The XPS sandwich panels give a guarantee of duration (return on investment) when used in the food industry.
XPS, EPS and PIR as cores of insulating panels
XPS, EPS and PIR: what is the best insulator? The one that insulates better! However, the choice does not depend on personal preferences but on the application that is required. Furthermore, what is reported on the certificates almost never corresponds to the real working condition of food environments. An insulator, in fact, does not maintain its initial characteristics if it is in a humid, wet environment, with joints between the panels more or less sealed in the presence of steam in the air, subjected to external shocks, to intense washing. In this short treatise we want to give some intuitive ideas of what happens to three reference insulating materials: XPS, EPS and PIR.
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Thermal Conductivity
That is the characteristic that is considered the most important, since from an energy point of view it is the one that ensures savings . Since today all the insulating materials are very performing, in a processing room or in a positive temperature storage cell the heat dispersed through the walls is only about 10% of the thermal loads. Furthermore, as can be seen from the video, in a test we performed an ice cube melted to heat at the same time for XPS and PIR (which in this test are comparable), while the EPS in this case isolated much worse. The important thing is that the real ability to isolate that creates difference between the insulating materials is not seen in the ideal conditions of the test, but in the conditions of humidity and water absorption in which the material operates.
Environmental conditions affect insulating capacity.
Water Absorption
It is intuitive to think that if the water does not isolate well, the island’s insulating material is contained in the foam and worse. This is particularly important in rooms where frequent washing is done or, in any case in which the environment is wet, such as food environments. Even the vapor contained in the air, when it condenses, becomes water and worsens the insulating characteristics. The film shows that by injecting colored liquid into an insulating cube, the EPS lets it penetrate inside, while the polyiso and the XPS make it exit from the same hole from which it entered. The EPS has holes in it. For the other two products the characteristic values are determined by WL (T) i: Long-term water absorption by immersion for XPS & lt; 0.7% for PIR & lt; 2%.
This difference is seen in the long term in the photo of PIR panels.
Steam Permeability
The permeability to the reference vapor (mu) is approximately: in the EPS 20-80, in the XPS 100-200 and in the Polyiso 80, and indicates the resistance to the passage of steam with respect to the air. It is noted that the EPS offers little resistance, while the XPS allows very little steam to pass. Polyurethane has an intermediate value with approximately twice the absorption of the XPS. In the video we can see this behavior empirically, having placed the three insulators on a kettle. At the joints the steam, pushed by the temperature difference, creeps between the panel and the panel, and so impregnates the exposed part that loses its insulation characteristics.
The loss of isolation can be seen from the thermography of joints made of Polyurethane.
Resistance to Compression
We all know how easy it is to hit the sandwich panels inside a factory, for example due to the intense use of trolleys. The panels tend to deteriorate and, if the surface sheet is broken and the paint is removed, even to rust. The impact resistance of the various types of insulating materials can be seen empirically from the video. It should be noted that the Polyiso foam has a strong propensity to breakage due to impacts: by dropping a weight of one kilo, it sticks into the foam and remains stuck. The EPS, even if it has a low resistance to compression, is very elastic and therefore the weight rebounds without creating particular damages. The XPS is the most resistant of the analyzed materials: the hole created is about half of that on the Polyiso and similar to that of EPS.
The XPS panels are therefore more resistant than the PIR ones (see picture).
