What's the Application of cast polyurethane foam in polyurethane sandwich?
The second option for insulating a building structure with polyurethane foam is to pour the mixture into a cavity set aside specifically for this purpose. A striking example is the frame house built using the "sandwich" technique.
This type of work also requires experts with knowledge of certain nuances and extensive experience. These ingredients are also supplied under pressure, but significantly less than when sprayed on a wall. The mixing takes place in a special chamber of the gun, from which the mixture is supplied to the outlet, into the supply pipe. The device can be used in the same way as spraying, with only some reconfiguration of parameters. However, in order to achieve high-quality working performance, there are also special filling devices, which can use special components and have the option of "delayed start" foaming, so that there is enough time to introduce the mixture into the container. The cavity (mold) before active changes in composition structure begin.
In foam-filled structures, holes are left or pre-made for inserting supply tubes into the cavities and for visual monitoring of fill levels. The qualifications of the master are very important here - you need to fully understand the properties of the mixture being prepared: its expected volume expansion, the time for complete volume expansion and the onset of hardening. The operator must carefully maintain a balance between incomplete or loose filling of the cavity and possible cracking or deformation of the insulation structure. Often, complete visual control in this case is not possible, and the mistakes made can only be identified during the operation of the building or with the help of special equipment (thermal imagers).
To insulate the external closed structure, polyurethane foam with a closed-cell structure is used exclusively. To create a sound barrier on interior walls or ceilings, from an economic point of view, cheaper open-cell polyurethane foam can be used.