At the forefront of biopharmaceutical research and development, vaccine production, and life science research, laboratory animal facilities (animal rooms) are crucial support platforms. Environmental control here directly impacts the scientific validity of experimental data, animal welfare, and the health of operators. Unlike ordinary industrial cleanrooms, animal rooms face a unique and severe set of challenges. Therefore, the air filtration systems serving them must undergo a “special design,” from materials to structure, to create an “invisible shield” that resists both chemical corrosion and biocontamination.
Unique Challenges Faced by Animal Facilities
- 1. The Main Force of Chemical Corrosion—Ammonia: Urea in animal excrement decomposes under the action of microorganisms, producing ammonia. Ammonia is readily soluble in water, forming an alkaline environment, and is highly corrosive to most metals (especially aluminum and copper) and common coatings. This can lead to rust and perforation of the filter’s metal frame, aging and powdering of sealing materials, ultimately causing structural failure and leakage.
- 2.Physical Clogging and Allergens—Hair and Dander: The large amounts of hair and dander produced by animal metabolism are the main visible particulate matter. These particles are relatively large and lightweight, easily accumulating on the filter’s airflow side, forming a “hair felt.” This not only quickly clogs the filter media and increases air resistance, but is also a potent allergen itself.
- 3. Core Biosafety Threat—Microorganisms and Aerosols: Animal respiration, activity, and excrement generate bioaerosols carrying bacteria, viruses, and fungal spores. These microorganisms can colonize the surface of damp filter media or in the frame gaps, forming biofilms. This not only reduces filtration efficiency but can also become a potential source of cross-contamination and an amplifier for disease transmission.
How to Address HEPA /ULPA?
Line of Defense One: Strategic Choice of Corrosion-Resistant Materials
- Polymer Coating: Electrostatic spraying ofpolyvinylidene fluoride (PVDF) or epoxy resin-polyester hybrid powder coating onto the aluminum alloy frame surface. PVDF boasts excellent chemical resistance, weather resistance, and self-cleaning properties. The epoxy-polyester coating provides good adhesion and mechanical protection, making it suitable for most animal facility environments and the most cost-effective mainstream corrosion protection solution.
- All-plastic/composite frame: Utilizing a one-piece injection-molded frame of glass fiber reinforced polypropylene (PP) or polycarbonate (PC) . Completely eliminates metal corrosion, is lightweight, and offers excellent insulation. Suitable for harsh environments with high humidity, extremely high ammonia concentrations, or requiring frequent rinsing and disinfection.
- Special stainless steel: 316L stainless steel is used for key components or the entire frame. In humid ammonia environments containing chloride ions (from disinfectants), its pitting corrosion resistance is far superior to ordinary 304 stainless steel. However, it is more expensive and is typically used for localized critical seals or small, specialized equipment, rather than the entire large filter frame.
Second line of defense: Structural engineering to prevent clogging and biocontamination
1. Enhanced and innovative pre-filtration: Washable metal pre-filter: A stainless steel wire mesh with an appropriate mesh size is installed before the HEPA filter to intercept most hair and coarse dander. The filter media should be designed as easily disassembled, modular, and capable of being washed with a high-pressure water gun or immersed in disinfectant for frequent maintenance.
Automatic Roll-Up Pre-Filter: For large animal facilities, an automatic roll-up filter media can be used. Filter media sections clogged by hair automatically move to the roll, always providing a clean filtration surface and significantly extending the life of the downstream HEPA filter.
2. Bio-resistant Design of Filter Media and Surfaces:
Antimicrobial/Antiviral Filter Media: Inorganic antimicrobial agents (such as silver ions, zinc ions) are added during the filter media manufacturing stage, or the media undergoes an antimicrobial coating treatment. These additives interfere with the enzyme systems or cell membranes of microorganisms, inhibiting the colonization and reproduction of bacteria and fungi on the filter media fibers, preventing biofilm formation, and maintaining stable filtration performance.
Hydrophobic and Oleophobic Coating: The filter media undergoes a fluoride hydrophobic treatment. This makes the filter media surface less susceptible to wetting and adhesion by moist organic contaminants (such as protein-containing skin flake aerosols). Contaminants are more easily carried away by the airflow, reducing clogging and disrupting the moist adhesion environment favored by microorganisms.
Smooth and Sealed Structure: The interior of the filter frame should be smooth and free of dead corners to prevent particulate matter accumulation. All seams must be completely sealed to prevent unfiltered air carrying contaminants and microorganisms from leaking through. With increasing demands for animal welfare and laboratory animal ethics, and the promotion of the “3R” principle (Replacement, Refinement and Reduction), animal facility environmental control standards will become increasingly stringent. Trenntech maintains close communication with the Veterinary Resistance Research Center at the Free University of Berlin and has extensive experience in designing customized solutions for animal facilities, continuously safeguarding the microenvironmental stability of animal facilities on the path of life science exploration.