Bag Filter Housing
Bag Filter Housing System
Bag filter housings function as robust pressure vessels engineered to hold replaceable filter bags for reliable solids removal from liquids. Fluid enters the housing, flows through the bag (trapping particles inside the media or on its surface), and exits as clean filtrate. These housings provide an economical and practical solution whenever moderate solids loading, rapid maintenance, and straightforward operation remain important. Industries frequently rely on bag filter housings for applications in chemicals, paints & coatings, food & beverage, water treatment, pharmaceuticals, and various process streams.
System Design & Key Components
Designers create bag filter housings as single-bag or multi-bag pressure vessels equipped with a perforated stainless steel support basket. This basket supports and stabilizes the filter bag during operation. Operators insert the bag and secure it at the top using a snap-band, O-ring, or flange ring before closing the lid. Liquid generally enters above the bag, passes downward through the media, and leaves through a bottom or side outlet. Housings are available in stainless steel, carbon steel, or high-grade plastic with quick-access closures such as V-clamps, swing bolts, or eye-bolt mechanisms.
Filtration & Maintenance Process
Users typically follow this sequence to operate and maintain the system:
- Initial Preparation — Clean the housing, insert a fresh filter bag, close the lid securely, and vent any trapped air.
- Normal Filtration — Pump liquid into the housing under pressure (usually 2–10 bar); solids collect inside the bag while filtrate exits.
- Performance Monitoring — Observe differential pressure. When it reaches 1–2 bar — or visual inspection reveals heavy loading — stop the flow to prepare for replacement.
- Bag Change-Out — Depressurize, open the lid, remove the used bag (using the handle or ring), dispose of it or clean if reusable, and install a new bag.
- Restart — Secure the lid, vent air, and resume operation. The entire replacement usually takes only 5–15 minutes.
Bag Filter Housing vs. Cartridge Housing Comparison
| Feature | Bag Filter Housing | Cartridge Filter Housing |
|---|---|---|
| Filtration Mechanism | Depth filtration (solids captured inside bag) | Surface or depth (pleated, wound, or melt-blown cartridges) |
| Solids Holding Capacity | High (large internal volume per bag) | Moderate to high (especially pleated types) |
| Change-Out Speed | Very fast (5–10 minutes) | Moderate (10–20 minutes for multi-cartridge) |
| Consumable Cost | Low (bags are inexpensive) | Higher (cartridges cost more) |
| Best Suited For | Moderate to high solids, coarse-to-medium filtration | Low solids, fine filtration, polishing |
| Typical Micron Range | 1–200 μm (nominal) | 0.2–100 μm |
Typical Operating Parameters
| Parameter | Typical Range | Notes |
|---|---|---|
| Micron Rating | 1–200 μm (nominal) | Depends on bag material and construction |
| Operating Pressure | 2–10 bar (30–150 psi) | Maximum recommended differential pressure usually 1.5–2.5 bar |
| Flow Rate per Bag | 5–50 m³/h | Varies by bag size (#1, #2, #3, etc.) |
| Standard Bag Sizes | #1 (7" × 16"), #2 (7" × 32"), #3–#5 | #2 size is the most widely used |
| Recommended Change-Out ΔP | 0.8–2 bar | Follow manufacturer guidelines |
Common Applications & Advantages
| Industry / Application | Typical Fluid | Primary Goal |
|---|---|---|
| Chemicals & Coatings | Resins, solvents, paints, inks | Particle removal, product clarity |
| Food & Beverage | Syrups, juices, edible oils, beverages | Clarification, solids control |
| Water Treatment | Process water, cooling water, rinse water | Equipment protection, fluid reuse |
| Pharmaceuticals | Intermediates, buffers, process liquids | Pre-filtration before finer stages |
| Industrial Processes | Cutting fluids, wash water, lubricants | Extend fluid life, reduce waste |
Key Advantages of Bag Filter Housings
- High solids-holding capacity extends service intervals
- Very fast bag replacement — typically no tools needed
- Low capital cost and economical consumables
- Broad range of bag materials and micron ratings available
- Compact housings integrate easily into existing systems
- Reliable performance for coarse-to-medium particle capture