Thermal insulation structure

Claim 2

A double-walled heat insulating structure for use in an application where the high and low temperatures to which the structure will be exposed constitute an operating temperature range comprising: an inner wall; an outer wall spaced from said inner wall; sealing means forming a gas-tight cavity between said inner and outer walls; a polyurethane foam contained within said cavity; and said cavity also containing a free gaseous fluorinated hydrocarbon at a pressure which is maximized without exceeding that at which it will condense in the operating temperature range of the structure.

Claim 3

A double-walled heat insulating structure in accordance with claim 1 wherein: said polyurethane foam is blown with a fluorinated hydrocarbon.

Claim 4

A double-walled heat insulating structure in accordance with claim 2 wherein: said fluorinated hydrocarbon is trichloromonofluoromethane.

Claim 5

A double-walled heat insulating structure in accordance with claim 3 wherein: said polyurethane foam is of the opened-cell type.

Claim 6

A double-walled heat insulating structure in accordance with claim 3 wherein: said polyurethane foam is of the closed-cell type.

Claim 7

A double-walled heat insulating structure for use in an application where the high and low temperatures to which the structure will be exposed constitute an operating temperature range comprising: an inner wall having a heat reflecting film on its outer facing surface; an outer wall spaced from said inner wall; sealing means forming a gas-tight cavity between said inner and outer walls; a polyurethane foam contained within said cavity; and said cavity also containing free gaseous difluorodichloromethane at a pressure which is maximized without exceeding that at which it will condense in the operating temperature range of the structure.

Claim 8

A double-walled heat insulating structure for use in an application where the high and low temperatures to which the structure will be exposed constitute an operating temperature range comprising: an inner wall having a heat reflecting film on its outer facing surface; an outer wall spaced from said inner wall; sealing means forming a gas-tight cavity between said inner and outer walls; a polyurethane foam contained within said cavity; and said cavity also containing free gaseous difluorodichloromethane at a pressure which is maximized without exceeding that at which it will condense in the operating temperature range of the structure.

Claim 9

A double-walled heat insulating structure for use in an application where the high and low temperatures to which the structure will be exposed constitute an operating temperature range comprising: an inner wall; an outer wall spaced from said inner wall; sealing means forming a gas-tight cavity between said inner and outer walls; said cavity containing alternating layers of heat reflecting film and a polyurethane foam blown with a fluorinated hydrocarbon; and said cavity also containing a free gaseous fluorinated hydrocarbon at a pressure which is maximized without exceeding that at which it will condense in the operating temperature range of the structure.

Claim 10

A double-walled heat insulating structure for use in an application where the high and low temperatures to which the structure will be exposed constitute an operating temperature range comprising: an inner wall; an outer wall spaced from said inner wall; sealing means forming a gas-tight cavity between said inner and outer walls; said cavity containing alternating layers of heat reflecting film and a polyurethane foam blown with a fluorinated hydrocarbon; and said cavity also containing a free gaseous fluorinated hydrocarbon at a pressure which is maximized without exceeding that at which it will condense in the operating temperature range of the structure.