A Complete Guide to Common Air Filter Media

1. Nonwoven fabric (polypropylene fiber)

Features: A fluffy, porous structure; low cost at approximately RMB 5-10 per square meter; and light weight at 30-50 grams per square meter. Its disadvantages are low dust-holding capacity and poor moisture resistance.

Filtration efficiency: G3-G4, capturing at least 50% of particles larger than 5 micrometers.

Applications: Coarse filtration in household air conditioners, prefiltration for shopping-mall ventilation and dust screens for printers.

2. Nylon mesh (woven polyamide)

Features: Washable and reusable, strong and corrosion resistant, but with low filtration precision, capturing only particles larger than 10 micrometers.

Applications: Range-hood filters, dust protection for industrial fans and prefiltration for laboratory fume hoods.

3. Metal mesh (woven aluminum or steel)

Features: Withstands temperatures up to 200 degrees Celsius, resists impact and offers a service life of 5-10 years, but costs about five times as much as nonwoven media.

Applications: Boiler-room ventilation, automotive engine air intakes and prefiltration for kitchen-oil-fume purifiers.

Medium-efficiency filter media

1. Glass fiber

Features: Entangled ultrafine fibers provide F5-F8 efficiency, capturing 40%-90% of particles from 1 to 5 micrometers, with a high dust-holding capacity of 3-5 kilograms per square meter. The fibers may shed, however.

Applications: Hospital operating rooms, prefiltration for electronics cleanrooms and commercial central air-conditioning systems.

2. Polyester fiber (PET)

Features: Electrostatically charged media that can be washed 5-10 times, with low airflow resistance and good resistance to microorganisms. It is suitable for humid environments.

Applications: Hotel fresh-air systems, food-plant workshops and the medium-efficiency stage of household air purifiers.

3. Activated-carbon fiber

Features: Spun coconut-shell activated carbon with a formaldehyde adsorption capacity of at least 150 milligrams per gram. It must be combined with another filter medium because it does not provide effective dust filtration on its own.

Applications: Odor removal in new vehicles, bathroom exhaust systems and formaldehyde control in office buildings.

High-efficiency filter media

1. HEPA (High Efficiency Particulate Air)

Types:

Traditional: Borosilicate glass fiber, providing at least 99.97% efficiency for 0.3-micrometer particles at H13 class.

Composite: Glass fiber plus electrostatically charged polypropylene, providing H14 efficiency of at least 99.995%.

Disadvantages: High resistance of 150-300 Pa, not washable, and a typical price of approximately RMB 500-1,000 for one H13 filter.

Applications: Hospital intensive-care units, semiconductor workshops and biosafety cabinets.

2. ULPA (Ultra Low Penetration Air)

Features: At least 99.9995% efficiency for 0.12-micrometer particles at U15 class. It costs three to five times as much as HEPA media and requires rigorous sealing.

Applications: Chip-photolithography workshops, aerospace clean compartments and nuclear-industry laboratories.

Specialty media for specific applications

Antimicrobial filter media

Core composition: Silver ions or nano titanium dioxide.

Special function: At least 99% inhibition of microbial growth.

Typical applications: Hospital pediatric departments and veterinary hospitals.

High-temperature filter media

Core composition: Ceramic fiber and silica sol.

Special function: Withstands temperatures up to 500 degrees Celsius.

Typical applications: Industrial kilns and automotive exhaust purification.

Biodegradable filter media

Core composition: Polylactic acid (PLA).

Special function: Naturally degrades within six months.

Typical applications: Environmentally focused shopping malls and temporary ventilation at exhibitions.

Electrostatically charged filter media

Core composition: Polypropylene with an electrostatic treatment.

Special function: Reduces resistance by 30% and increases efficiency by 20%.

Typical applications: Household air purifiers and air-conditioning systems in new-energy vehicles.

Practical selection and maintenance guidance

1. Selection tips

Ordinary environments: Use nonwoven coarse media plus polyester medium-efficiency media.

Demanding environments: Use glass-fiber medium-efficiency media plus HEPA media.

2. Maintenance intervals

Clean coarse filters every 1-3 months, replace medium-efficiency filters every 3-6 months, and replace high-efficiency filters every 1-2 years according to the differential-pressure alarm.

Activated-carbon media fails when wet. Wear a dust mask when replacing glass-fiber media.

From shopping-mall ventilation to chip-manufacturing workshops, filters made from different materials form a precise air-protection system through variations in structure and composition. When selecting a filter, compare the material options against the contamination level, ambient humidity and budget of the application to achieve the best balance between filtration efficiency and cost.