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Zero Clearance Grease Duct


What sets us apart?

Integrated centering sleeve stabilizes the tubes during assembly and covers joint grooves that might otherwise be exposed and trap grease contaminants. Also provides a channel for high temp sealant to accurately insure system water tightness. Extra large spacing between outer wall sections allows for quick and easy installation of the securing band.

  • Construction
  • Specifications
  • Features
  • Literature

Grease Duct - Construction

Fire-rated (DIS3Z) significantly reducing installation footprint and frees up space for other use. No need to build an expensive fire-rated chase or apply two layers of fire wrap typically required for welded steel grease duct designs.

Available in 5"- 36"; 3" wall insulation and single wall. DuraStack Pro is now UL 1978 listed for applications where 1" air insulated, 1", 2", or 4" AES Wool Insulated grease duct is required. Please see the DuraStack Pro product pages for more details. 

UL1978, UL2221 (2 HR)
IMC, UMC and NFPA96 Code Compliance

Blanket insulation is already installed in the portion that lines up with the outside casing. We provide an insulation band to be field installed behind the outside band.

Goes together with the inner flange and inner locking band (with centering extension). The outer locking band is on the outside for more support, making it a stronger system.

DuraVent, Inc. Model DIS3Z grease ducts have been tested and listed by UL to UL/ULC Standards. UL 1978 Grease Duct and UL2221(2 hr Fire Rating). IMC, UMC and NFPA96 Code Compliance.

Grease Duct is subjected to rigorous and stringent requirements of the UL1978 & UL-2221 standard, including continuous firing at 500°F (260°C), plus 30 minute firing at 2000°F (1093°C).

Grease Duct Specs 1 Grease Duct Specs 2


  • Stainless steel construction is highly corrosion resistant and extremely durable.
  • Round tubular design maintains structural integrity significantly longer than a rectangular welded steel product.
  • 0" Clearance grease duct (3" insulation & 2 hours fire rating) eliminates the need for a separate fire-rated enclosure around the duct.
  • Inner casing available in 304 or 316 stainless steel.
  • Outer casing available in 304 or galvalume.
  • Superior flow rate is achieved with round tube construction.
  • Modular design assembles quickly with common tools.
  • Contaminants of combustion are not trapped within the flue like it is commonly found in the corners of a rectangular design, thus making it much easier to clean and reduce the chance of fire from accumulated grease.
  • No safety concerns with having welding on site that could cause a fire.
  • Backed by a comprehensive Limited Lifetime Warranty.