Other Dry Filtration Frequently Asked Questions


1. How do I know what filter media is best for my baghouse?
Media/finish is selected for specific application, operating conditions and specific particle containment characteristics. Various media have different air cleaning and air flow resistance efficiencies. Southern Filter Media (SFM) works with each OEM and end-user to determine the best filter media for your particular baghouse. There is no one-size-fits-all solution.

2. How can I extend the life of my filter bags?
There are many factors that contribute to shorter than desirable filter bag life. These include design and operating condition of the dust collector, type of dust, an improperly selected bag fabric, and many more factors. Just as there are many factors that contribute to shortening bag life, there are almost as many solutions to improving bag life. Since each process is unique, it is best to contact us. Our experts will be pleased to develop recommendations to improve your baghouse operation.

3. What is the PM 2.5 Standard for Air Quality?
The PM 2.5 standard measures airborne dust particles that are 2.5 microns in size or larger. PM 2.5 is often referred to as fine particulate matter and includes inhalable particles small enough to penetrate the thoracic region of the respiratory system. According to extensive research and data, smaller particles are the ones that pose the greatest health risks.

4. Want is Sonic Cleaning and how is this helpful for dust removal in my Reverse Air System?
For over 30 years, the use of sound (acoustic) vibrations produced by sonic horns, has been a well-accepted, effective practice for fluidizing unwanted dust and agglomerated particulate in industrial pollution control & process equipment. In reverse air baghouse cleaning systems, the cleaning action is gentler as compared to pulse jet systems. As a result, the dust will sometimes bridge in the bag and not drop to the hopper; the vibrating effect of the sound waves on the filter medium (bags) can prevent this from occurring.

5. Is a Sonic Horn useful for cleaning bags in a Shaker Baghouse?
Yes, shaker baghouse cleaning systems are gentler, as compared to pulse jet dust collectors. During cleaning, the dust will sometimes bridge in the bag and not drop to the hopper. The vibrating effect of the sound waves from the sonic horns on the bags can prevent this from occurring. In some instances, such as if the original shaker baghouse OEM is no longer in business or repair parts for the shaker cleaning assembly are no longer available, Southern Filter Media has been successful in tensioning the bags very tightly and using just the Sonic Horn to clean the bags. Contact us to learn more about whether sonic horns may be a useful adjunct to your baghouse operation.

6. What is the importance of Differential Pressure for my bag’s life?
Differential Pressure or pressure drop is the resistance of air flow; it may refer to the pressure differential across the entire system, across the entire baghouse, or just across the bags. For this question, we are referring to pressure drop across the bags. When new bags are installed the bags are open and the differential pressure is typically ~ .5”-1” water gauge. As the dust cake/filter cake builds, the differential pressure starts to climb. Depending on the design of the system, pressure should stabilize ~ 4”-7” water gauge. The higher the differential pressure, the more likely you are to blind/plug the bags or cause the dust to bleed thru. Contact us to discuss concerns in your baghouse and explore our range of solutions for measuring differential pressure.

7. Can I try bag samples to see how they work in my actual baghouse?
We are happy to provide samples for you to try for fit for initial evaluation in your baghouse. However, please recognize that since air goes the route of least resistance, if you install a couple of samples in a baghouse full of dirty bags, the majority of the air will rush to the clean bags until they become loaded with dust and they equalize in pressure with the rest of the bags in the house. For this reason, in order to get accurate test data, we typically recommend that you run a full baghouse of test bags. Contact us to learn more about trial evaluations.

8. What is PPS?
PPS or Polyphenylene sulfide is a polymer used for various high-performance baghouse filter media applications such as in coal-fired power plants. Contact our experts to see whether PPS is suited to your particular application and operating conditions including temperature, presence of corrosive chemicals, etc.

9. What is Denier?
Denier is a unit of measure for the linear mass density of yarns or filaments. It is defined as the mass in grams per 9000 meters of fiber.

10. What is Microdenier Fabric?
The term microdenier is used to describe filaments that weigh less than one gram per 9000 meters. Micro-denier fabric is either a homogeneous blend of standard denier and microdenier fibers or a standard denier base fabric with a micro-denier cap. This creates smaller air passages without affecting airflow, which in turn allows for smaller dust particles to be collected on the surface rather than penetrating into the depths of the felt. Southern Filter Media is pleased to work with you on evaluating whether microdenier fabrics are right for your application and operating conditions. Contact us to learn more.

11. What is ACFM and how is this measure used in various baghouse formulas such as calculating the Air-to-Cloth ratio?
ACFM is an Airflow Measure and stands for Actual Cubic Feet of Air Per Minute. It is utilized to calculate Air-to-Cloth Ratio, which is the volumetric flow rate of air flowing through a dust collector’s inlet duct divided by the total fabric area in the filters. Air-to-Cloth is expressed in units of velocity (ft/minute) and will depend on the dust loading. The Air-to-Cloth (A/C) ratio will be a function of many factors including type of dust collected, fabric type, and the bag’s cleaning mechanism, to name just a few factors. As a rule of thumb, reverse-air fabric filters have the lowest A/C ratios. Shaker systems typically have a higher A/C than shakers with pulse-jet baghouses having the highest A/C ratio.

Gross Air-to-Cloth Ratio = ACFM/Total Cloth Area (ft2)

Net Air-to-Cloth Ratio = ACFM/Total On-Line Cloth Area (ft2)

Contact SFM for assistance in optimizing cloth selection for your baghouse.