Adapter for access units of underfloor ducts

Claim 1

A COMPOSITE MULTI-LAYERED INSULATION FOR USE IN A VACUUM SPACE COMPRISING LOW-CONDUCTIVE FIBROUS SHEET MATERIAL LAYERS OF PERMANENTLY PRECOMPACTED PAPER COMPOSED OF FIBERS HAVING DIAMETERS LESS THAN 20 MICRONS, THE PAPER LAYERS CONTAINING FINELY-DIVIDED RADIANT HEAT REFLECTING BODIES OF SIZES LESS THAN ABOUT 500 MICRONS IN AN AMOUNT BETWEEN ABOUT 10% AND 60% BY WEIGHT OF SAID PAPER AND HAVING METALLIC SURFACES BEING UNIFORMLY DISPERSED THROUGHOUT THE PAPER LAYERSS AND SEPARATED BY SAID FIBERS; AND THIN, FLEXIBLE RADIANT HEAT REFLECTING SHIELDS OF LESS THAN ABOUT 0.2 MM. THICKNESS BEING SUPPORTABLY CARRIED IN SUPER-IMPOSED RELATION BY SAID PAPER LAYERS, EACH SHIELD BEING DISPOSED IN CONTIGUOUS AND COEXTENSIVE RELATION ON OPPOSITE SIDES WITH A PAPER LAYER, THE FIBERS OF SAID PAPER LAYER BEING ORIENTED SUBSTANTIALLY PARALLEL TO THE HEAT REFLECTING SHIELDS AND SUBSTANTIALLY PERPENDICULAR TO THE DIRECTION OF HEAT INLEAK ACROSS THE VACUUM SPACE, AND SAID MULTI-LAYERED COMPOSITE INSULATION BEING ARRANGED IN THE VACUUM SPACE TO PROVIDE BETWEEN ABOUT 4 AND 250 PAPER LAYERS PER INCH OF SAID COMPOSITE INSULATION.