How to Select and Procure Bag Filters

Bag Filter September 4, 2025 Multi Bag Filter Housing

1. Reasonable Selection of Filtration Precision for Bag Filter

Example: For electronic cleaning water, 1 μm is sufficient; for pharmaceutical liquids, 0.5 μm may be required; for general fine chemicals, 5–10 μm is more economical (to avoid excessive filtration that leads to short filter bag service life).
Higher precision is not always better; it must be determined according to actual needs.
Note: The “nominal precision” of a filter bag usually refers to either:
- Absolute precision (≥99% efficiency in capturing particles of that size or larger), or
- Nominal precision (lower retention efficiency).
  It is important to clarify the requirement.

2. Flow Capacity and System Pressure

High-precision filter bags have a lower dirt-holding capacity (pores are more easily blocked by impurities). Therefore, replacement frequency should be calculated based on impurity content, or a multi-bag structure (e.g., 2-bag, 4-bag in parallel) should be selected to increase throughput.
The system working pressure must be ≤ the design pressure of the filter (typically ≤0.6 MPa), to prevent bag rupture or housing leakage caused by excessive pressure.

3. Industry Compliance

For food and pharmaceutical industries: select food-grade / pharma-grade materials (e.g., 304/316L stainless steel housing, filter bags without fluorescent agents) and provide material certifications (e.g., FDA, USP Class VI).
For the electronics industry: select filter materials that minimize particle shedding or ion release (e.g., low metal-leaching stainless steel).