Cellulose filters are much cheaper than glassfiber filter cartridges. But are they really cost-effective over the long term?
The difference in manufacturing cellulose filters and glassfiber filters
To create cellulose fibers, long chains of plant material (mainly wood pulp and cotton) are processed into a pulp and then pulled out into strands. The irregular diameters of the cellulose fibers result in poor porosity and variable pore sizes. It’s impossible to replicate and obtain a trustworthy micron rating with random sized holes. Moreover, cellulose fibers become less effective when temperatures rise. Filters made of cellulose are more susceptible to structural modification and deterioration. The random size of the pores makes it impossible to duplicate and obtain a trustworthy micron rating other than a nominal rating.
With the production of fiberglass, thin glass rods are used to make a porous, homogenous filter material. A more challenging procedure in which molten silica fibers are wound into strands and connected with a resin binder. In comparison to cellulose fibers, inorganic glass media fibers have smaller, more consistent diameters. Since there are more glass fibers per volume due to their smaller diameter, there are more areas for them to trap and hold dirt, which results in a higher dirt holding capacity. Glass filter elements are rated for absolute efficiency and are regarded as a superior substitute for cellulose due to their efficiency and reliability.
Cellulose and Glassfiber cartridges, nominal or absolute rating?
Understanding how various media types affect the performance of a filter is essential when selecting the best filter solution. Nominal and absolute efficiency ratings are used to rate filters. Nominal ratings describe filtration levels based on the mass of solid particles. However, filters with a nominal efficiency rating do not have a maximum pore size, which means that they may still permit undesirable bigger particles to pass through and perhaps harm some system components. Media with absolute ratings have pores of a consistent size and are valued based on the biggest particle size that can pass through.
Cellulose (paper) filter material is unreliable and inconsistent. Due to the random size of the pores, it’s impossible to duplicate and obtain a reliable micron rating other than a nominal value. Filters rated < 10 micron are not feasible. Large-diameter fibers also have fewer pores, which has a negative impact on their ability to trap dirt and causes the initial pressure drop to be higher. Nominal rated means they might be only 50% effective.
The uniformity of the pores ranging from 0.5 – 50 micron of a glass fiber element creates a consistent filter media that can be reliably duplicated; therefore, a β-ratio of 5000 is repeatable and achievable. They are 99,98% efficient and are therefore absolute rated.
So before selecting a filter element, check the Beta ratio. Despite having the same micron rating, components of various media might have very varying filtration efficiency.
Lifetime of a cellulose filter element versus a glassfiber filter element
Low pressure drop and low efficiency characterize cellulose constituents. All other variables being equal, glass elements have a high efficiency and a higher pressure drop. As you’d expect, filter efficiency and pressure drop go hand in hand. Additionally, higher performance usually comes with a higher price. Glass is more expensive to purchase than cellulose components. But what matters is the lifetime of a filter element. The amount of money spent per gram or ounce of dirt that is caught and retained is what counts. Therefore, glass filter elements can last three to five times longer than cellulose-based alternatives.
This means that if you ever conduct a thorough cost comparison, don’t forget to include the cost of replacing the elements into account. You can avoid changing filters by using a glass element that lasts three times as long. You can save four filter changes if it lasts five times as long.
It might be expensive to use the incorrect type of filters in the appropriate locations. We can help you selecting the right type of filter.