A single-bag filter housing retains a single woven or felted filter bag (Size 1: 180×810 mm, Size 2: 180×415 mm) inside a pressure vessel — liquid enters the bag from inside, particles are retained by the bag fabric, and clarified filtrate exits through the housing outer shell. Processing 1–100 m³/h per housing at particle ratings of 1–1,500 µm and pressures up to 10 bar, it provides the lowest-cost, simplest liquid-solid separation for batch and continuous applications — the first-choice filter for general industrial, food, and chemical clarification when solids loading is below 500 mg/L.
Liquid enters the bag from the inside (top-in, inside-out flow) or outside-in depending on design — standard Size 1/Size 2 top-entry bags receive liquid inside the bag and particles accumulate on the inner bag surface. As the bag loads with solids, inlet pressure rises until the differential pressure limit (0.5–2 bar) is reached — at which point the dirty bag is removed, discarded or cleaned, and replaced. Bag change takes 2–5 minutes. Multi-ring support basket inside the housing provides structural support to prevent bag collapse under maximum pressure differential.
Challenges
Frequent Bag Replacement at High Solids Loading (>100 mg/L)
At high TSS, bags fill within hours — high bag consumable cost and labour interruption frequency.
Bag Bypass at Bottom Seal Due to Particle Weight or Bag Slump
Particle weight causes bag bottom to slump below the seal ring — unfiltered liquid bypasses bag at bottom seal.
Bag Integrity Failure (Pinhole or Seam Rupture) Contaminating Filtrate
Bag failure passes all upstream particles directly to filtrate — no downstream particle detection.
Incompatibility of Standard PP Bag with Solvent-Based Process Fluid
Standard polypropylene or polyester bag swells, dissolves, or loses strength in organic solvents.
High Bag Consumable Cost on High-Flow Applications
Large-volume applications generate very high bag replacement frequency — running cost exceeds capital cost quickly.
Solutions
- Pre-Filtration Strainer (200 µm) to Remove Coarse Load Before Bag: Strainer removes coarse fraction — extends bag life 3–5× by reducing total load on fine-rated bag.
- Weighted Bottom Ring on Bag + Bayonet-Lock Basket: Weighted ring keeps bag open at bottom; bayonet basket locks bag — prevents slump and bypass.
- Downstream Turbidimeter (Online, 0–100 NTU Alarm): Turbidity alarm detects bag failure immediately — initiates bypass to spare housing before contamination reaches process.
- PTFE Bag (Chemically Inert, Compatible with All Organic Solvents): PTFE fabric rated for all solvents, acids, and alkalis — zero swelling or strength loss.
- Multi-Bag Housing (3B) for High-Flow Applications: Multi-bag housing multiplies capacity — reduces bag change frequency proportionally.
Applications
- Chemical: Process fluid clarification, catalyst recovery, pigment slurry pre-filtration.
- Food & Beverage: Beverage clarification, cooking oil polishing, syrup and wine clarification.
- Pharmaceutical: WFI pre-filtration, raw material particle removal, API process fluid clarification.
- Industrial: Coolant clarification, paint pre-filtration, electroplating bath clarification.
- Water Treatment: Well water pre-filtration, process water polishing, stormwater pre-treatment.
Models & Capacities
Type 3A — Single-Bag Filter Housing: Models & Capacities | ||||||||||
Model | Scale | Bag Size | Flow Rate [m³/h] | Filter Rating [µm] | Max Pressure [bar] | Max Temp [°C] | Inlet/Outlet Ø [mm] | Bag Material Options | Housing Material | Weight [kg] |
BF-1-S | Lab | Size 2 | 1–35 | 1–1,500 | 10 | 120 | DN 40 / DN 40 | PP, Nylon, PE, PTFE | SS 316L / CS | 12 |
BF-1-M | Lab/Pilot | Size 1 | 1–55 | 1–1,500 | 10 | 120 | DN 50 / DN 50 | PP, Nylon, PE, PTFE | SS 316L / CS | 18 |
BF-1-HP | Pilot | Size 1 | 1–55 | 1–1,500 | 16 | 150 | DN 50 / DN 50 | PP, Nylon, PE, PTFE | SS 316L | 28 |
BF-1-HYG | Pharma/Food | Size 1 | 1–40 | 1–500 | 10 | 140 | DN 40 TC | PP, Nylon, PTFE | SS 316L Ra<0.8 | 32 |