Perlite must be dry and packaged in moist-proof bags or sealed tank trucks. (The recommended moist limit is 0.1% by weight).
The perlite packaged in paper bags must not be used.
Field installation of cryogenic perlite for large cryogenic containers requires keeping emptiness in the annular space of the container to be insulated. After the expanded perlite is pressurized in a tank vehicle, it is installed by a combination of emptiness and pressure.
In small applications, where the vacuum transfer is not practice, the dry perlite is installed through mediums other than vacuum, in strictly controlled conditions, in order to achieve satisfactory results.
If insulation is intended in the shortest time possible, the perlite must be kept dry and the interstitial gas must have a low level of humidity adsorption.
Heat transfer through the annular space filled with perlite is a combination of conduit in solids and thermal radiation, whereby gas conduction is also an important transfer mechanism to be taken into account, the interstitial gas pressure must be reduced to a proper level.
Thermal conductivity increases with the increase of the density to atmospheric pressure, but reduces with the increase of density to lower pressures.