G3/G4 bag filter is the core equipment for air pre-filtration in the coating industry, designed for intercepting overspray paint mist, dust, fiber and large particle pollutants generated during painting and spraying. It complies with EN 779 G3/G4 level (corresponding to MERV 8-11 or ISO Coarse 70%-90%), can efficiently capture particles above 5-10μm, protect the rear-end high-efficiency filter (such as paint mist felt, activated carbon) from clogging, reduce equipment maintenance costs, and improve coating quality and environmental compliance.
Core structure and technical characteristics
Material and process
Filter material: oil-resistant polyester fiber (PET) non-woven fabric, hydrophobic and anti-static treatment to prevent paint mist adhesion and fiber clumping; some models add flame retardant coating to reduce fire risks.
Bag design: 6-12 V-shaped pleated filter bags, the filtration area increases 3-5 times after unfolding, the dust holding capacity is 400-800g/m², suitable for high dust load environment.
Frame: galvanized steel or rust-proof aluminum frame, resistant to solvent corrosion, edge EPDM sealing strip to ensure no side leakage.
Performance parameters
Filtration efficiency:
G3 level: interception rate of 5μm particles ≥70% (EN 779 standard);
G4 level: interception rate of 5μm particles ≥90%, PM10 filtration efficiency ≥80% (ISO 16890 ePM10).
Initial pressure difference: ≤50Pa (@ rated air volume), reducing fan energy consumption by 10%-20%.
Environmental resistance: temperature resistance -20℃ to 80℃, humidity ≤90%, and resistance to volatile gases of paint thinners (such as xylene, acetone).
Core advantages
Advantage dimensions Value of the coating industry
High-efficiency pre-filtration intercepts more than 80% of overspray paint mist and large particles, extends the life of paint mist felt and activated carbon filter element by more than 50%, and reduces consumables costs.
Oil-resistant and anti-stick Oleophobic coating prevents wet paint mist from adhering, reduces filter bag clogging, and extends maintenance cycle to 3-6 months.
Safe and flame-retardant Flame-retardant models (UL94 V-0) reduce the risk of fire in the paint spraying room and comply with OSHA and NFPA safety regulations.
Economic and environmentally friendly Washable design (dry paint mist only), supports water gun flushing or compressed air backwashing, reused 5-8 times, and reduces waste.
Typical application scenarios in the coating industry
Automobile spraying:
Pre-filtration on the ceiling of the body spraying room to intercept overspray particles of primer and varnish;
Repair the ventilation system of the workshop to protect the precision paint mixing equipment from dust pollution.
Industrial coating:
Engineering machinery, metal component spraying line, filtering metal dust and paint mist;
Wood furniture UV paint spraying, intercepting wood chips and paint residue.
Environmental management:
Combined with dry paint mist filter (such as labyrinth/carton type) to form a multi-stage purification system to improve VOCs treatment efficiency;
Pretreatment of spray paint exhaust gas to reduce the load of back-end activated carbon or RTO equipment.
Selection and maintenance guide
Selection key parameters
Paint mist type:
Water-based paint: select hydrophobic G4 filter bag (moisture-proof and mildew-resistant);
Solvent-based paint: select oil-resistant G4 filter bag + flame-retardant frame.
Air volume adaptation:
Calculate the air volume according to the volume of the spray paint room and the number of ventilation times (usually 20-60 times/hour), and select the number of filter bags (such as 10,000m³/h corresponds to 12-16 bags).
Maintenance optimization strategy
Pressure difference monitoring: Install a pressure difference gauge, and the recommended replacement threshold is 150-200Pa (2-3 times the initial value);
Cleaning method:
Dry paint mist: Compressed air backflush (pressure ≤ 0.4MPa) or vacuum cleaner cleaning;
Wet paint mist: Directly replace the filter bag (avoid cleaning and damage to the fiber structure).
Replacement cycle:
Medium spray load: 3-4 months;
High load continuous operation (such as automobile production line): 1-2 months.
Coating industry solution upgrade
Intelligent linkage system:
Pressure difference sensor links fan frequency conversion control, dynamically adjusts air volume, and saves 15%-30%;
RFID tags record filter element usage data to achieve digital operation and maintenance management.
Compound function design:
Optional front metal mesh intercepts sparks, or rear activated carbon layer absorbs VOCs to build an integrated purification chain.
G3/G4 bag filters have become the cornerstone of air treatment in the coating industry with **”efficient interception, oil resistance and durability, economic and environmental protection”**. From automotive spraying to industrial painting, it not only protects the quality of equipment and products, but also helps companies achieve the dual goals of green production and cost reduction and efficiency improvement with its recyclable design.
