
- Scrims can blind easily if dust penetrates into the felt. This can lead to premature failure of the bags from the resulting high pressure differential.
- The absence of a tight scrim means that air can flow more freely, allowing higher velocity or lower pressure drop.
- Scrims affect the flexing characteristics of the felt, so their removal can improve some aspects of the media’s behavior, including allowing easier pulse cleaning.
- Needling tends to weaken scrims, whereas this process strengthens fibers. In most cases this leads to higher overall media strengths.
- In general, fiber supported felts are less expensive than those containing scrims, due to the high cost of producing scrims.
In terms of physical characteristics, the products compare as follows for a 16 Opsy polyester felt:
|Fiber Supported||Scrim Supported|
|Mullen Burst||540 PSIG||400 PSIG|
|Permeability||40 CFM||40 CFM|
|Average lbs of force at failure (Longitudinal)||236.5||223.7|
|Average lbs. of force at failure (Lateral)||413.3||291.6|