{"id":4473,"date":"2025-08-29T09:18:47","date_gmt":"2025-08-29T01:18:47","guid":{"rendered":"https:\/\/www.bacintl.com\/?p=4473"},"modified":"2025-08-29T09:18:47","modified_gmt":"2025-08-29T01:18:47","slug":"what-other-common-filters-are-there-in-the-automotive-painting-process","status":"publish","type":"post","link":"https:\/\/www.bacintl.com\/fr\/what-other-common-filters-are-there-in-the-automotive-painting-process\/","title":{"rendered":"Quels sont les autres filtres courants dans le processus de peinture automobile ?"},"content":{"rendered":"
In the automotive painting process, air purification is carried out in a “gradient” manner (from the fresh air in the workshop to the interior of the painting room and then to the exhaust air). Different links need to be matched with filters of different functions to achieve the hierarchical purification goal of “coarse filtration \u2192 medium filtration \u2192 fine filtration”, while dealing with special pollutants such as paint mist and VOCs. In addition to the previously mentioned partitioned high-efficiency filters, common filters also include the following six types, which are respectively applied in core links such as air supply, exhaust, and paint mist treatment. Their specific functions and application scenarios are as follows:<\/div>\n
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\nI. Pre-Filter: The “First Line of Defense” at the Fresh Air Inlet
\nThe primary filter is the first filtration unit for air entering the spraying system. Its main function is to intercept large particles of impurities in the air and protect the subsequent medium and high-efficiency filters (preventing large particles from clogging high-precision filter materials and extending their service life). It is the “key to cost control” in the purification of spraying air.
\nCore features and effects
\nFiltration accuracy: Mainly retains particles \u22655\u03bcm (such as dust, sand, leaves, insects, large fibers, etc.), and the filtration efficiency complies with G1-G4 grades (EN 779 standard), among which G3\/G4 grades (efficiency 50%-90%) are commonly used in automotive painting.
\nFilter material and structure: Low-cost filter materials such as non-woven fabric, glass fiber, and metal mesh are mostly used. The structure is mainly flat plate type and bag type (bag type filter material has a larger area and a higher dust holding capacity).
\nApplication scenarios: Installed at the fresh air intake of the spray painting workshop (such as roof fresh air valves, exterior wall air intake ducts), or as a pre-filter unit for air conditioning units.
\nCore value: Prevent large particles from directly entering the medium and high-efficiency filters, extend the replacement cycle of subsequent high-precision filters by 30% to 50%, and reduce the maintenance cost of the overall filtration system.
\nIi. Medium-Efficiency Air Filter: The core of hierarchical purification that “Bridges the upper and lower levels”
\nThe medium-efficiency filter is located between the primary and high-efficiency filters and belongs to the secondary filtration unit. Its function is to further retain the small and medium-sized particles not removed by the primary filter, reduce the “filtration load” of the high-efficiency filter, and ensure that the high-efficiency filter can focus on retaining fine particles (\u22650.3\u03bcm).
\nCore features and effects
\nFiltration accuracy: It can retain particles of \u22651-5\u03bcm (such as fine dust, pollen, and fiber debris), and the filtration efficiency complies with F5-F9 grade (EN 779 standard). In automotive painting, F7\/F8 grade (efficiency 80%-95%) is commonly used.
\nFilter material and structure: Superfine glass fiber and synthetic fiber (such as polyester fiber) are mostly used. The structure is mainly bag-type (with a large number of bags, a large filtration area, and a dust holding capacity 3 to 5 times higher than that of the primary filter). In some high-end scenarios, “V-shaped bag type” is used to further increase the air volume.
\nApplication scenario: Installed in the air conditioning supply duct (after the primary effect and before the high efficiency), or at the inlet end of the supply air static pressure box in the spray booth.
\nCore value: Without medium-efficiency filters, high-efficiency filters will be quickly clogged by particles of 1-5\u03bcm, and their lifespan may be shortened from 6-12 months to 2-3 months. Medium-efficiency filters can effectively avoid this problem and balance purification efficiency with cost.
\nIii. Paint Mist Filter: A “Specialized Equipment for Paint Mist Interception” in Exhaust Systems
\nDuring the car painting process, a large amount of paint mist (liquid paint particles not adhering to the car body, with diameters usually ranging from 1 to 10\u03bcm) is produced. If it directly enters the exhaust duct or environmental protection equipment, it will cause pipe blockage and failure of VOCs treatment equipment (such as the activated carbon adsorption tower being covered by paint mist and the nozzle of the RTO incinerator being clogged). The paint mist filter is a “directional filtration unit” specifically designed for paint mist and is a core component of the exhaust system.
\nCore features and effects
\nFiltering object: Mainly retains liquid paint mist particles, while also taking into account some solid dust. The filtering efficiency for paint mist can reach over 95% (preventing paint mist from entering subsequent equipment).
\nFilter material and structure
\nCommon type 1: Glass fiber paint mist felt (low cost, large dust holding capacity, suitable for solvent-based paints, capable of adsorbing solvents in paint mist);
\nCommon type 2: Polyester fiber paint mist cotton (stronger solvent resistance, suitable for water-based paint, can be repeatedly tapped to remove some paint mist, longer service life);
\nThe structure is mostly “folding type” or “winding type”, which increases the contact area with the paint mist and avoids the rapid accumulation of paint mist.
\nApplication scenario: Installed at the exhaust outlet end of the spray booth (before the high-efficiency filter or VOCs treatment equipment), it serves as the “pre-treatment unit” for exhaust purification.
\nCore value: Prevent paint mist from clogging subsequent equipment, extend the service life of VOCs treatment equipment (such as RTO, activated carbon), and at the same time reduce the corrosion of exhaust ducts by paint mist, lowering equipment maintenance costs.
\nIv. Activated Carbon Filter: The “Adsorption Expert” for VOCs and Odors
\nSolvent-based paints (such as varnishes and colored paints) used in automotive painting will release a large amount of VOCs (volatile organic compounds, such as benzene, toluene, and xylene) and pungent odors. Activated carbon filters utilize the “porous adsorption structure” of activated carbon to adsorb and treat VOCs and odors. It is a key device for “odor control” and “VOCs auxiliary purification” of spray exhaust air.
\nCore features and effects
\nFiltering target: Mainly adsorbs VOCs and odor molecules, and also has a certain retention capacity for some small molecule particles. The adsorption efficiency of VOCs is usually 60%-80% (depending on the type of activated carbon and air volume).
\nFilter material and structure: Granular activated carbon (coal-based, wood-based) or activated carbon fibers are adopted. The structure is mostly “honeycomb type” (with low air resistance and large adsorption area) or “bag type”. Some high-end models will add catalysts (such as potassium permanganate) to enhance the degradation efficiency of VOCs.
\nSc\u00e9narios d'application
\nAs the main VOCs treatment equipment for mid-to-low-end spraying lines (small workshops with low VOCs emissions);
\nAs a pre-treatment\/post-treatment unit for VOCs in high-end spraying lines (used in conjunction with RTO incinerators to adsorb unincinerated residual VOCs and further reduce emission concentrations).
\nCore value: Control the spread of odors in the spray painting workshop, reduce the concentration of VOCs emissions (to assist in meeting the GB 27632-2011 standard), and improve the air quality of the workshop and its surrounding environment.
\nV. HEPA Filter without Separator: A supplementary option for local high-precision purification
\nAlthough the “pleated high-efficiency filter” was previously mentioned as the mainstream in automotive painting, in local scenarios with small air volume and low air pressure, the pleated high-efficiency filter is also an important supplement. Its core advantages are “small size and low air resistance”, which is suitable for the purification needs of limited space.
\nCore features and effects
\nFiltration accuracy: Consistent with the partition type, the filtration efficiency for particles \u22650.3\u03bcm is \u226599.97% (HEPA standard), and some can reach ULPA level (\u22650.12\u03bcm, efficiency \u226599.999%).
\nFilter material and structure: Superfine glass fiber is used as the filter material, and hot melt adhesive is used instead of aluminum foil\/paper partitions to separate the filter material channels. The volume is 30%-50% smaller than that of the partition type with the same air volume, and the air resistance is lower (\u2264120Pa).
\nSc\u00e9narios d'application
\nLocal clean areas in the spray painting workshop (such as small parts spray painting stations and repair stations, with low air volume requirements);
\n“Top local air supply” in the spray booth (supplementing clean air to avoid local turbulence).
\nLimitations: Poor temperature resistance (\u226450\u2103), low wind pressure resistance capacity, not suitable for large air volume scenarios in the main supply air system, and shorter lifespan than the partition type (3-6 months).
\nVi. High-Temperature Resistant HEPA Filter: “Exclusive Purification” for the Drying Process
\nAfter the car is painted, it needs to enter a drying oven (such as intermediate coating drying and topcoat drying, with the temperature usually ranging from 80 to 180\u2103). During the drying process, residual solvents and a small amount of particulate matter will be volatilized. If these pollutants adhere to the surface of the workpiece, it will cause defects such as “orange peel” and “loss of gloss” in the coating. High-temperature resistant and high-efficiency filters are specifically designed for air purification in drying ovens and are suitable for high-temperature environments.
\nCore features and effects
\nFiltration accuracy: The filtration efficiency for particles \u22650.3\u03bcm is \u226599.97%, and it can withstand high temperatures ranging from 120 to 250\u2103 (divided into three grades of 150\u2103, 200\u2103, and 250\u2103 depending on the material).
\nFilter material and structure: High-temperature resistant glass fiber filter material is adopted, stainless steel partitions are used instead of aluminum foil\/paper partitions, high-temperature resistant silicone sealant is used (instead of ordinary rubber), and the shell is made of stainless steel (to prevent deformation at high temperatures).
\nApplication scenario: Installed at the air supply inlet end of the drying furnace to ensure the air entering the drying furnace is clean and prevent particles from adhering to the coating surface at high temperatures.
\nCore value: Solve the “high-temperature purification problem” in the drying process, ensure the appearance quality of the coating after drying (such as gloss and flatness), and prevent the filter from failing due to high temperature.
\nSummary of the “hierarchical application logic” of automotive spray filters
\nThe air purification for car painting is a “gradual” process. Different filters need to be combined and used according to “functional division”. A typical purification process is as follows:
\nFresh air inlet: Primary filter (G3\/G4) \u2192 Intercepts large particles;
\nAir conditioning unit: Medium-efficiency filter (F7\/F8) \u2192 Retains small and medium-sized particles, protecting high efficiency;
\nMain supply air of the spray booth: Partitioned high-efficiency filter (HEPA) \u2192 Fine filtration of fine particles to ensure cleanliness;
\nSpray booth exhaust: Paint mist filter \u2192 Paint mist interception \u2192 Activated carbon filter\/VOCs treatment equipment \u2192 VOCs adsorption \u2192 (optional) high-efficiency filter \u2192 final purification exhaust.
\nDrying furnace air supply: High-temperature resistant and high-efficiency filter \u2192 Fine filtration in high-temperature environment to ensure drying quality.
\nThis “graded purification” mode not only ensures the required cleanliness for spraying but also maximizes the lifespan of each filter, balancing purification effect and maintenance cost. It is an important guarantee for the stable operation of the automotive spraying process.<\/div>\n
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In the automotive painting process, air purification is carried out in a “gradient” manner (from the fresh air in the workshop to the interior of the painting room and then to the exhaust air). Different links need to be matched with filters of different functions to achieve the hierarchical purification goal of “coarse filtration \u2192 […]<\/p>","protected":false},"author":3,"featured_media":4474,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[92],"tags":[],"class_list":["post-4473","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry-technology"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/posts\/4473","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/comments?post=4473"}],"version-history":[{"count":2,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/posts\/4473\/revisions"}],"predecessor-version":[{"id":4476,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/posts\/4473\/revisions\/4476"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/media\/4474"}],"wp:attachment":[{"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/media?parent=4473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/categories?post=4473"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bacintl.com\/fr\/wp-json\/wp\/v2\/tags?post=4473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}