Atco 070-R4.2_9X25FT Flexible Air Duct R4.2 9in X 25ft

Product Description

The ATCO RUBBER PRODUCTS 070-R4.2_9X25FT is a Class 1 insulated flexible air duct designed for residential and light commercial HVAC distribution systems. The duct measures 9 inches in diameter and comes in a 25-foot length, offering R4.2 thermal performance via a thick blanket of fiberglass insulation wrapped around a 2-ply polyester inner core. The air-tight inner core prevents fiberglass erosion into the airstream, while the encapsulated wire helix keeps the duct intact when cut to length. Rated for 5000 FPM air velocity and 6 inches WG positive pressure per UL 181, this duct is built for reliable, low-friction airflow delivery. Licensed HVAC technicians and sheet metal contractors are the primary installers.

This flexible duct is suited for trunk-and-branch and radial HVAC distribution layouts in residential new construction and retrofit applications, as well as light commercial installations governed by IMC, IRC, UMC, and NFPA 90A and 90B. The plain end configuration allows for direct connection to standard round duct collars, boot fittings, and flex connectors without additional adapters. The gray polyester jacket resists tearing and puncture during handling and routing through tight spaces. The compact carton format simplifies jobsite staging and warehouse storage.

Key Features

• R4.2 thick blanket fiberglass insulation for energy-efficient thermal performance
• Air-tight 2-ply polyester inner core eliminates fiberglass erosion into the airstream
• Encapsulated wire helix maintains duct integrity when cut to length, speeding installation
• Smooth inner core reduces friction loss and lowers system operating costs
• Rated 5000 FPM air velocity and 6 inches WG positive pressure per UL 181
• Meets UL 181, NFPA 90A and 90B, IMC, IRC, UMC, HUD, and ASTM C-158 standards
• Gray polyester jacket resists tearing and puncture for low-maintenance service life

Compatibility

Designed as an OEM-style Class 1 flexible air duct replacement or new-installation component for residential and light commercial forced-air HVAC systems using 9-inch round duct connections.

Installation Notes

Installation should be performed by a licensed HVAC technician in accordance with IMC, IRC, NFPA 90A and 90B, and local mechanical codes. Shut down and lock out the air handling unit before connecting or disconnecting any duct sections. Secure all connections with approved clamps or draw bands and seal with listed mastic or UL 181B-listed tape — do not use standard cloth duct tape. Avoid sharp bends or kinking, as excessive deflection reduces airflow and can damage the inner core.

Technical Specifications

• Diameter: 9 inches
• Length: 25 feet
• Insulation Type: Thick Blanket Fiberglass
• Insulation R-Value: R4.2
• Core Material: 2-Ply Polyester
• Jacket Material: Gray Polyester
• Air Velocity Rating: 5000 FPM
• Rated Positive Pressure: 6 inches WG per UL 181
• Rated Negative Pressure: 0.75 inches WG per UL 181
• Temperature Rating: -20 to 180 degrees F continuous, -20 to 250 degrees F intermittent
• Flame Spread Index: 25 maximum
• Smoke Developed Index: 50 maximum
• Duct Class: Class 1
• End Type: Plain End
• Applicable Standards: UL 181, NFPA 90A and 90B, IMC, IRC, UMC 10-1, HUD, ASTM C-158

Standard Information

• Brand: ATCO RUBBER PRODUCTS
• Manufacturer Part Number: 070-R4.2_9X25FT