Fire-rated ventilation duct and improvements therein

A fire-rated ventilation duct assembly comprising:

• a first duct module, said first duct module including,
• an inner liner configured as a conduit for air movement, said inner liner comprising a metallic material having a specified fire-rating, and said inner liner having a substantially oval cross-section profile and including a first end and a second end, and said first end including a first connection section, and said second end including a second connection section;
• an outer casing configured for encasing said inner liner, said outer casing comprising a metallic material having a fire-rating specification, said outer casing having a substantially oval cross-section profile and including a first end and a second end, and said first end including a first duct connection section and said second end including a second duct connection section,
• an insulation layer configured to provide a thermal insulation layer between said inner liner and said outer casing, and said first connection section of said inner liner further comprising a first liner spacer and said second connection section of said inner liner further comprising a second liner spacer, said first and said second liner spacers being configured to define a cavity for receiving and positioning said insulation layer between an outer surface of said inner liner and an inner surface of said outer casing;
• said first duct connection section of said outer casing being configured to attach to at least a portion of said first connection section of said inner liner, and said second duct connection section of said outer casing being configured to attach to at least a portion of said second connection section of said inner liner to form a sealed duct section;
• and
• a second duct module, said second duct module including,
• an inner liner configured as a conduit for air movement, said inner liner comprising a metallic material having a specified fire-rating, and said inner liner having a substantially oval cross-section profile and including a first end and a second end, and said first end including a first connection section, and said second end including a second connection section;
• an outer casing configured for encasing said inner liner, said outer casing comprising a metallic material having a specified fire-rating, said outer casing having a substantially oval cross-section profile and including a first end and a second end, and said first end including a first duct connection section and said second end including a second duct connection section,
• an insulation layer configured to provide a thermal insulation layer between said inner liner and said outer casing, and said first connection section of said inner liner further comprising a first liner spacer and said second connection section of said inner liner further comprising a second liner spacer, said first and said second liner spacers being configured to define a cavity for receiving and positioning said insulation layer between an outer surface of said inner liner and an inner surface of said outer casing;
• said first duct connection section of said outer casing being configured to attach to at least a portion of said first connection section of said inner liner, and said second duct connection section of said outer casing being configured to attach to at least a portion of said second connection section of said inner liner to form a sealed duct section;
• and
• said second duct connection section of said first duct module being configured for joining the first duct connection section of said second duct module, so that said first duct module and said second duct module are coupled together to form said fire-rated ventilation duct assembly.