Air Filter FAQ — Guangzhou LJF Air Filter Manufacturer

Guangzhou LJF is a professional air filter manufacturer covering the full filtration chain, from filter media to finished filters:
Spray booth ceiling filter media (600G top ceiling cotton) — uniform airflow and dust-free paint finish;
Paint stop / floor filter rolls (fiberglass paint arrestor media) — high-capacity overspray and paint mist capture;
HEPA filters (H13 mini-pleated and rigid types) — for cleanrooms, electronics, and pharmaceutical applications;
Pocket / bag filters (F5–F9) and panel & pleated pre-filters (G1–G4) — for HVAC and general ventilation;
Activated carbon filters and DPA series — for odor and VOC control in industrial exhaust;
All products are available in roll, sheet, and finished filter formats with full OEM/ODM support.

A professional spray booth normally uses a three-stage combination:
Ceiling filter (e.g. 600G top ceiling cotton): placed on the ceiling supply side to create uniform laminar airflow and prevent dust contamination on fresh paint surfaces;
Floor filter (fiberglass paint stop / paint arrestor filter): laid on the booth floor to capture overspray and paint mist drawn down by the exhaust;
Pre-filter at the air intake: protects the ceiling filter and extends its service life. Tell us your booth dimensions, airflow, and paint type — our engineers will recommend the exact grade, gram weight, and quantity.

Consider these factors: type of airborne contaminants, particle size and concentration, airflow rate and pressure drop budget, required efficiency class (G / F / H per EN 779 & ISO 16890, or MERV), regulatory requirements, and your maintenance budget.
Higher efficiency filters capture more particles but create more pressure drop and energy cost — the right balance depends on your system. Contact our filtration engineers with your system details and we will help you select the optimal solution.

Replacement frequency depends on the environment and operating load: pre-filters may need replacement every few weeks to months; spray booth ceiling cotton is typically judged by operating hours and overspray load; HEPA filters are usually replaced when pressure drop exceeds the rated limit or particle monitoring shows leakage.
As a general guideline for HVAC systems, replace filters every 3–6 months. The most reliable signal is monitoring pressure drop across the filter bank — we recommend installing a differential pressure gauge.

Our products are used in paint & spray booths, cleanrooms, electronics and semiconductor plants, LCD manufacturing, bio-pharmaceuticals, food processing, hospitals, rail transit, petrochemical, and commercial/residential HVAC systems.
With over 10 years of experience and 3,000+ customers in 30+ countries, we provide tailored solutions across these industries.

Yes. We produce filters and media in custom dimensions, shapes, and frame specifications to fit your exact equipment. High-precision cutting and forming lines handle everything from small replacement pads to large industrial filter banks.

Absolutely. We provide full OEM/ODM support: custom logo printing, private labeling, neutral packaging, and technical specification printing on media and finished filters. Many distributors build their own brand with our factory-direct manufacturing.

Yes. Spray booth ceiling cotton and floor filter media can be produced in a wide range of gram weights (e.g. 100G–650G+) and thicknesses (e.g. 5–100 mm) to achieve your target filtration efficiency, dust holding capacity, and pressure drop.

Yes. We can supply flame-retardant / self-extinguishing media for high-heat spray booths, high-temperature fiberglass media for paint baking ovens, and composite media (e.g. synthetic fiber laminated with activated carbon) for multi-functional filtration.

Yes. Our R&D team supports 1:1 sample replication — we analyze the sample, match dimensions, gram weight, materials, and performance, then produce a matching product. Send us your sample or drawing and we will quote accordingly.

Guangzhou LJF operates a strict quality management system, and our products can be produced and tested in line with international standards such as ISO 9001, EN 779, ISO 16890, and EN 1822. Third-party test reports and certificates (e.g. ISO, SGS, CE) are available on request.

Our H13 mini-pleated HEPA filters offer ≥99.95% efficiency at MPPS per EN 1822 (H14 available at ≥99.995%). HEPA filters are individually tested for integrity to ensure certified performance in cleanrooms, electronics, and pharmaceutical applications.

DHC is the amount of dust a filter can hold before it becomes saturated and needs replacement, usually expressed in grams per square meter of media. Higher DHC means longer service life, lower replacement frequency, and reduced total cost of ownership — a key advantage of our high-gram-weight ceiling and floor media.

We control quality from raw material to finished product: incoming material inspection, in-process checks on gram weight, thickness, and uniformity, and final inspection (efficiency, pressure drop, dimensions) before packing. Random sampling per batch ensures every shipment meets the agreed specification.

We offer flexible MOQs. Standard specifications support trial orders and small quantities, while ordering in full rolls (e.g. 2×20 m) or full containers maximizes shipping efficiency and lowers your unit cost. 【Please confirm: current MOQ policy for stock rolls.】

Standard items in stock can ship quickly; regular production orders are typically ready within 7–15 days, depending on quantity and specification. 【Please confirm: actual lead times for stock, standard, and custom orders.】

Yes. We keep buffer stock of fast-moving items (600G ceiling cotton, fiberglass floor filter rolls, pre-filter media) and can prioritize production for urgent maintenance or emergency replacement needs. Contact us to confirm current availability.

Yes. As a source factory we maintain substantial raw material and finished-goods inventory, supporting large bulk orders with fast dispatch. Stable supply and quick delivery are core advantages we offer B2B clients.

Simply contact us by email, phone, or WhatsApp with your requirements (product, size, quantity, destination). Our process: specification confirmation → quotation & sample → PI → production → inspection → shipment → after-sales support. We reply to inquiries within 24 hours.

We support FOB, CIF, CFR, EXW, DDU, and DDP. We can work with your forwarder or arrange door-to-door delivery ourselves, including customs clearance on DDP shipments.

For urgent needs, our factory is only 10 km from Guangzhou Baiyun Airport, enabling fast air freight to Germany and Europe. Sea freight to Hamburg/Rotterdam typically takes about 30–40 days depending on the sailing schedule.

Yes. We encourage mixed-container loading (LCL or FCL) — for example, ceiling cotton rolls, floor filter rolls, and HEPA filters can ship together to maximize logistics efficiency and save freight cost.

We provide the full export document set: Commercial Invoice, Packing List, Bill of Lading / Air Waybill, and Certificate of Origin (CO / Form E where applicable) to help you clear customs and qualify for reduced import tariffs.

Guangzhou LJF is located in Guangzhou, southern China, only 10 km from Guangzhou Baiyun Airport, and close to the major ports of Guangzhou and Shenzhen. This strategic location gives us flexible logistics — fast air freight for urgent orders and competitive sea freight for bulk containers.

Heating, Ventilation, and Air Conditioning — the systems that control temperature, humidity, and air quality in buildings.

High Efficiency Particulate Air — a filter grade that captures at least 99.95% (H13) / 99.995% (H14) of particles at MPPS, per EN 1822.

Ultra Low Penetration Air — filtration above HEPA level (U15–U17), used in semiconductor and precision manufacturing.

Minimum Efficiency Reporting Value (ASHRAE 52.2) — rates filter efficiency from 1 (coarse) to 20 (HEPA-level); higher is more efficient.

The current international standard that classifies filters by efficiency at PM1 and PM10 particle sizes, replacing the old EN 779 G/F classes.

The weight of dust a filter can hold before saturation, measured in g/m² of media. Higher DHC = longer life, lower maintenance cost.

A measure of how well a coarse filter captures large particles (typically >3 μm), expressed as a percentage.

The airflow resistance of a filter, usually measured in Pa. Filters with high pressure drop increase fan energy cost — the key trade-off with efficiency.

Indoor Air Quality — the quality of air inside buildings, influenced by particles, gases, humidity, and ventilation.

American Society of Heating, Refrigerating and Air-Conditioning Engineers — develops filter test standards (e.g. ASHRAE 52.2).