Choosing the Right Filter Bag Material
A baghouse collects dust and gases from production processes and turns the dirty air into clean gas. The dirt accumulates on the surface of the filter bags media, while the clean air passes through.
The bag filter media selection is key to successful baghouse performance. The most common fabrics are needle punched non-wovens that act as depth filters. Felt filter bags have high dirt holding capacity, broad chemical compatibility and oil absorbing capabilities.
Types
Choosing the right filter bag material is critical to the efficiency and life of the filter. The choice depends on a variety of factors, including abrasion resistance, temperature tolerance, chemical resistance and moisture resistance.
The most common type of filter bags are made from polyester. This material is excellent for abrasion resistance and has good chemical resistance, particularly to mineral acids and weak alkalis. It also has good dimensional stability, which reduces caking on the surface of the filter and helps to prolong its life. However, polyester is not suitable for use in moist environments or with highly corrosive chemicals.
Other types of filter bags are made from synthetic materials such as aramid, fiberglass and PTFE. These are best suited for applications with low to moderate abrasion and good chemical resistance. PTFE is highly resistant to moisture and most chemical agents, with the exception of high concentrations of nitric acid.
Other designs include molded top and ring-top filter bags. Molded top bags are made with polypropylene or polyester and have a molded lifting handle. They are available in standard industry sizing and can fit most manufacturers’ housings. These are sonically welded, which improves filtration quality and eliminates leaks and bypass that can occur with sewn seams. Ring-top bags have metal rings, typically galvanized steel, that are sewn to the top of the filter.
Materials
A wide range of materials are filter bag used to make filter bags. Selection is based on a number of factors, including maximum operating temperature, abrasion resistance, reaction to moisture, and chemical compatibility. Bags with higher tensile strength can support greater replacement pressure differences and are more resistant to deformation.
Woven mono and multi-filament fabrics, needlefelts, and meltblown nonwovens are typical filter fabric choices. Woven fabrics have excellent abrasion resistance but are sensitive to chemical environments and high temperatures. Needlefelts and meltblown nonwovens are more durable but have lower abrasion resistance than woven fabrics.
The pore volume of the material affects how quickly contaminants are trapped. Bags with a larger pore volume are more difficult to clean and have a shorter lifespan. For this reason, it is important to select a high-quality, low-cost filter bag material.
Pharmaceutical manufacturing requires stringent standards of purity and safety for the drugs they produce. Filter bags play a critical role in this process, which involves multiple filtration steps to remove impurities. The industry is also concerned with reducing air pollution caused by industrial processes and vehicular emissions. These particles are known as PM2.5, and they cause respiratory diseases and premature deaths. The use of filters helps reduce PM2.5 levels in the air by capturing them and preventing them from entering the human body.
Applications
In a variety of industrial applications, filter bags separate solid particles from liquid ingredients. For example, they are used in the oil and gas industry to remove impurities from drilling mud or fracking Drainage geonet fluids. They are also utilized in pharmaceutical production to ensure the purity of sterile drugs and liquid oral suspensions. Additionally, they are commonly used in the manufacturing of paints and coatings to ensure that contaminants don’t spoil finished products.
When choosing the right type of filter bag, several factors must be taken into consideration to ensure that it matches up with the specific needs of an application. These include material and micron ratings, as well as temperature and pressure resistance. The particle size rating of a bag is important because it determines how small a particle can be retained in the filtered substance. Using the correct size ensures that the contaminants are removed from the system without compromising process efficiency or product quality.
In addition, a bag’s maximum operating temperature is another factor to consider. In some cases, higher temperatures are required for certain applications. For these situations, it is important to select a high-temperature bag that will handle the operating conditions. A few examples of common high-temperature filter materials include nylon, polypropylene, and porous PTFE film. Ryton, a long-chain synthetic polysulfide developed by Phillips Petroleum, is another popular choice.
Maintenance
Bags can be used for longer than expected when they are properly maintained and monitored. Changing filters, monitoring differential pressure and cleaning the filter housing are all important to extend their life and keep them functioning properly.
When it’s time to change out filter bags, make sure the system is shut down and isolated to prevent contamination or spillage during removal. After the old bags have been removed, they should be disposed of according to local regulations and industry standards. Next, clean the filter housing to ensure a good seal and proper alignment. Finally, install the new filter bags and follow manufacturer guidelines to ensure a good fit and alignment.
The frequency of filter bag changeouts will vary depending on the types of contaminants and operating conditions. Regular inspections will help to assess the condition of the existing filter bags and determine whether they can be cleaned or if they need to be replaced. In some cases, the frequency of changeouts can be reduced by using high-quality filter bags that offer superior filtration performance.
Other maintenance tasks include regularly checking the temperature and pressure inside the filter housing and lubricating all moveable parts. Inspecting the O-rings to make sure they are in good shape is also crucial to ensuring a good seal and protecting against leaks. Finally, regular training of personnel on how to perform these maintenance and inspection tasks can help to minimize downtime and ensure optimal filtration system performance.