| 摘要 |
PROBLEM TO BE SOLVED: To determine whether a product is attained to have a prescribed pressure or not, which is required to show a function of thermal insulating performance, because the thermal insulating performance of low-pressure double- layer glass is dependent on the pressure of an aperture part thereof, in consideration of such tendency that the pressure of the low-pressure double-layer glass used on an opening part of a building or the like is reduced to 10 Pa or less, preferably 1 Pa or less. SOLUTION: The whole low-pressure double-layer glass is heated, and a thermal insulating material having a plane is brought into contact with the whole surface or a part of the surface of one plane glass composing the low- pressure double-layer glass. Then, in the middle of reducing the temperature of the low-pressure double-layer glass up to an ordinary temperature, it is determined whether the pressure of a low-pressure space is below a target pressure or not, by a lowering speed of the surface temperature of the glass surface.
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