In the automotive painting process, the HEPA Filter with Separator is a key air purification component. It is mainly used in the supply and exhaust air systems of the spray booth (paint booth). Its core function is to control particulate matter in the air, which directly affects painting quality, coating performance, and compliance of the production environment. Its specific effects can be seen in three areas: process guarantee, quality improvement, and environmental control.

Automobile painting has extremely high requirements for air cleanliness (especially for the intermediate coating and topcoat processes, which need to reach ISO 8-7 cleanliness levels). If tiny dust particles (≥0.3μm) in the air adhere to the surface of the workpiece or the paint, it will cause defects such as “particles”, “pinholes”, and “shrinkage cavities” in the coating. The core value of the partitioned high-efficiency filter lies in its efficient retention of particulate matter, which is specifically manifested as:
Filtration efficiency meets the standard
The filter meets HEPA (High Efficiency Particulate Air) standards. It achieves a filtration efficiency of at least 99.97% for particles ≥0.3μm. It effectively removes dust, fibers, and metal debris from the supply air. This ensures the air entering the spray booth is clean and free of unwanted particles.
Air flow uniformity guarantee
The partitioned high-efficiency filter is usually equipped with a “V-shaped” or “flat plate” structure. Inside, aluminum foil/paper partitions are used to separate the filter material channels. This not only prevents the filter material from deforming and ensures the ventilation area, but also guides the airflow to pass through the filter material evenly, avoiding the “turbulence” caused by excessively high local airflow velocity – turbulence may stir up the accumulated dust in the spray booth. Secondary contamination of the workpiece surface.
Stable load-bearing capacity
Compared with the high-efficiency filter without separators, the structure with separators has a stronger pressure-bearing capacity (capable of withstanding a wind pressure of 150-300Pa), making it suitable for the “high air volume and high air pressure” supply air requirements of spray booths (typically the supply air volume of spray booths is 200-400m³/h · ㎡). During long-term use, it is less likely to experience a decline in filtration efficiency due to wind pressure fluctuations, ensuring process stability.
Ii. Key Values: Enhance coating quality and reduce rework rate
The “appearance texture” (such as gloss and smoothness) and “durability” (such as corrosion resistance and adhesion) of automotive coatings are core indicators. The separator high-efficiency filter indirectly improves the quality of the coating by controlling pollution.
Reduce coating defects
If there are particles in the air, “particle points” (which need to be manually ground and repaired) or “pinholes” (holes left when particles fall off after the paint dries) will form after spraying. In severe cases, rework and re-spraying are required. The filter can reduce such defect rates by over 90%, especially for the “mirror surface paint” of high-end cars (such as metallic paint and pearlescent paint), it can prevent particles from affecting light reflection and ensure the “mirror effect” of the coating.
Ensure the adhesion of the coating
If dust adheres to the surface of the workpiece, it will hinder the adhesion of the paint to the substrate (such as the body steel plate, electrophoretic layer), resulting in insufficient adhesion of the coating (prone to peeling and cracking in the later stage). The filter purifies the supply air, reduces the dust deposition on the surface of the workpiece, and indirectly enhances the bonding strength between the coating and the substrate, meeting the testing standards for coating adhesion in the automotive industry (such as the grid method and the circle method).
Iii. Environmental and Compliance Effects: Control the spread of VOCs, meeting environmental protection and occupational health requirements
The paints used in automotive spraying (such as solvent-based topcoats) will release VOCs (volatile organic compounds), and “paint mist” (suspended paint particles) will be produced during the spraying process. The high-efficiency filter with separators can assist in controlling the diffusion of pollutants in the exhaust system
Intercept paint mist and reduce the load of VOCs treatment
In the exhaust system, the partition high-efficiency filter is usually used as a “pretreatment unit”, first intercepting the unadhered paint mist particles (to prevent the paint mist from entering the subsequent VOCs treatment equipment, such as RTO incinerators and activated carbon adsorption towers), preventing the paint mist from blocking the channels of the VOCs treatment equipment, and improving the operational efficiency and service life of the subsequent environmental protection equipment.
Protect the health of operators
If the paint mist and dust are directly discharged into the workshop, long-term inhalation by the operators may cause respiratory diseases (such as pneumoconiosis and asthma). The filter can control the particulate matter concentration in the exhaust air at ≤0.5mg/m³ (in compliance with the “Emission Standard of Air Pollutants for Automobile Manufacturing Industry” GB 27632-2011), reducing occupational health risks.
Reduce pollution to the external environment
The exhaust air processed by the filter has a significant reduction in particulate matter emissions, avoiding air pollution around the factory area. This helps enterprises meet the emission compliance requirements of environmental protection departments and reduces the risk of environmental penalties.
Iv. Comparison with Non-Partitioned High-Efficiency Filters: Why Are Partitioned Types More Favored in Automotive Painting?
In the automotive painting scenario, although the separator high-efficiency filter is slightly more expensive, it has more advantages than the non-separator type (separated by hot melt adhesive). The specific differences are as follows:

Comparison dimension	High-efficiency filter with partition (aluminum foil/paper partition)	High-efficiency filter without separator (hot melt adhesive)
Wind pressure resistance capacity	High (150-300Pa), suitable for large air volume supply	Low (≤120Pa), prone to deformation due to wind pressure
Temperature resistance	Good (can withstand 60-80℃, suitable for the room-temperature thermal environment of spraying)	Poor quality (≤50℃, high temperature is prone to cause the adhesive layer to fail)
Service life	Long (usually 6 to 12 months, depending on the working conditions)	Short (3-6 months, the adhesive layer is prone to dust accumulation and blockage)
Maintenance cost	Low (Low replacement frequency, reduced downtime)	High (Frequent replacement, affecting production efficiency)