Bag filter and HEPA filter: How to choose?

If you know anything about filters, you may have heard of bag filters and HEPA filters. Although they are both devices used to filter turbid air, they have some key differences in function and performance.
First, let's take a look at bag filters. The working principle of this filter is simple. It uses a bag to capture solid particles in the exhaust gas. The bag is usually made of high-quality fiber material, and the pore size can be selected according to the required filtration level. When the exhaust gas passes through the bag, the solid particles are captured in the bag, while the relatively clean gas passes through. Bag filters are mostly used in filter exhaust boxes, filter boxes, and dust collectors.
In contrast, HEPA filters have a more complex structure and working principle. It uses a series of fine fibers and the force of electric charges to capture tiny particles. This filter is usually composed of multiple layers, each with different pore sizes and filtration efficiencies. HEPA filters are widely used in the medical, electronic, and biotechnology fields because they can quickly and efficiently capture microorganisms and other harmful particles, thereby protecting the safety of the environment and personnel.
Many people are wondering: Since they are all filtering air, why can't some purification equipment directly use HEPA filters? There are economic and workload factors involved. Take the negative pressure weighing room as an example. The return air holes at the bottom of the negative pressure weighing room are equipped with bag-type medium efficiency filters and primary efficiency filters, and the air supply area uses liquid tank high-efficiency filters. In some pharmaceutical dust weighing, some powder will inevitably fly out due to airflow, and most of this dust is visible to our naked eye, which means that its volume is relatively large. In workshop production, the amount of powder accumulated is very large. If a high-efficiency filter is used directly, the high-efficiency filter will be scrapped due to blockage in a short time, and because the filter material used for the high-efficiency filter cannot be cleaned and reused, this will not only double or several times the cost but also require a large number of replacements in a short time, resulting in a large waste of manpower and material resources.
In summary, the main difference between bag filters and high-efficiency filters lies in their structure and filtering principle. Bag filters are suitable for general particle filtration, while high-efficiency filters are more suitable for filtering tiny particles and microorganisms. Which filter to choose depends on your specific needs and application scenarios.