Fire-rated ventilation duct and improvements therein

1. 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.

2. The fire-rated ventilation duct assembly as claimed in claim 1 , wherein said first connection section and said second connection section for said inner liner comprise a slip-on liner spacer section having a broken J-profile, and each of said slip-on broken J-profile liner spacer sections being configured for coupling and connecting to a respective traverse edge of said inner liner, so that said fire-rated ventilation duct section comprises a field-modifiable configuration.

3. The fire-rated ventilation duct assembly as claimed in claim 1 , wherein said first connection section and said second connection section for said inner liner comprise one or more slip-on liner spacer sections, each having a broken L-profile, and each of said slip-on broken L-profile liner spacer sections being configured for coupling and connecting to a respective traverse edge of said inner liner, so that said fire-rated ventilation duct section comprises a field-modifiable configuration.

4. The fire-rated ventilation duct section as claimed in claim 1 , wherein said inner liner is formed from a continuous strip of metal spirally wound on a machine to form a continuous tube having one of a round cross-section profile or said oval cross-section profile.

5. The fire-rated ventilation duct section as claimed in claim 1 , wherein said inner liner comprises a substantially circular cross-section profile and said outer casing comprises a substantially circular cross-section profile.

6. A fire-rated duct section comprising:

an inner liner configured as a conduit for air movement, said inner liner comprising a metallic material and having a first end and a second end, and said first end including a first spacer section, and said second end including a second spacer section;

said inner liner having substantially circular cross-section profile;

an outer casing configured for encasing said inner liner, said outer casing comprising a metallic material, said outer casing having a first end and a second end, and said first end including a first duct connection section configured for joining one end of a second fire-rated ventilation duct, and said second end including a second duct connection section configured for joining one end of a third fire-rated ventilation duct;

said outer casing having substantially circular cross-section profile;

an insulation layer configured to provide a thermal insulation layer between said inner liner and said outer casing, and said first and said second spacer sections 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 spacer 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 spacer section of said inner liner to form a sealed duct section.

7. The fire-rated duct section as claimed in claim 6 , wherein said outer casing comprises two or more outer casing panels configured to be joined together at respective longitudinal edges, and each of said outer casing panels having corresponding traverse edges.

8. The fire-rated duct section as claimed in claim 7 , wherein said first duct connection section and said second duct connection section for said outer casing comprise a spacer section having a broken J-profile formed on each traverse edge of said outer casing panels.

9. The fire-rated duct section as claimed in claim 8 , wherein said metallic material for said inner liner comprises a metallic material having a minimum thickness for a fire-rating according to one or more of an ASHRAE standard, according to the 2016 ASHRAE Handbook, HVAC Systems and Equipment, and a SMACNA HVACstandard, according to the HVAC Duct Construction Standards Metal and Flexible, 3rd Edition, 2005, and wherein said metallic material for said outer casing panels comprises a metallic material having a minimum thickness for a fire-rating according to one or more of the ASHRAE standard and the SMACNA HVAC standard.

10. The fire-rated duct section as claimed in claim 7 , wherein said first duct connection section and said second duct connection section for said outer casing comprise a spacer section having a broken L-profile formed on each traverse edge of said outer casing panels.

11. The fire-rated duct section as claimed in claim 10 , wherein said metallic material for said inner liner comprises a metallic material having a minimum thickness for a fire-rating according to one or more of an ASHRAE standard, according to the 2016 ASHRAE Handbook, HVAC Systems and Equipment, and a SMACNA HVAC standard, according to the HVAC Duct Construction Standards Metal and Flexible, 3rd Edition, 2005, and wherein said metallic material for said outer casing panels comprises a metallic material having a minimum thickness for a fire-rating according to one or more of the ASHRAE standard and the SMACNA HVAC standard.

12. The fire-rated duct section as claimed in claim 6 , wherein said inner liner is formed from a continuous strip of metal spirally wound to form a continuous round tube.

13. The fire-rated ventilation duct section as claimed in claim 6 , wherein said inner liner is formed from a continuous strip of metal spirally wound on a machine to form a continuous tube having one of said round cross-section profile or said oval cross-section profile.