Carlisle 304156 Water Based Duct Sealant Gray 1 Gallon

Product Description

The CARLISLE 304156 Duct-Seal 321 is an all-purpose, industrial-grade water-based duct sealant designed for sealing metal duct, glass fiber duct board, flex duct, duct fabric, and flexible tubing runouts. Composed of synthetic latex, it is solvent-free and non-toxic, making it appropriate for both residential and commercial HVAC applications. Built-in fiber reinforcement adds structural strength to the cured seal, and UV inhibitors allow for extended outdoor exposure without degradation. It applies between 35 degrees F and 110 degrees F and holds a service temperature range of -20 degrees F to 200 degrees F, covering a wide range of operating conditions. Licensed HVAC technicians and sheet metal contractors are the primary installers of this product.

Duct-Seal 321 is suited for residential and light commercial duct systems where a reliable, code-compliant air seal is required. It bonds to metal spiral and rectangular duct, duct board, and flex duct connections, as well as duct fabric and tubing runouts. Its flame-resistant formulation meets the needs of installations where fire-rated sealant materials are specified. One gallon covers up to 320 linear feet at 3 inches wide and 20-mil thickness, making it efficient for large duct runs or multiple connections in a single service call.

Key Features

• Water-based, solvent-free synthetic latex formula — non-toxic and safe for residential use
• Built-in fiber reinforcement for added mechanical strength at the cured joint
• UV inhibitors extend service life on outdoor or exposed duct sections
• Flame resistant formulation suitable for fire-rated duct sealing applications
• Application temperature range of 35 degrees F to 110 degrees F
• Coverage up to 320 linear feet at 3 inches wide and 20-mil thickness per gallon

Compatibility

Designed for use on all types of metal duct, glass fiber duct board, flex duct, duct fabric, and flexible tubing runouts in residential and commercial HVAC duct systems.

Installation Notes

Installation is typically performed by licensed HVAC technicians or sheet metal contractors. The duct system should be de-energized and the air handler shut down before applying sealant to joints or seams. Apply to clean, dry surfaces within the specified application temperature range of 35 degrees F to 110 degrees F. Allow a full 48-hour dry time before restoring airflow to the duct system. This product is subject to Proposition 65 requirements — consult applicable state and local regulations before use.

Technical Specifications

• Composition: Synthetic Latex
• Color: Gray
• Container Size: 1 gallon
• Coverage: Up to 320 linear feet at 3 inches width, 20-mil thickness
• Application Temperature: 35 degrees F to 110 degrees F
• Service Temperature: -20 degrees F to 200 degrees F
• Dry Time: 48 hours
• Flame Resistant: Yes
• UV Resistant: Yes
• Shelf Life: 1 year unopened
• Length: 7.75 inches
• Width: 7.75 inches
• Height: 7.5 inches
• Weight: 10.75 pounds
• Country of Origin: USA
• Prop 65: Yes

Standard Information

• Brand: CARLISLE
• Manufacturer Part Number: 304156