Chemical Treatment of Felts

These finishes can considerably improve a felts performance, efficiency, and life expectancy.

Treatments can be applied either by impregnation, where all the fibers are individually treated, or by coating, where only the filtration surface of the felt is treated. Also a combination of impregnation and coating can be done.

"Olephobic" "Hydrophobic"
This treatment is applied via an impregnation process to impart some water or oil repellency properties to the filter media. Every fiber is treated with a fluorocarbon based resin which assists in releasing a wet, oily or sticky dust cake during cleaning. Another, very common use for a felt with a fluorocarbon treatment is in applications where there is a high risk of hydrolysis attack. This is generally caused by the baghouse temperature falling below the dewpoint temperature (temperature at which the gas condenses into a liquid). Here the treatment provides some chemical resistance.

This is also an impregnation treatment which is applied to all the fibers. The presence of the silicone considerably reduces any cake cleaning problems associated with sticky, agglomerating dusts. Usually, a silicone treatment is less expensive than fluorocarbon.

Acid Resistance
Polyester and Aramid fibers are susceptible to attack by moisture particularly in the presence of acids. This is an impregnation treatment that "sheaths" every fiber in a chemically inert fluorocarbon resin that retards the destructive chemical attack on the fiber, the result being an increase in product life.

Flame Retardant
The design of some filter systems can cause hot incandescent particles to be carried in the dust stream over to the baghouse and onto the filter bag. In extreme circumstances these particles can ignite the media and cause a fire in the baghouse. More commonly, they cause minor damage such as pinholes, which leads to excessive emissions and premature bag failure. This treatment is applied via impregnation and each fiber is individually protected against the hot particles, hence prolonging bag life.

Acrylic Foam Coating
This is a coating of porous acrylic foam which is applied to the felt surface to effectively simulate an instant dust cake. Via effective control of the foam cell "bubble" structure a very uniform pore structure is applied to the filtration surface. The benefits of this type of coating include improved filtration on the felt surface as well as improved filtration efficiencies without incurring increased filter pressure drop.

Evaluating This is a special new polyurethane foam coating applied exactly the same as the acrylic coating, giving similar performance attributes. However, the Dura-Shield coating also imparts improved temperature resistance and coating toughness properties over the acrylic product.

PRFE Foam Coating
This is a micro-porous surface coating of a PTFE based foamable resin. The PTFE coating imparts two distinctive advantages. Firstly, the coating improves the surface filtration efficiency; and secondly, the PTFE resin reduces cake build-up of agglomerating, strongly adhesive "tacky" dusts. This enhances cleanability and reduces the risk of premature blinding of the filter.