How to Choose Filter Media for a Primary-Efficiency Filter

I. Select for Dust Concentration and Particle Size

1. Dust Concentration

High-dust environments, such as industrial workshops and outdoor-air intakes:

Give priority to polyester, or PET, nonwoven fabric or nylon mesh. These materials have a dense surface-fiber structure and high dust-holding capacity, withstand heavy particle loading, and resist wear. A polyester filter, for example, may have a relatively low initial resistance of approximately 20-50 Pa while providing a dust-holding capacity of 500-800 g/m², making it suitable for long-term, high-load service.

Low-dust environments, such as offices and residential air conditioners:

Polypropylene, or PP, nonwoven fabric is a suitable choice. It is lightweight, soft, inexpensive to replace, and has a low resistance of approximately 10-30 Pa. PP media is often used as the prefilter in a household air purifier, where it captures particles larger than 5 μm and provides a dust-holding capacity of approximately 300-500 g/m².

2. Particle-Size Distribution

Predominantly large particles, such as wood chips, pollen, and coarse dust:

Choose wire mesh, including galvanized-steel or aluminum mesh, or coarse-fiber polyester fabric. With openings of 50-100 μm, these materials are less prone to clogging and are suitable for removing large contaminants during pretreatment. Wire-mesh filters can be washed and reused, making them appropriate where maintenance costs must be controlled.

Predominantly small and medium particles, such as smoke and fine dust:

Electrostatically charged electret nonwoven media, made from materials such as PP or PET, is recommended. Electrostatic attraction captures particles of 2-10 μm, producing higher efficiency than ordinary nonwoven fabric, including G3 or G4 primary-efficiency performance, while resistance rises more slowly.

II. Select for Temperature and Corrosion Resistance

1. Temperature Range

Normal-temperature environments, no higher than 80°C:

Most PP and PET nonwovens and nylon meshes are suitable, economical, and easy to replace.

High-temperature environments, 80-250°C:

Use glass-fiber filter paper or wire mesh such as stainless-steel mesh. Glass-fiber media can withstand temperatures up to 250°C and is often used to prefilter high-temperature industrial flue gas. However, it has relatively high resistance of approximately 80-120 Pa and cannot be washed.

Low-temperature environments, such as cold-storage facilities:

Choose low-temperature-resistant nylon mesh. It remains flexible at -30°C and is less likely to become brittle or break.

2. Corrosion Resistance

Ordinary environments:

Polyester fiber or PP nonwoven fabric is sufficient. No special surface coating is required, keeping costs low.

High-humidity, acidic, or alkaline environments, such as laboratories and chemical workshops:

Choose stainless-steel mesh or a polytetrafluoroethylene, or PTFE, coated screen. Stainless steel offers strong rust resistance, while a PTFE coating resists acid and alkali corrosion and suits air containing chemical gases such as SO₂ and HCl.

III. Select for Cost and Ease of Maintenance

1. Disposable Versus Washable Filters

Disposable filters, such as PP or PET nonwoven fabric

Advantage: The price is low, approximately RMB 5-20 per panel, replacement is convenient, and no cleaning is required.

Application: In low-pollution settings such as homes and offices, replacement every three to six months is recommended.

Washable filters, such as wire mesh and nylon mesh

Advantage: They have a long service life, can be reused five to ten times, and provide a lower long-term cost.

2. Balancing Cost and Efficiency

For a low initial cost, choose PP nonwoven media. It suits budget-limited applications with frequent replacement, including commercial air-conditioning systems.

For long-term economy, invest in wire mesh or electrostatic electret media. Although initial cost is higher, including approximately RMB 50-100 per panel for stainless-steel mesh, less frequent replacement makes it suitable for industrial equipment in continuous service.

For homes and offices, PP nonwoven media is the preferred economical and lightweight option, while an electrostatic electret treatment can improve filtration efficiency.

For industrial or heavily polluted environments, choose polyester fiber or wire mesh for durability and impact resistance, then evaluate long-term cost against the required cleaning frequency.

For special environments involving heat or corrosion, always select a material with the corresponding environmental resistance so filter failure does not damage equipment.

Considering these three dimensions together helps a primary-efficiency filter achieve the best balance of filtration performance and cost in its intended application.