The box frame of the rooftop air-conditioning unit adopts a special-shaped steel skeleton structure. The box panel adopts a double-layer panel structure with an insulation layer in the middle. The inner panel is made of high-quality galvanized steel plate with a thickness of δ≥0.5mm, and the outer panel is made of cold-rolled steel plate with electrostatic powder spraying treatment. The thickness of the inner wall panel is 0.8mm, and the thickness of the outer panel is 1.0mm. The insulation layer is made of high-pressure polyurethane foam, and the insulation density must be ≥48.1kg/m3. The thickness of the insulation layer should ensure that there is no condensation dripping on the surface of the box when the unit is running. The thickness of the panel and the insulation layer should not be less than 50mm. The air leakage rate of the unit should be ≤1%, and the noise outside the unit should be ≤75.1dB (1 meter away from the air conditioner). The outer surface of the roof-mounted air-conditioning unit box should have no obvious scratches, rusts and indentations, the surface should be smooth, the coating should be uniform, the color should be consistent, and there should be no flow marks, bubbles or peeling. If the cabinet is shipped in bulk and assembled on site, the final installation effect should be completely consistent with the external and internal quality of the factory assembly. answer