How Does a Filter Bag Work?

Filter bags are a widely adopted and highly effective method of liquid filtration, offering a practical solution for a broad spectrum of industrial processes. At Cleanova Allied, we specialise in manufacturing premium quality filter bags and housings tailored to meet the stringent demands of industries where consistent, high-performance filtration is critical.

The Filtration Principle

A filter bag functions by physically removing particulate matter from liquids through mechanisms known as depth or surface filtration depending on the construction of the media. During operation, unfiltered liquid enters the inlet of a bag filter housing and is evenly distributed across the interior surface of the bag. Filtration occurs from the inside to the outside of the filter bag.

As the liquid passes through the media, suspended solids, including dirt, debris, and other contaminants, are captured and retained within the filter bag. The clean, filtered liquid exits the housing through the outlet, ready for further processing or use.

Key Components of a Filter Bag System

  1. Filter Bag Media
    Allied manufactures filter bags using various materials to suit diverse process requirements. Common materials include needlefelt, melt blown (or microfibre), and monofilament mesh. Several polymer types are available, and each is selected for specific characteristics such as chemical compatibility, temperature resistance, and retention efficiency. The most common are polypropylene, polyester and nylon.
  2. Support Basket
    Each filter bag is seated within a stainless steel or polypropylene perforated support basket, which provides structural reinforcement. This basket supports the bag under pressure and ensure it maintains its form during filtration, even at high flow rates.
  3. Sealing Collar
    The filter bag is equipped with a moulded or stitched collar or ring, and is available in materials like polypropylene, polyester, or stainless steel, which ensures a positive seal with the housing. This prevents fluid bypass and maintains the integrity of the filtration process.
  4. Filter Housing
    The filter housing is designed to withstand process pressures and temperatures and maintain safe, leak free operation. Allied filter bag housings are available in stainless steel or polypropylene constructions and are suitable for various flow rates and process conditions.

Performance and Efficiency

As filtration progresses, contaminants accumulate inside the bag, creating a differential pressure between the inlet and outlet sides of the system. This pressure gradually increases until the filter bag reaches its recommended changeout differential pressure and dirt-holding capacity. At this point, the bag is easily removed and replaced or, in some applications, cleaned and reused.

 

Cleanova Allied’s filter bags are designed for:

  • High dirt-loading capacity
  • Long operational life
  • Low pressure drop
  • Consistent particle retention performance
  • Minimal maintenance downtime

Application Versatility

Filter bag systems are a highly versatile filtration method and are suitable for use in both batch and continuous processing. Their robust design and operational simplicity make them ideal for applications across a wide range of industries, including:

  • Water and wastewater treatment
  • Food and beverage production
  • Cosmetics manufacturing
  • Chemical , pharmaceutical and petrochemical processing
  • Automotive and metalworking
  • Paints, coatings, inks, and adhesives
  • Power generation and pulp & paper

Why Choose Cleanova Allied?

With over 40 years of experience in liquid filtration, Cleanova Allied is the UK’s leading manufacturer of filter bags, filter housings, and custom filtration solutions. Our filter bags are manufactured in-house under stringent quality controls to ensure consistency, reliability, and optimal performance in critical applications.

We offer:

  • A comprehensive range of micron ratings and media types
  • Custom fabrication and private labelling options
  • Expert technical support and application guidance
  • ISO 9001-certified quality management systems
  • Rapid lead times and UK-based manufacturing
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