Polyurethane Sandwich Roofing Panels - Key Points for On-site Inspection of Foaming Quality
Polyurethane Sandwich Roofing Panels - Key Points for On-site Inspection of Foaming Quality
1. Appearance and Cell Structure
- Observe the cross-section of the panel. High-quality foam should have fine, uniform cells, without obvious large-diameter cells, and free from voids, collapse, or delamination.
- The closed-cell rate must meet the standard (usually ≥90%). This can be achieved through a simple test: lightly press the panel. If it quickly rebounds without significant indentation, the closed-cell rate is relatively high; if gaps appear after pressing or it doesn't rebound easily, it likely has more open cells.
2. Density and Bulk Density Testing
- Randomly select boards and measure their actual thickness using calipers (must match the nominal thickness). Weigh the boards and calculate the bulk density. The bulk density of standard rigid polyurethane foam insulation boards should be between 35–45 kg/m³. Too low a bulk density can lead to a loose cell structure, reducing insulation and compressive strength.
3. Surface Smoothness and Integrity
- The board surface should be smooth, without bulges or cracks, and without missing corners or pieces at the edges. The foam layer and surface layer (if any) should be firmly bonded without any signs of peeling.
4. Preliminary Flame Retardancy Assessment (As Required)
- If the board is flame-retardant, it can be verified through the manufacturer's flame retardancy rating report. A simple flame retardancy test can be performed on-site (caution: lightly heat the edges of the board with an open flame). High-quality flame-retardant boards should self-extinguish upon removal of the flame, without violent burning or molten dripping.