Prepainted Metal Sheets

We will describe the application of prepainted metal sheets in the ventilation duct in detail and illustrate it with examples.

1, Fabrication and connection of prepainted metal sheets air duct

·Fabrication: professional numerical control plasma cutting machine, plate shearing machine, seaming machine, bending machine and other equipment are used to cut, crimp and bite the prepainted metal sheets to make a section of rectangular air duct and the required elbow, tee, reducer and other parts.

·Connection of air duct with prepainted metal sheets :

·Flange connection: in traditional way, angle steel or common plate flange (C-shaped insert and S-shaped insert) is used to connect air duct sections, and sealing adhesive strip is added between flanges to ensure sealing.

·Flangeless connection: the modern trend, such as TDC (plug connection) connection, uses the air duct plate itself to make male and female mortise for plug connection, simplifies the structure, has good tightness and more concise appearance.

2, Key Performance Parameters and Selection of prepainted metal sheets

The following core parameters need to be considered when selecting the prepainted metal sheets for the ventilation ducts:

·Base plate type and coating weight: commonly used galvanized steel plate (GI). The higher the coating weight (e.g. Z80, Z120), the better the corrosion resistance.

·Coating type of prepainted metal sheets:

·prepainted metal sheets and coils polyester: the most versatile, cost effective, flexible and weather resistant.

·prepainted metal sheets silicone modified polyester: weather and corrosion resistance superior to ordinary polyester, more suitable for outdoor or harsh environment.

·High durability polyester/PVDF of prepainted metal sheets : with excellent weather resistance, UV and pollution resistance, good color durability, commonly used in high-end buildings.

·Coating thickness of prepainted metal sheets : Generally, the total thickness of front coating shall not be less than 20 μ m, and the thickness of back coating shall not be less than 5-7 μ m. The thicker the coating, the stronger the protection.

·Plate thickness of prepainted metal sheets : select according to air duct size and system static pressure requirements, common thickness is 0.5mm-1.2mm.

Example description:

For better understanding, we illustrate two specific scenarios:

Case 1: Modern commercial complex (such as shopping center)

·Scenario description: A shopping mall with a large number of air conditioning supply, return and exhaust systems. Ducts are distributed throughout the suspended ceilings of public areas and in some areas (e.g. atrium, corridors) ducts are exposed as part of the interior design.

·Service condition:

Material Selection: Developer and Designer will select either matte or low gloss ivory white or light gray color rolls. The color shall be consistent with the ceiling and decoration style. Coatings are typically standard polyester or silicone modified polyester because the interior environment is relatively benign and meets aesthetic and durability requirements. Generally, the plate thickness is about 0.6mm.

Application parts:

·SUPPLY/RETURN AIR MAINS DUCTS: in equipment floors or large duct shafts, as main ducts.

·Exposed Ducts: In public areas, ducts are designed for industrial air or direct exposure, with smooth, painted surfaces and uniform color to make them a visual element without the need for additional decoration.

·Smoke Exhaust Ducts: On the premise of meeting fire code requirements (such as fire resistance limits), fire exhaust ducts will be fabricated using thicker base plates and pre painted galvanized steel sheet and coils with special coatings.

Embody of advantages:

·Aesthetics: Unified color improves the overall sense and modern sense of the space.

·Economy: Eliminates the cost of decorative covering outside the air duct.

·High efficiency: factory prefabrication, fast site assembly and shortened construction period.

Case 2: Industrial plant (such as food processing workshop or electronic cleaning workshop)

·Scenario description: Food processing plants are wet and require frequent cleaning, and the air may contain trace amounts of acidic or alkaline substances. Electronic cleaning workshop has high requirements on air cleanliness, and the inner wall of air duct must be smooth, dust-free and corrosion resistant.

·Service condition:

Material selection:

·Food Shop: Galvanized substrates, PVDF coated or high durability polyester pre painted galvanized steel sheet and coils will be selected. PVDF coating has excellent chemical and stain resistance and can withstand repeated scrubbing of cleaning agent. The inner wall of the duct will be coated thicker to ensure integrity.

·Clean workshop: select the prepainted metal sheets without fingerprint treatment. This treatment adds a protective film to the coating, prevents fingerprints and oil from being left when installed and touched, makes it easier to clean, and prevents the surface from becoming a source of dust. Color is usually white to facilitate stain detection.

Application position: the whole air conditioning air supply, return air and exhaust system. Especially, the air supply pipe behind the high efficiency filter has the highest requirements for material cleanliness.

Embody of advantages:

·Corrosion resistance: resistant to moisture and chemicals, extending duct life.

·Easy cleaning: smooth and dense coating surface is not easy to attach pollutants, and can be easily wiped with wet cloth or neutral cleaner.

·Dust-free: The coating is firm and will not pulverize and fall off like ordinary paint and pollute the air.

Summary and Notes

Painted rolls provide a modern solution for ductwork that combines structural functions with decorative effects. The key to its successful application is to accurately select the substrate, coating type and thickness according to the specific service environment (corrosivity, humidity, cleanliness, aesthetic requirements).

Precautions:

·During transportation, handling and installation, take care not to scratch the coating, otherwise corrosion will start from scratch.

·Organic coatings may be damaged at very high temperatures (e.g. above 80 ° C) or in open flames and special coatings should be used with caution or selected.

·For extreme industrial environments with strong acids and alkalis, prepainted metal sheets may not be suitable and other materials such as stainless steel need to be considered.