Practical process information
The principles of insulation drying:
Using the excess pressure procedure, dry heated air is flooded into the insulation layer through special openings.
In the course of the venting phase the dry air is saturated with moisture from the insulation layers before escaping into the room through open border joints or other discharge openings and then dried again using previously installed dehumidification units.
By means of this cycle, drying to the material-specific equilibrium moisture content is achieved.
Using the low-pressure procedure, this entire process is reversed. The humid air is extracted from the insulation layer using vacuum turbines.
This way, a vacuum is created in and around the insulation layers, which balances itself out due to trailing room air dried by dehumidification devices through open border joints or other discharge openings.
Excess pressure is not equal to low pressure!
In order to suck in a certain air volume, for instance 100 m³ at a counter-pressure of 100 mbar (e.g. styrofoam™, mineral wool), approx. 20 % more energy is required than for flooding the same amount of air into the insulation layer at the same counter-pressure (100 mbar). At a counter-pressure of 150 mbar (e.g. perlites) the discrepancy increases to 30 %.
Or in other words: Using the excess pressure procedure, an insulation drying unit can flood approx. 20 to 30 % more air volume into the insulations layer than it would be able to suck out with identical set-up using the vacuum process!
Conclusion: For process-related reasons, the achievable area performance of the vacuum process is lower than that of the excess pressure process.
Important information regarding the vacuum process:
This procedure required the use of a filter system, so that i.a. no water or solids can find their way into the compressor. This would lead to blocking of the turbine and thus to the destruction of the device.