This article was made in cooperation with Armacell.
Cold insulation keeps the cold cold
What has been cooled down once should not be warmed up again – this applies to both old affairs and insulation. When the cold can be kept cold with the help of insulation, not so much energy is needed to maintain the cold temperature.
Everyone knows that you shouldn’t keep the freezer open, otherwise electricity is wasted and the freezer’s performance suffers. The same applies to poorly insulated industrial systems, but on a much larger scale.
Cold insulation has two important goals:
- To insulate so that as little heat as possible is transferred from the surrounding air to the object to be insulated. When thermal insulation prevents the flow of heat from the object to be insulated to the environment, the principle of cold insulation is just the opposite. It limits the heat flow from the environment to the object to be insulated, so that the heat flow does not raise the temperature of the contents.
- To protect the surface from moisture. Cold installations typically struggle with problems caused by moisture. When warm air meets a cold surface, the air’s ability to absorb moisture decreases and causes moisture to accumulate on the cold surface.
In cold insulation, moisture is the enemy
The need for moisture management sets its own requirements for cold insulation materials. The cell of the insulating material used for a cold object should be mainly closed-cell and preferably diffusive, so that air humidity cannot penetrate it. Diffusion refers to a phenomenon where air humidity tends to equalize between different humidity levels.
In addition, for a material with open cells the insulation must be protected against diffusion with a vapor barrier that needs to be intact and that meets the minimum requirements for water vapor permeability. For example, odorless bitumen and bitumen felt or bitumen mat, metal foil or plastic sheet can be used as a vapor barrier. The seams of these materials must be as tight as the material itself for the vapor barrier to do its job.
The vapor barrier is always installed on the warm side of the insulation layer, i.e. on the outer surface. This prevents water vapor from being absorbed into the insulation.
On the other hand, closed-cell insulation like Armacell’s ArmaFlex does not need a vapor barrier. In this case, vapor diffusion resistance is built up through the whole material.
When dimensioning the cold insulation, it is necessary to define the dew point in order to prevent condensation of moisture on the surface of the insulation. The dew point can be calculated based on the air temperature and the relative humidity of the air, resulting in the temperature at which moisture begins to condense on the surface of the object. If the dew point is, for example, 8 ℃, the insulation must be made so that its surface temperature is more than 8 ℃.
Cool tip: Armacell offers a user friendly online tool for all technical insulation calculations. Try it here.
Why do we make cold insulations?
Cold insulations can be divided into three groups based on their main purpose:
- With condensation/anti-sweat insulation, the aim is to keep the surface temperature of the insulation higher than the dew point and thus prevent moisture from condensing on the surface of the insulation.
- In process technical cold insulation, the goal is to keep the temperature of the contents of the object to be insulated within the limits required by the process.
- Economic cold insulation aims for cost efficiency by reducing cold loss and optimizing insulation costs.
Important things to remember when installing cold insulation
As with all insulation, also in cold insulation, careful work, proper tools and equipment, and high-quality insulation materials are important prerequisites for a successful end result.
It is worth paying special attention to insulation penetrations and seam points, so that they become vapor-tight for sure. Each layer of insulation must be installed separately and the seams must be sealed by gluing.
Special precision is also required with supports structures, brackets, valves, pumps and t-joints to avoid the formation of thermal bridges through extra seams.
The pipeline or tank to be insulated must be corrosion protected before the insulation is installed. There is a high risk of corrosion, especially on surfaces with an operating temperature of -10 ℃ or higher, and on pipes that are not in continuous use. On the other hand, a pipeline whose temperature is significantly below the freezing point is more likely to be spared from corrosion.
Now let’s go warm up – but not those old affairs. See you in the next part of the article series!