All panel joints and corner angles of cold rooms shall be sealed with gun applied butyl mastic (non-hardening sealant) on the external (warm) side to ensure continuity of vapour seal under operating conditions. All joints other than panel to panel, to be trimmed with extruded aluminium frames and finished by silicone sealant.
- Provide a seal to a joint in the insulated envelope to prevent the formation of a dirt trap which cannot easily be cleaned
- Accommodate the full range of movements of the joint without splitting or debonding from the faces of the joint
- Accommodate cyclical movements of the joint without fatigue failure
- Have a hardness appropriate to the location and width of the joint
- Have a wear resistance appropriate to the location of joint
- Be chemically compatible with the surface of material to each face of the joint
- Be designed so as not to impart a taint to stored food stuffs
- Be chemically resistant to spillage and cleaning materials
- Not to harbour or encourage biological growth.
- Resist the passage of water vapour as appropriate.
- Permit as appropriate the escape of water vapour to prevent the build-up of ice in joints
Vapour Seals and Barriers
To resist the infiltration of atmospheric water vapour into the insulant core of the insulating sandwich panel and the temperature controlled enclosure a continuous and impervious barrier is essential and can be linkened to the hull of a ship. No single item of design or execution is more important in the construction of a temperature controlled facility, particularly for sub-zero applications. An ineffective vapour barrier will allow water vapour to penetrate, condense and freeze within the insulant core material or on the internal surfaces so degrading the insulant leading to possible delamination and collapse.
Metal facings of insulating sandwich panels are impervious to water vapour transmission, however wherever panels are joined to other panels or to the floor the joint must be designed and act as a vapour barrier incorporating a vapour seal which must be installed with extreme care to ensure vapour impermeability
With regard to cold store construction there is a view that panel to panel sealing should be continuous only on the warm side, i.e. panels should not be sealed on the chamber side. Proponents of this view believe that this allows any water vapour penetrating the external vapour barrier to pass through the panel joint and sublimate on the evaporator coils particularly with respect to ceiling panels as in practice they are the most likely suffer vapour barrier failure during or after erection.
Enclosed environments operated at higher termperatures such as chill stores, banana ripening rooms and food processing facilities may due to hygiene considerations, require joints to be sealed on the inside face as well as the external face. The possibility of vapour pressure differential reversal due to seasonal temperature changes resulting in the outer face of the insulated envelope becoming cold face could also dictate a requirement to seal the inside face of panel joints. In these situations the integrity of the vapour barrier on the warm side is of paramount importance as any leakage will result in a waterlogged panel.