Pipes and tubular conduits – Distinct layers – With intermediate insulation layer
Patent
1992-10-30
1995-08-15
Bryant, III, James E.
Pipes and tubular conduits
Distinct layers
With intermediate insulation layer
138147, 138151, F16L 914
Patent
active
054410835
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an insulation system for a conduit or container having a surface temperature below the dew point of the ambient air and comprising an inner layer, a heat-insulating layer located on the exterior side of the inner layer and an outer layer located on the exterior side of the heat-insulating layer. In particular the invention relates to an insulating system for insulating cold pipes and conduits and containers for the transportation or storage of cooling media.
2. The Prior Art
It is well-known to insulate hot water pipes by mounting thereon a tubular insulation comprising axially slotted tubular insulating elements. Such tubular insulations are readily mounted and they are effective for preventing loss of heat from the heating pipes.
If such tubular insulations are used in connection with cold pipes, moisture inevitably penetrates through the insulation by diffusion and gets into contact with the surface of the cold pipe. If the surface temperature is below the dew point of the ambient air, condensation of water vapour on the cold pipe will occur and thereby the insulation material becomes moist and-loses its insulating capacity. Furthermore, the insulating material may decompose and the cold pipe may corrode.
The removal of moisture from the insulating material normally takes place very slowly as conventional insulation materials have little capillary effect.
The result is that the tubular insulation remains moist.
The exterior surface of such tubular insulations are usually covered by a layer of a vapour-proof material, such as an aluminium foil or a plastic film, in order to slow down the moistening of the insulating material.
However, experience shows that unavoidable flaws in the vapour-proof foil or film result in severe moistening of the insulating material over the years, and unfortunately in this situation the vapour-proof layer will prevent drying of the heat-insulating layer by capillary suction.
Up to now the only solution to this problem has been periodic replacement of the wet insulation.
SE-C-123644 discloses an insulating system comprising an inner sealing layer, e.g. consisting of asphalt, a heat-insulating layer composed of adjacent elements of trapezoidal cross-section and located on the exterior side of the inner layer and an outer sealing layer, e.g. consisting of asphalt.
It is the object of the invention to provide an insulation system for conduits and containers of the above-mentioned type which instead of preventing water vapours from entering the insulation system, ensures that moisture present therein is continuously removed therefrom.
SUMMARY OF THE INVENTION
This object is obtained with the insulation system according to the invention wherein both the inner layer and the outer layer are water absorbing and are in mutual contact through an opening in the heat-insulating layer, such that water can be transported from the inner layer to the outer layer by capillary suction.
When condensation occurs on the exterior side of the conduit or container, the capillary suction will cause the condensed water to be sucked out by the outer layer of water-absorbing material and to evaporate from the latter layer.
If the insulation material used has a high water vapour permeability, such as mineral wool, the insulation system of the invention preferably further comprises a diffusion-proof layer provided on the exterior side of the heat-insulating layer within the outer water-absorbing layer and having an opening formed therein.
In this embodiment of the invention the diffusion-proof layer will provide a desired high degree of resistance to the diffusion of water vapour from the surroundings and towards the relatively cold surface of the conduit or container.
However, if the insulation material has a low water-vapour permeability, such a diffusion-proof layer may be omitted.
When the opening in the heat insulating layer is in the form of an axially-extended slot, the two layers of water-absorbing material p
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Bryant III James E.
Hygrowick-International APS
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