Duro Dyne 21042 Butyl Rubber Gasket 3/16 Inch Thick 25 Ft Gray Duct Flange Seal

Product Description

The Duro Dyne 21042 is a butyl rubber gasket designed to seal flanged transverse duct connections in commercial and residential HVAC systems. It comes in a 25-foot roll and measures 3/16 inches thick by 5/8 inches wide. The gray butyl rubber material is permanently soft and pliable, allowing it to compress between two mating flanges and fill gaps, voids, and surface irregularities. This compression creates a flexible, airtight, and moisture-resistant seal that holds up over time without hardening or cracking. HVAC sheet metal workers, duct fabricators, and mechanical contractors rely on butyl rubber gaskets like the 21042 during ductwork installation and retrofit projects. The gasket is applied to one flange face before assembly. When the flanges are bolted or clipped together, the material compresses and bonds to both metal surfaces, eliminating air leakage paths. Duct air leakage is a major source of energy waste in forced-air systems. Leaky duct joints can also generate noise as air escapes under pressure. Using a quality butyl gasket at every flanged connection reduces both problems. The Duro Dyne 21042 is rated for temperatures from -40 to 249 degrees Fahrenheit, making it suitable for supply, return, and exhaust duct applications across a wide range of system types. It adheres to clean, dry metal surfaces and does not promote corrosion on galvanized or painted steel duct. This gasket is domestically manufactured and meets the requirements for use in UL-classified duct construction assemblies. It is a dependable choice for TDC, TDF, and drive-slip duct flange systems where a code-compliant, long-lasting seal is required.

• Butyl rubber construction stays permanently soft and flexible for long-term duct joint sealing
• Temperature rated from -40 to 249 degrees Fahrenheit for broad HVAC application compatibility
• Compresses between flanged duct connections to eliminate air leaks, energy loss, and duct noise

Product Highlights

The Duro Dyne 21042 butyl rubber gasket delivers a reliable, airtight seal at flanged duct joints across a wide temperature range. It is a trusted solution for HVAC installers working with TDC, TDF, and similar duct flange systems.

Product Information

Standard Information

• Brand: DURO DYNE
• Manufacturer Part Number: 21042

Technical Specifications

• Material: Butyl Rubber
• Color: Gray
• Length: 25 ft
• Thickness: 3/16 inches
• Width: 5/8 inches
• Temperature Rating: -40 to 249 degrees F
• Domestic/Import: Domestic