According to the German building-energy law, heating systems must be properly insulated. For many components such as pumps, valves or fittings, prefabricated insulation boxes made from foam are already available, which are easy to install and remove. However, as these are flammable, it is not possible to fit them everywhere. Insulation with non-combustible materials has, until now, been costly and laborious. For pipelines, non-combustible pipe shells made from mineral wool with an aluminum jacket are now considered state of the art. For more complex system components such as valves or stopcocks — which have to be insulated with non-combustible materials — aluminum boxes are usually used, which are filled with mineral wool at the construction site in a time-consuming process. Alternatively, foam-glass half shells are used. Their production is, however, heavily odorous. They are relatively expensive and, in practice, difficult to process.

Inexpensive and removable insulation boxes made from polymer foams (e.g., PU foam, PP foams) that are already established on the market only achieve, at best, the construction-material class ‘flame-retardant’. “Our aim was to achieve a comparably simple and economical solution with the construction-material class ‘non-combustible’ (A1). In a previous project, we had already successfully developed a non-combustible construction foam. In the follow-up project, we worked with the companies GWK Kuhlmann ((Equipment manufacturer) and IGP Chemie GmbH (Foam manufacturer) on the further development and optimization of both the foam and the process for the manufacture of insulation boxes,” reported Dr. Torsten Kolb, Project Manager at the Fraunhofer WKI.

At the beginning of the project, the material exhibited a comparatively high thermal conductivity of 75 mW/mK at a density of 220 kg/m³. By adjusting the foaming process, additives and surfactants, it was possible to halve the density and significantly improve the thermal conductivity. This, however, initially increased the fire load, as a result of which only class A2 was achieved. During the further course of the project, the researchers succeeded in optimizing the formulation to such a degree that the highest European construction-material class A1 in accordance with DIN EN 13501-1 has now been achieved, with simultaneously good insulation performance (below 60 mW/mK) and low bulk density (below 150 kg/m³). Furthermore, it was possible to verify that approx. 10 percent recycled material, which had been shredded again, could be added to the original formulation without causing a significant deterioration in the characteristic values.

For the project, a prototype system was built at the premises of project partner GWK Kuhlmann, with which the new process for the manufacture of non-combustible, molded-foam insulation components could be tested in practice for the first time. The system reproduces the entire manufacturing process: from preparing, dosing and mixing the components all the way through to filling the reaction mass into the mold. The central components are a dosing unit, which provides the materials in exactly the right ratio, and a mixing unit, in which they are homogeneously mixed shortly before processing. As a result, the project partners were able to test various material formulations under realistic conditions, evaluate the dosing and mixing behavior, and optimize the process parameters in a targeted manner. In addition, the first prototype insulation caps were produced, with which it was possible to demonstrate the fundamental suitability of the process for subsequent industrial production.

The new system offers great potential for application in building construction, in special buildings, and in industrial plants with high temperatures and stringent fire-protection requirements.