Quietflex 1640 Flexible Air Duct R4.2 16in 25ft

Product Description

The QUIETFLEX 1640 is a round, insulated flexible air duct rated R4.2, designed for residential and light commercial HVAC distribution systems. The duct features a rip-stop silver polyester vapor barrier jacket, a galvanized metal spiral core, and formaldehyde-free fiberglass insulation. It is 16 inches in diameter and comes in a 25-foot length, making it well suited for trunk-to-register runs in forced-air systems. With a maximum airflow rating of 6,000 CFM, it handles high-volume air distribution without restriction. Licensed HVAC technicians and sheet metal contractors are the primary installers of this product.

This flexible duct is intended for use in residential and commercial forced-air HVAC systems where a round, insulated duct connection is required. The oversized core is sized to fit standard collars and register boxes, reducing the need for adapters on most common installations. It is packaged in weather-resistant bagged packaging for jobsite storage. The product meets HUD/FHA standards 515.2.1 Paragraph B, NFPA 90A and 90B, BOCA standards, and City of Chicago requirements, as well as most federal, state, and local codes. Greenguard Certified insulation supports indoor air quality compliance on qualifying projects.

Key Features

• R4.2 formaldehyde-free fiberglass insulation for thermal performance in conditioned spaces
• Rip-stop silver polyester vapor barrier jacket resists tearing during installation and routing
• Galvanized metal spiral core maintains round cross-section and supports airflow up to 6,000 CFM
• Oversized core fits standard collars and register boxes without additional adapters
• UL 181 Class 1 listed and Greenguard Certified
• Weather-resistant bagged packaging for jobsite and storage protection

Compatibility

Designed as an OEM-style replacement and new-installation flexible duct for residential and light commercial round-duct HVAC systems requiring a 16-inch diameter insulated duct section.

Installation Notes

Installation should be performed by a licensed HVAC technician or sheet metal contractor in accordance with NFPA 90A, NFPA 90B, and applicable local mechanical codes. Shut down and lock out the air handling unit before connecting or disconnecting duct sections. Secure both ends of the duct with approved sheet metal screws and UL 181B-listed mastic or tape. Avoid sharp bends and excessive compression of the duct body, as both reduce effective airflow and can damage the insulation layer.

Technical Specifications

• Diameter: 16 inches
• Length: 25 feet
• R-Value: R4.2
• Duct Shape: Round
• Maximum Airflow: 6,000 CFM
• Jacket Color: Silver
• Jacket Material: Polyester (rip-stop vapor barrier)
• Core Material: Galvanized steel
• Insulation: Formaldehyde-free fiberglass
• Listing: UL 181 Class 1
• Certification: Greenguard Certified
• Standards: ASTM C518, NFPA 90A, NFPA 90B, HUD/FHA 515.2.1 Paragraph B, BOCA

Standard Information

• Brand: QUIETFLEX
• Manufacturer Part Number: 1640