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 |