Which insulation should I choose – rubber or polyethylene?

Very often, it is difficult for our customers to decide which insulation to choose – rubber or foam polyethylene. Many people start counting the economy without paying attention to other differences.

Cheap – does not mean saving, and it can be justified!

Impact from mechanical loads. Foam rubber insulation is said to be very responsive to external mechanical loads compared to foamed polyethylene. But when the task of thermal insulation of pipelines is not the task to mount insulation as strong as concrete. The insulation has another task-to be elastic, especially when installed on refrigeration units, where insulation made of foamed polyethylene significantly loses.

"Rubber is more expensive than polyethylene." And it's true. But let's think that the price is not the most important thing, the main thing is that the problem is solved. First, we will think about the durability of the material, maintaining energy efficiency, and then we will think about the price. If we take, for example, refrigeration equipment, the cost of rubber insulation in comparison with the cost of the entire system is just a penny. The main task of insulation is to protect the process equipment. And if the foamed polyethylene does not cope in some places – it threatens with heat loss of the entire system. And as a result, freezing of the equipment and subsequent repairs.

Let's move on to the thermal conductivity indicators. Foamed polyethylene and foamed rubber have almost the same thermal conductivity. But if you look deeper, at different temperatures, the thermal conductivity of polyethylene and rubber significantly change. So, for heating pipes, where the heat carrier has a low temperature, foamed polyethylene can also be suitable. But in fact, the indicators that are indicated in the technical characteristics show only the lower value of the properties of a particular insulation. The main influence on such an indicator as thermal conductivity is affected by the presence of air pores in the insulation itself. In the production of foamed polyethylene and foamed rubber, they have "plus or minus" the same number of pores, which, of course, does not affect the coefficient of thermal conductivity. Therefore, in this paragraph, we will adhere to the opinion that it does not matter in such a request – foamed polyethylene or foamed rubber.

The thickness of polyethylene and the thickness of foam rubber. With the same thermal conductivity characteristics of foamed polyethylene and foamed rubber, the same. But for refrigeration systems, where the main role is played by the coefficient of thermal conductivity at low temperatures and vapor resistance – pipe or sheet insulation made of foam rubber – wins.

Water vapor diffusion resistance. This indicator is abstract, since no one has measured these indicators in full-scale conditions for ten years. Here, foam rubber insulation wins, but only in the right and important projects.

When gorenje insulation emits gas. Let us also consider this hypothesis. When gorenje foam rubber is burned, it emits black smoke, which can be eliminated. Foamed polyethylene, however, releases a dangerous compound – carbon monoxide-when ignited. Statistics show that in the production of a fire in the first place, the danger is not from smoke, but from gas poisoning! And if you look at the flammability group, then foamed polyethylene burns remarkably well in full-scale conditions, in contrast to foamed rubber, which has a flammability group of G1.

Moisture penetration. There is an opinion that the foam rubber insulation is impervious only in the upper layers. But, as practice shows, foam rubber insulation has a uniform structure and, therefore, moisture does NOT evenly penetrate the entire thickness of the layer.

Stickiness to the material. Many novice installers are ready to claim that it is much easier to glue insulation made of foamed polyethylene than insulation made of foamed rubber. But experienced installers know that this is only a matter of cunning and rubber insulation is much more elastic and flexible to install, unlike polyethylene.

Gluing seams. Foam rubber insulation lends itself better to technical insulation glue than foamed polyethylene. Why? Again, it depends on the physical characteristics of the material itself.

Shrinkage of the insulation. It has already been revealed experimentally that the insulation made of foamed polyethylene eventually shrinks to 3.5%. We take the insulation length of 1 m - % shrinkage will be 35 mm. And this is quite impressive. Unlike foamed polyethylene, foamed rubber does not shrink this way.

To sum up. Above, we have given all the reasons for choosing insulation made of foamed polyethylene and foamed rubber. We do not insist on choosing one of them. The most important thing is that you make the choice consciously and competently and let your engineering systems last a long time!

Voznyuk Anna