Filter bags are used in dust collection systems to trap particulate matter that is released into the air during industrial processes. These filter bags can last anywhere from a few weeks up to 5 years or more, but there are several environmental factors that come into play when calculating the life expectancy of filters. While there are top factors that can influence filter life, it is important to understand why filter bags may fail prematurely. In this article, we will discuss the top reasons why filter bags fail and how to avoid them.
When calculating the life expectancy of filters, there are multiple environmental factors that play a role in the final answer, such as the volume of dust loading, air-to-cloth ratio, filter fit, installation, and dust characteristics. Dust characteristics and choosing the correct filter media for filter bags are one of the primary factors that can cause filter bag failure.
Dust Characteristics and Suitable Filter Media:
Dust is a heterogeneous mixture of particles, and it comes in different shapes, sizes, and chemical compositions. Moisture is one of the main contributors to filter bag failure. Standard dust collection systems are designed for dry dust environments. Therefore, if you have over 20% moisture or oils in your process, you may need to consider a different type of filtration system. Excessive moisture can cause dust to become sticky or heavy, which causes the dust cake to build quickly, affecting the ability of dust to fall off during cleaning and thereby creating a scenario where your filter bags fail prematurely.
Certain types of dust can also be abrasive, which can cause additional wear and tear to the filter bag. The hardness of the material being filtered and its shape are essential factors to consider when selecting a filter media for abrasive dust. Different types of filter media that are more resistant to abrasive dust include Aramid (Nomex), PTFE, Polyester, and Ryton. The velocity of your airflow can also make your dust more abrasive. Highly abrasive dust may require your housing to be fabricated in stainless steel, titanium, or other costly materials that can withstand long-term wear.
Filter Bag Fit and Installation:
Filter bag fit and installation also play a significant role in filter bag failure. Proper installation of filter bags allows for optimal dust handling and cleaning efficiency. Common errors to watch out for when it comes to filter bag installation include incorrect bag-to-cage fit, insufficient flex, and shrinkage due to high temperatures.
To help give your filter bags better life expectancy, it is crucial to have the proper bag to cage fit. Filter bags with the correct flex allow a precise amount of momentum to happen when the filters hit the cage. Filter bags with insufficient flex are too rigid and can prevent dust build-up from properly falling off during the cleaning process. The general recommendation is to have between 1/4″ to no more than 3/8″ pinch on your filter bag on each side of the cage. Fiberglass and PPS are filter bag media with a sensitive bag-to-cage fit. If you have filter bags with PTFE or P84 media, consider oversizing your filters due to shrinkage that can occur in temperatures above 450 Degrees F.
Filter bag design and installation
Filter bag design and installation is also critical factor in ensuring proper operation. Design flaws in filter bags can prevent the entire filtration system from operating correctly. During installation, it is important to ensure that the filter bags are not damaged, that the cages are the correct size and shape, and that the bags are not overloaded. A filter bag that is overloaded can cause it to stretch, which can damage the filter media, allowing dust to pass through.
In conclusion, filter bags are an integral part of the industrial filtration process, and their failure can lead to costly downtime, lost production, and increased maintenance expenses. By understanding the top three reasons for filter bag failure, dust characteristics, filter bag fit and installation, and taking steps to prevent these issues, you can ensure that your filter bags last longer, reducing costs and improving productivity.