Improving indoor air quality is a critical concern for both residential and commercial environments. Air filters play a fundamental role in controlling airborne contaminants, ensuring healthier air, and protecting HVAC systems.
This article provides a detailed and technically accurate overview of different types of air filters, their efficiency ratings, selection criteria, and maintenance best practices.
What Are Air Filters and Why Are They Important?
Air filters are mechanical or electrostatic devices designed to remove particulate matter and, in some cases, gaseous pollutants from the air. They are essential components of heating, ventilation, and air conditioning (Hvac) systems, air purifiers, and specialized industrial equipment.
The primary function of an air filter is to trap airborne particles such as dust, pollen, esporos de mofo, bacteria, fumaça, and volatile organic compounds (Vocs). Removing these contaminants is vital not only for occupant health—reducing respiratory irritations, allergies, and exposure to pathogens—but also for maintaining the operational integrity of HVAC systems. Accumulated dust and debris can degrade system performance, increase energy consumption, and lead to costly repairs.
In environments with stringent air quality requirements, such as hospitals, laboratórios, and manufacturing cleanrooms, rail transportation, selecting the appropriate air filter is critical for compliance with health and safety standards.
Qual é a classificação MERV em filtros de ar?
O valor mínimo de relatório de eficiência (Merv) is an industry-standard rating system developed by ASHRAE that quantifies a filter’s effectiveness at capturing airborne particles of various sizes. MERV ratings range from 1 para 20, with higher numbers indicating higher filtration efficiency.
The following table summarizes the MERV rating ranges, the particle sizes they target, and typical applications:
| MERV Rating Range | Particle Size Range (Microns) | Example Particles | Filtration Efficiency and Typical Applications |
| 1-4 | 3.0 para 10 | Dust, pollen, Fibras de carpete | Basic filtration for large particles; common in residential window AC units |
| 5-8 | 1.0 para 3.0 | Legionella bacteria, dust mite debris | Suitable for standard residential and commercial buildings; captures smaller dust and mold spores |
| 9-12 | 0.3 para 1.0 | Smoke, aerosols, some viruses | High-efficiency filtration appropriate for hospitals and high-occupancy commercial spaces |
| 13-16 | 0.3 para 1.0 | Bactérias, fumaça | Used in healthcare facilities and laboratories; capable of filtering bacteria and smoke |
| 17-20 | 0.3 and smaller | Microscopic particles including many viruses | HEPA and ULPA filters used in specialized cleanrooms; highest level of filtration |
Also read: Qual é a classificação MERV em filtros de ar? Tudo que você precisa saber
De que classificação MERV eu preciso para casa?
Common Types of Air Filters and Their Key Features
Air filters generally fall into three main categories: mechanical, electrostatic, and activated carbon filters, each addressing different pollutants and applications. Here is an overview of the most common types:
1. Fiberglass Filters
Fiberglass filters are the most basic type. They use layered fiberglass fibers to trap larger dust particles. They are inexpensive and provide minimal resistance to airflow, but their filtration efficiency is low, usually corresponding to MERV ratings of 1 para 4. These filters are best for protecting HVAC systems but offer limited air quality improvement.
2. Filtros plissados
Pleated filters consist of folded fabric or paper material that increases the surface area for trapping particles. They generally have MERV ratings from 8 para 13. These filters capture a wider range of particle sizes, including mold spores and pet dander. Their denser material improves filtration without significantly reducing airflow, making them a popular choice for homes and offices.
3. Electrostatic Filters
Electrostatic filters use static electricity to attract and hold airborne particles. They can be either washable or disposable. Their MERV ratings vary widely, often between 8 and 13. While they can capture small particles effectively, their performance depends on the static charge, which may weaken over time or with washing.
4. Filtros Hepa
Ar de partícula de alta eficiência (Hepa) filters are designed to capture at least 99.97% of particles down to 0.3 microns. These are used in environments requiring very clean air, such as hospitals, laboratórios, and clean rooms. HEPA filters have very high filtration efficiency but also cause high airflow resistance. HVAC systems need to be specifically designed or upgraded to handle HEPA filters.
5. Filtros de carbono ativados
Activated carbon filters are primarily used to remove odors, gases, and volatile organic compounds (Vocs). They do this by adsorbing these substances onto the porous surface of activated carbon. These filters are often combined with other types like pleated or HEPA filters to provide both particle and gas filtration.
5. Filtros de carbono ativados
Paint booth filters are specially designed to capture overspray particles, dust, and contaminants during painting processes. This type of air filters typically made from fiberglass, polyester, or synthetic media. Also these filters can be divided into four types: intake filters, exhaust filters, air makeup filters, and specialty filters.
Read more: What Are Different Types of Paint Booth Filters?
| Air Filter Type | Material | Typical MERV Rating | Prós | Contras | Application |
| Fiberglass Filters | Layered fiberglass fibers | 1 – 4 | Low cost Minimal airflow resistance Protects HVAC components | Low filtration efficiency Not effective for small particles Frequent replacement | Basic HVAC protection, residential use |
| Filtros plissados | Folded fabric or paper | 8 – 13 | Better filtration than fiberglass Captures mold spores and pet dander Reasonable airflow | Higher cost than fiberglass Needs regular replacement Not for very fine particles | Homes, offices, edifícios comerciais |
| Electrostatic Filters | Electrically charged synthetic fibers | 8 – 13 | Washable and reusable Effective for small particle Moderate cost | Performance drops as static weakens Requires cleaning Filtration less consistent | Residential and light commercial use |
| Filtros Hepa | Dense mat of randomly arranged fibers | Acima 13 (not standard MERV) | Extremely high filtration efficiency Captures bacteria and viruses Ideal for sensitive environments | High airflow resistance Expensive Requires specialized HVAC systems | Hospitais, labs, clean rooms, critical environments |
| Filtros de carbono ativados | Porous activated carbon | N/A | Removes odors and chemical pollutants Can combine with particle filters | Does not remove particulate matter Limited lifespan Frequent replacement needed | Odor control in homes, industrial air purification |
| Filtros de cabine de tinta | Fiberglass, polyester, synthetic media | Varies; often not rated by MERV | Effectively traps paint overspray and contaminants Maintains clean painting environment Multiple design options | Frequent replacement needed Can increase airflow resistance if clogged Higher cost than standard filters | Automotive paint booths, industrial spray painting, furniture manufacturing |
How to Choose Between Different Types of Air Filter?
Selecting the right air filter requires balancing several factors: filtration efficiency, airflow resistance, custo, and application environment.
- Understand Your Needs: For example, a standard office might only need a pleated filter with a MERV 8 para 11 rating. In contrast, medical or industrial spaces might require HEPA filtration.
- Consider HVAC Compatibility: Not all HVAC systems can handle filters with high MERV ratings. A filter too dense can reduce airflow, leading to higher energy costs and system wear.
- Evaluate Indoor Air Quality Concerns: If odors or VOCs are a problem, activated carbon filters are beneficial. For allergy sufferers, filters that capture smaller particles (Merv 11 and above) are better.
- Budget and Maintenance: Fiberglass filters are cheap but need frequent replacement. Pleated and electrostatic filters offer better value over time. Filtros Hepa, while expensive, provide unmatched air cleanliness but have higher maintenance and installation costs.
Tips for Maintaining and Replacing Your Air Filter Effectively
Proper maintenance is crucial for maximizing your air filter’s effectiveness and lifespan.
- Check Filters Regularly: Inspect your filter every month, especially during high usage seasons like summer and winter.
- Replace on Schedule: Follow manufacturer recommendations, typically every 3 months for pleated filters. Electrostatic washable filters should be cleaned regularly according to instructions.
- Keep Spare Filters: Having replacements on hand prevents system downtime and ensures consistent air quality.
- Maintain HVAC System: A clean HVAC system reduces dust buildup and improves filter performance. Regular professional servicing is advisable.
- Monitor Air Quality: Using air quality monitors can help you determine when filters need replacement or upgrade.
At Filtro arejado, a dedicated air filter manufacturer, we recommend evaluating your specific environment and air quality goals before selecting a air filter type. If you require guidance or customized filtration solutions, our technical experts are available to assist with product selection and application support. No further than us today!
