Single glass panel for fire door and double glazed glass panel for fire door

A double glazed glass panel for a fire door, comprising:

• a first glass sheet that has two surfaces, at least one of the surfaces being obtained by forming a first heat reflecting coating thereon, and of which a surface compressive stress is 20 MPa or more and less than 80 MPa;
• and
• a second glass sheet that has two surface, at least one of the surfaces being obtained by forming a second heat reflecting coating thereon, and of which a surface compressive stress is 20 MPa or more and less than 80 MPa, wherein
• the first glass sheet and the second glass sheet are arranged in parallel to face each other with a gap therebetween such that these surfaces on which the first and second heat reflecting coatings are formed are inside, these surfaces being defined as inner surfaces of the first and second glass sheets,
• emissivities of the first and second heat reflecting coatings are set to be 0.07 or less, and
• each of the first and second heat reflecting coatings is formed with at least two layers of silver, which are defined as a lower Ag layer and an upper Ag layer,
• the lower Ag layer is directly deposited on the inner surface of each of the first and second glass sheets such that no layer intervenes between the lower Ag layer and the inner surface,
• under a condition where a test flame is placed at either side of the first glass sheet or the second glass sheet, the double glazed glass panel satisfies the ISO 0834 flame insulating performance test.