What is the grade of sintered glass filter used for bacterial filtration?

What is the grade of sintered glass filter used for bacterial filtration?

Understanding the correct grade of sintered glass filter for bacterial filtration is critical for professionals in the sintered metal filters industry. Selecting the proper filter grade ensures effective removal of bacteria, preventing contamination in sensitive processes. This article highlights industry standards, particle retention ratings, and key selection considerations for sintered glass filters in sterile filtration.

Sintered Glass Filter Grades for Bacterial Filtration

- Common Grades:

- Grades G1 to G5 per ISO 4793 and other standards.

- Bacterial filtration typically uses finer grades (G3, G4, G5).

- Effective Pore Size:

- G5 grade: approx. 1.0–1.6 µm pores; captures most bacteria (>0.8 µm).

- G4 grade: approx. 1.6–2.5 µm; also used if smaller particles are not a concern.

- Reference Data:

- US Pharmacopeia and European Pharmacopeia both specify filters retaining particles ≥0.45 µm for sterilizing bacteria ((https://www.usp.org/)).

Why Grade G5 is Typical for Bacterial Filtration

- Key Benefits:

- Retains Bacillus subtilis, E. coli, and most common bacteria.

- Provides an optimal balance between flow rate and retention efficiency.

- Used in laboratories, pharmaceuticals, and analytical applications.

- Limitations:

- Viruses and smaller particles (<0.2 µm) may not be completely retained; higher performance (membrane) filters may be required for absolute sterility.

Specifying Sintered Glass Filters: Key Considerations

- Filtration Goal: Ensure bacterial removal rather than just particulate capture.

- Material Compatibility: Sintered glass is suitable for non-reactive, non-corrosive processes.

- Thermal/Mechanical Strength: Sintered metal filters (stainless steel, bronze) can be used when higher durability is necessary.

- Certification Standards: Confirm compliance with recognized standards (e.g., ISO 4793, ASTM E128).

Alternatives: Sintered Metal Filters

- Sintered stainless steel filters offer robust performance for higher temperatures, aggressive chemicals, and back-flush cleaning.

- Pore sizes down to 0.2 µm are available, providing finer bacterial retention compared to standard glass grades.

Authoritative Sources

- ISO 4793: Laboratory filter classification.

- USP <1231>: Water for pharmaceutical purposes.

- Merck Millipore: Filtration guidelines and product specifications.

In summary:

Grade G5 sintered glass filters (1.0–1.6 µm pore size) are widely accepted for bacterial filtration in professional laboratories and industry. For stricter sterility, consider ultrafine sintered metal filters or dedicated membrane filters depending on your process requirements.

For more information on advanced sintered metal filter solutions, contact our team—your trusted partner in precision filtration technology.