Pocket filters are the kinds of filters that are used in HVAC systems and applications to remove the particles of dust from prevalent or ambient air. They are usually applied as a final filter in different commercial applications or act like pre-filters for HEPA filters in varied size hospital settings and in the Pharmaceutical Industry. Pocket filters were historically produced from glass fiber media, however in recent years a shift to synthetic media took place. Glass fiber media is highly prone to bacterial growth and seasonal shedding. On the other hand, it has the advantage of enhanced filtration efficiency with the passage of time.
Synthetic media filters are generally electrostatically charged to amplify the efficiency. The drawback of the method is the media loses efficiency almost by 75% with time. To remedy this, developers have introduced novel kind of multilayer synthetic media with a smaller fiber diameter. Not just does this method contribute to a lesser loss of efficiency, but also to a service life that is longer by over 30%. Some filters arise with bacteriostatically treated media to avoid bacterial growth, while others are fitted with the media that is intrinsically not very suitable for the bacterial growth.
Pocket filters usually made with a pocket number ranging from 3 to12, which is based on the frame size. Frame material is of usually metal or plastic. The most general or widely used frame sizes (in mm) include 592 x 592, 592 x 490, 592 x 287 and 287 x 287. In spite of the in the synthetic media, commercial air pocket filters are gradually being overtaken by hard type filters made from glass fiber paper or from nanofiber. These filters generally give a service life of around 4-8 times that is given by pocket filters at a lower energy consumption.