What Kind of Material is Glass Fiber in the Filter Cartridge?

In modern filtration systems, glass fiber Filter Cartridges have become an extremely common and preferred choice. They are widely used in industrial water treatment, food and beverage production, electronics, medical, and laboratory fields. But what exactly is this material, and what makes it special? Let's take a closer look.

1. Differences Between Glass Fiber and Polypropylene (PP)

Polypropylene (PP) is another commonly used filter material. While both serve as filtration media, they differ significantly: Glass fiber structure offers excellent high-temperature resistance and chemical corrosion resistance, allowing stable operation at higher temperatures. PP, as a plastic material, generally has a lower temperature tolerance but offers good flexibility and hydrophilicity at normal temperatures. Glass fiber can achieve high-precision filtration through different fiber diameters and arrangements, with stable structure. PP often forms a gradient density through melt-blown or string wound processes, making it suitable for general particulate filtration. Glass fiber is more suitable for harsh environments such as high temperatures and strong acid/alkali conditions, while PP is cost-effective for ordinary water treatment and air filtration.

2. How Is Glass Fiber Used in Filter Cartridges?

(1) As a Filtration Media

The core form of glass fiber as a filtration media is the String Wound Filter Cartridge. Its production relies on high-precision CNC winding equipment, which wraps glass fiber yarn of specific thickness layer by layer onto a porous inner liner tube (usually made of polypropylene or stainless steel), with preset tension and cross angles.

This process creates a progressive gradient filtration structure - from outside to inside, with pore sizes decreasing gradually - enabling true "depth filtration." Impurities are not only trapped on the surface but are also adsorbed step by step along the depth of the filter layer. This allows the cartridge to maintain high filtration accuracy while offering much greater dirt-holding capacity and service life than surface filters. 

For example, Hongtek's GSW Series Glass Fiber String Wound Filter Cartridges feature a glass fiber filtration media combined with a stainless steel inner skeleton, allowing them to withstand temperatures up to an impressive 400°C. Coupled with the inherent acid and alkali resistance of glass fiber, they are the preferred choice for industrial fluid filtration scenarios that demand high reliability and durability, such as chemical and petrochemical industries, electroplating and surface treatment, and electronics and semiconductor sectors.

Additionally, glass fiber can be flexibly used in small pleated filter cartridges (OD 2.5") to meet applications with limited space and high flow requirements. Utilizing a unique pleating process, it achieves a much larger effective filtration area within a compact size compared to traditional designs. This allows the cartridge to provide higher fluid throughput under the same pressure drop or maintain a lower initial pressure drop at the same flow rate, thereby extending the replacement cycle.

As seen in Hongtek's OPF Series Oilfield Pleated Filter Cartridges, we can supply small pleated cartridges with glass fiber as the filtration media. The pleated design expands the filtration area, resulting in very low pressure drop and superior flow characteristics compared to depth media of micron-rated filters. Oilfield pleated filters offer high dirt-holding capacity, long service life, and stable filtration efficiency, making them widely used in critical industrial fields such as oilfields, power plant circulating water treatment, petroleum industry, solvents, selected acids/alkalis, and chemical processing.

Their shared advantages include:

● Wide range of filtration accuracy: By adjusting fiber thickness and winding techniques, different precision needs from coarse to fine filtration can be met, providing flexibility in selection.

● Deep filtration with high dirt-holding capacity: The gradient structure allows contaminants to be stored within the filter layer rather than merely clogging the surface, resulting in a longer service life.

● High-temperature and corrosion resistance with strong adaptability: The glass fiber itself can withstand relatively high temperatures (typically above 80°C, and higher with special treatment) and a wide range of acid-base chemical media, offering excellent stability.

(2) Used for External Skeletons or End Caps - Reinforced with PP Blend

Beyond serving as filter media, glass fiber is also commonly used for structural reinforcement. For instance, in the manufacturing of external skeletons or end caps for some high-flow cartridges, PP blended with glass fiber is used to form high-strength support structures through injection molding. This thickened skeleton, reinforced with glass fiber, significantly enhances the cartridge's pressure resistance and overall durability, preventing deformation or damage under high-pressure or high-flow conditions. This is particularly suitable for large-scale industrial filtration systems. For example, Hongtek's HFM Series Pleated High Flow Cartridge Filters feature an external skeleton that is not only an extremely pressure-resistant single-piece structure but also a single-piece skeleton reinforced with glass fiber blend. Such a design is widely applicable across most fields and is one of the preferred products in many water treatment industries.

3. Conclusion

In summary, glass fiber is an exceptional material for both filtration and reinforcement. It can serve as a high-precision filtration layer resistant to harsh environments, as well as a structural material to enhance the overall strength and stability of filter cartridges. When selecting a Filter Cartridge, if high temperature, corrosion resistance, or high-precision filtration is required, glass fiber cartridges are often the more reliable choice. In scenarios demanding both structural pressure resistance and high flow capacity, cartridges designed with a combination of glass fiber and PP demonstrate unique comprehensive advantages. Understanding the characteristics of materials is key to better matching the most suitable filter cartridge for a system.