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1) Fabric Selection

Media performance is a function of fiber properties, fabric construction, and fabric finishes.

HL Filter’s extensive knowledge and experience of how these variables interact allows us to determine the most effective filter media solution to meet your requirements related to flow rate, filtrate clarity, product dryness, cake release, and resistance.

Because each baghouse has its own set of characteristics and system parameters, it is important to evaluate each of the following variables in order to choose a fabric best suited to the system:

- Temperature - do your bags need to withstand extreme temperatures?

- Product/Particulate size - what are you filtering?

- Humidity-what moisture conditions within which the filters must withstand?

- Chemistry - can your bags withstand the chemical make up of the dust particles?

- Resistance- is the filter media able to resist the wear and tear of the dust particles?

- Air-to-cloth ratio

- Particulate abrasiveness

- Mechanical factors, such as cleaning style, installation, etc.

1.1 Fiber Properties

Fiber Characteristics

Fiber Max. Continuous Temperature () Max.  Surge Temperature
Tensile Strength Resistance Sypport Combustion Special Properties
Abrasion Moist Heat  Acid Alkaline
Nylon (PA)     Excellent         Yes  
Polypropylene (PP) 194 (90)   230 (110) Excellent Very Good Excellent Excellent Excellent Yes Excellent cake release.  Lowest temperature
Acrylic  260 (127) 284 (140) Fair Good Excellent Good Fair Yes A type of acrylic, functions at higher temperatures 
Polyester (PE) 265 (130) 302 (150) Excellent Excellent  Poor Fair Fair Yes Most versatile, cost effective, and widely used
PPS 374 (190) 392 (200) Very Good Good Good Excellent Excellent No Excellent chemical resistance (except for oxidation)
Aramid (Nomex) 400 (204) 465 (240) Very Good Excellent Good Fair Good No Best used in dry conditions at high temperatures
Polyimide(PI/P84) 465 (240) 500 (260) Good Fair Good Good  Fair No Non-flammable and thermostable organic fiber
PTFE (Telfon) 500 (260) 536 (280) Fair Good Excellent Excellent Excellent No Expensive-excellent chemical and thermal resistance
Fiberglass (GL) 500 (260) 536 (280) Excellent Fair Excellent Fair Fair No Finishes limited, maximum temperature range.  

- This table serves only as a guide for the selection of engineering materials and filter media
- Testing in accordance with the end user’s safety guidelines is recommended
- P84, PTFE, and Fiberglass: sentitive bag to cage fit for good energy performance

1.2 Fabric Construction

Nonwoven: The felt constrfuction is scrim supported or self-supported. Packing of scrim supported felts is a woven scrim. Self Supported needle felts , where the backing is a batt of the same fiber as the felt itself.

There are some distinct advantages to having a self-supported compared to one with a scrim:

• Since the scrim does not aid in the filtering process, not all of the weight of a scrim-supported felt contributes to filtering. In a scrimless needle felt, all fibers, including the backing, are available for filtration.

• Fiber-supported needle felts are stronger than those with scrims, since stitching weakens scrims, but strengthens fibers.

• Fiber-supported needle felts are usually less expensive, since scrims typically cost more to produce than the fiber backing.

• Scrims can blind if dust completely penetrates the fiber mat.

• Fiber-supported needle felts flex better than those with scrims, providing for better pulse cleaning.

Woven: Woven fabrics are not as efficient as felted fabrics. Fiberglass is most commonly used as a woven, rather than felted fabric, but this material is fragile.

1.3 Fabric finishes

Fabric- Finishes/Surface Treatments Features & Benefits
Mechanical Finishes
Plain  Natural finish. General purpose material
Heat Set Passing media over a heated blanket.  Surface remaining intact, without fiber melting or burning.  Provides dimensional stability, resist changing shape, and eliminates shrinkage
Singed (one side or both sides) Exposing media to open flame to burn off any loose fibers.  Benefits: improved abrasion resistance, reduced fiber shedding, and in some cases improves the filtration performance.  Singeing the surface of felt reduces fiber ends protruding from the surface
Glazed/Eggshell (one side or both sides) Running the felt over heated rollers, which melts fibers and results in a smooth "eggshell" finish, which will enhance cake release  (may impede airflow) .   With the pressure between the rolls will adjust the permeability as well as impart stability to the fabric.  
Chemical Treatments
PTFE Impregnation (Bath/Penetrating)
Applied to high temperature filtration fabrics by full impregnation of fabrics in PTFE dispersion.
Imparts high level of oil and water repellency. Improves fabric cleanability and lowers operation pressure drop. Improves abrasion resistance. Prevents moisture and acids formed during dew point transitions from being absorbed by the filtration fabric.  Limited cake release
PTFE Membrane Increases collection efficiency and cake discharge. Protects the filter against chemical attack. Improves blinding resistance and bag life. Membrane provides an extremely smooth, high efficiency finish and the greatest cake release. For capture of fine particulate, improved filtration efficiency, cake release and airflow capacity
Flame Retardant Retards combustibility (not flame-proof)Reduces flammability of fabrics.
Slows spread of fire in situations when a flammable dust is ignited inside the dust collector system.
Water & Oil Repellent
( Hydrophobic & Oleophobic)
Provides a durable, clear protective barrier, characterized by extremely low surface tension; which improves cake discharge and enhances water and oil repellency. Main purpose is to prevent filter bags from binding caused by the accumulation of wet, sticky or agglomerating dust.
Anti-static filter media (use when static dissipation is required):  Improves conductivity of fibers.
Stainless steel scrim supported felt A woven scrim comprised partially of stainless steel yarns. 
Stainless steel fiber blend felt Use of stainless steel fibers blended with standard fibers. 
Epitropic fiber blend felt A blend of standard and epitropic (carbonized) fibers.  

> Other special finishes (Silicone, Acid Resistant, Flame Retardant, PTFE/Acrylic Coatings...) are customized on request
> Applicable media: Fiberglass with limited finishes. For more, please contact us

Benefits:PTFE Membrane

Near zero emissions meet or exceed the strictest regulatory standards while providing greater product collection

Excellent dust release characteristics

Increased bag life

Less frequent cleaning required

Reduced pressure drop results in energy savings

Lower maintenance costs lead to increased profitability

2) Selecting a Filter Bag

You should choose the media from which your filter bags will be constructed based on the type of application they will be used for and fabric selection guide provided.

Accurate measurements for your filters before ordering replacement filter bags are necceassry for the performance of the filter bags.

Bag reconfiguration includes:

- Overall Length

- Flat Width or Circumference

- Top and bottom construction of a filter bag involves a variety of possible configurations. The type of cleaning process used by the dust collector determines which configurations will be used in the design of the filter bag.

Please contact us for further information