--- title: "Bag Filter Housing: Types, Sizing & Selection Guide" date: 2026-08-07T00:55:25Z modified: 2026-08-21T00:55:48Z permalink: "https://www.hyflowtech.com/blog/basic/bag-filter-housing-selection/" type: post status: publish excerpt: "" wpid: 2172 categories: - basic featured_image: "https://www.hyflowtech.com/wp-content/uploads/2026/08/image-66.webp" featured_image_alt: Bag Filter Housing Types, Sizing & Selection Guide timestamp: 2026-08-21T00:55:48Z tags: - basic --- ## Quick Answer： A bag filter housing removes pollutants from pressurized liquids using standards like 3-A or ASME. Sizing relies on flow rates from 5 to 4,200 GPM and micron ratings down to 1 micron. HEYI [sanitary fittings](https://www.hyflowtech.com/wp-content/uploads/wp-mfa-exports/post/304-vs-316l-stainless-steel-for-sanitary-fittings.md) match these strict criteria by using polished stainless steel and crevice-free Tri-Clamp connections. Our ISO-certified approach is key to bypass-free seals for over 18,000 global industrial customers. ## What Is a Bag Filter Housing? This vessel is a pressurized container designed to hold filter bags. It removes sediment and particles from liquids under pressure. The housing contains a perforated basket that supports the filter bag. A hold-down plate secures the bag inside the vessel. When unfiltered liquid enters the vessel, it flows through the bag and exits cleaned. This design prevents particle bypass and ensures clean fluid recovery. B2B buyers may choose this solution for chemical, food, and pharmaceutical plants. ## How Do Bag Filters Work? Bag filters work by passing pressurized liquid from the inside of a filter bag to the outside. The filtration process follows these steps: - Liquid enters the inlet at the top or side of the housing. - The fluid flows from the inside of the filter bag to the outside. - Solids and contaminants are trapped inside the bag. - Clean filtrate passes through the support basket to the outlet. Because particles collect inside the bag, disposal is clean and simple. You do not have to clean the vessel walls during routine maintenance. ## Which Types of Housings Are Available? The three main types of housings available are single bag, multi-bag, and duplex bag filter configurations. Choosing the right vessel configuration depends on flow rate and downtime limits. ### Single Bag Housings A single bag housing holds one filter bag in a single chamber. These vessels are ideal for flow rates up to 180 gallons per minute (GPM). They have a small footprint and the lowest initial cost. However, you must stop the fluid flow to change the bag. This bag type may fit your needs if your facility has batch processing or operations with brief shutdowns. You can commonly find single vessels used in parts washing. They can also be present in small coolant loops and batch chemical processing. Standard bag sizes include: - Size #1 bags (7 inches by 17 inches) for flows up to 100 GPM. - Size #2 bags (7 inches by 32 inches) for flows up to 180 GPM. - Size #4 bags (4 inches by 15 inches) for flows up to 50 GPM. ### Multi-Bag Housings Multi-bag housings arrange 2 to 24+ bags in parallel inside one large vessel. They are designed for flow rates from 200 GPM to over 1,000 GPM. By dividing the flow, each bag loads more slowly. This extends the service interval from weekly to monthly changes. It reduces plant maintenance costs and labor needs. Changing multiple bags at once requires shutting down the vessel. It takes 15 to 30 minutes to swap all bags. ### Duplex Bag Housings Duplex systems have two separate chambers with a central transfer valve. While one chamber filters fluid, the other stands by with a clean bag. How it works is that when the active bag clogs, you turn the transfer valve. The flow immediately routes to the standby chamber. This allows you to change the spent bag with zero process interruption. ![The Core Mechanism: Inside-Out Filtration](https://www.hyflowtech.com/wp-content/uploads/2026/08/image-67-1200x670.webp)## Should You Choose a Bag or Cartridge Filter? You should choose a bag filter for high flow rates and a cartridge filter for sub-micron particle removal. Industrial filtration systems often require a bag filter vs cartridge filter comparison. The choice depends on particle size, flow rate, and operating environment. Here is a comparison table to guide your selection: | **Selection Criteria** | **Bag Filter Housing** | **Cartridge Filter** | | --- | --- | --- | | Particle Size | Medium to large particles (>2 microns) | Fine and ultra-fine dust (<1 micron) | | Typical Flow Rate | Medium to very high (up to 4,200 GPM) | Lower flow rates per housing | | Lifespan | Long (6 months to 2 years) | Shorter in high-dirt environments | | Initial Cost | Lower capital investment | Higher initial cost | | Applications | Heavy industrial, water treatment, chemicals | Pharmaceutical, food processing, electronics | ## SS304 vs SS316L: What Should You Choose? Select SS304 for general non-corrosive liquids, and select SS316L for aggressive chemical or high-purity sanitary applications. Stainless steel is the standard material for housing fabrication. Choose the right alloy for your liquid. ### SS304 Properties SS304 is the standard alloy for general industrial fluids. For water filtration and light chemicals, it also works well. This material offers excellent structural strength and durability. ### SS316L Properties SS316L contains molybdenum for superior chemical resistance. The “L” denotes low carbon, which prevents carbide precipitation during welding. SS316L resists pitting from chlorides, acids, and aggressive alkalis. It is the widely used material for pharmaceutical, food and beverage, and marine applications. ## How Do You Correctly Size a Housing System? Size a housing by matching your flow rate, liquid viscosity, and target micron rating to the vessel design. Proper sizing prevents high pressure drops and bag failure. You must balance initial cost with operating costs. ### Sizing Parameters To size a vessel, consider these parameters: - Maximum Flow Rate: Match the system GPM to the vessel capacity. - Liquid Viscosity: Viscous liquids like syrups or resins require larger housings to lower pressure. - Operating Temperature and Pressure: Standard housings are rated up to 150 PSI. - Micron Rating: Standard needlefelt bags filter from 1 to 200 microns. Woven mesh filters up to 1,200 microns. ### Pressure Limits and Maintenance Some providers suggest replacing filter bags at a differential pressure of 1.5 bar (21.7 PSI). The maximum limit is around 3.5 bar (50.7 PSI) to prevent bag bursting. ## Sanitary Design & CIP Sanitary filtration has strict hygiene requirements to protect human health. A sanitary stainless steel bag filter must prevent bacterial growth. ### Surface Finish and Connections All contact surfaces inside a sanitary vessel must be polished. The surface finish should have a roughness of Ra <= 0.3 or 0.4 microns. The housing must be free from pits, crevices, and sharp corners. Threaded connections are not allowed. Instead, the vessel must use Tri-Clamp or flange connections. This ensures no contaminants are trapped. ### CIP Cleaning Protocols Clean-In-Place (CIP) designs allow chemical cleaning without dismantling. CIP systems use spray devices to wash internal surfaces. This is critical for dairy, beverage, and pharmaceutical facilities. The design must meet 3-A Sanitary Standards. [ ![Sanitary Bag-Type Filter](https://hyflowtech.b-cdn.net/wp-content/uploads/2026/05/Sanitary-bag-strainer-filter.jpg) **Sanitary Bag-Type Filter** The Sanitary Bag Filter Housing is a high-capacity filtration vessel designed to hold a standard filter bag element for removal of particles. View Product ](https://www.hyflowtech.com/product/sanitary-bag-type-filter/) ## HEYI’s B2B Sanitary Solutions [HEYI](https://www.hyflowtech.com/wp-content/uploads/wp-mfa-exports/page/home.md) is a manufacturer of sanitary pipeline components, including premium filters and strainers. We provide integrated manufacturing from raw stainless steel to finished products. Explore our [sanitary filters and strainers](https://www.hyflowtech.com/wp-content/uploads/wp-mfa-exports/taxonomy/product_cat/filters-strainers.md) to upgrade your factory processing. You can also view our [Tri-Clamp connections](https://www.hyflowtech.com/product/heavy-duty-tri-clamp/) for leak-free sanitary pipe layouts. Contact HEYI today for professional engineering support and sanitary fitting inquiries. ## FAQ ### How often should I change a filter bag? Change the bag when the differential pressure reaches 1.5 bar (21.7 PSI). You should also swap bags during product changeovers to prevent batch cross-contamination. ### What is the maximum pressure for standard housings? Most standard industrial vessels are rated for 100 to 150 PSI. High-pressure applications require ASME code-stamped vessels. ### Can I clean and reuse filter bags? Needlefelt and meltblown bags are disposable. Reusing them damages the pore structure and causes particle bypass. Woven metal mesh bags can be cleaned. [ Contact US ](https://www.hyflowtech.com/wp-content/uploads/wp-mfa-exports/page/contact-us.md)