Double Wall Round Spiral Duct

Double wall round spiral duct has two different types of applications:

• Acoustical double wall for noise control
• Thermal double wall duct for temperature control

ADMP’s double wall round spiral pipe and fittings are typically manufactured with double wall flange. All sizes shall be defined by the inner shell/inside dimensions.

Acoustical Double Wall

Standard Acoustical double wall is for noise control. ADMP constructs this with a perforated inner shell surrounded by a solid outer shell. In between these two steel, shell walls is a layer of 1”, 1-1/2” or 2” insulation per the engineer specifications or current SMACNA standards. The acoustical duct material has a K factor of .27 Btu/Hr/Sq.Ft./degree F. at 75 degrees Fahrenheit mean temperature. The perforated inner shell has 3/32” diameter holes staggered at 3/16” on center for a clear open area of 23%.

Thermal Double Wall

Standard Thermal double wall is for temperature control. ADMP constructs this with a solid inner shell surrounded by a solid outer shell. In between these two steel, shell walls is a layer of 1”, 1-1/2” or 2” insulation per side.

Solid Outer & Solid Inner Shell

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*PVS specification book available
**Only even sizes will be produced greater than 12” ID (Inside Diameter)

Perforated Inner Shell

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The sound rating of LMK-2775 will be equal to United K-27 duct and fittings since the gauges, hole diameter and percentage free area pattern and acoustical liner are identical.

Specialty Fittings:

Specialty configurations are available upon request. Some examples are as follows: Elbows (75, 15 and other degree angles are also available), a wide variety of different radii are available. Flange connections are available by the following, but not limited to: Angle Rings or, AccuDuct, Spiral Mate. Fittings can have couplings built into their construction. Liners of fittings can be built with an extended coupling to aid field assembly. All fittings can have stop-beads incorporated, unless otherwise specified.

Construction Standards:

As listed in the current SMACNA HVAC Duct Construction Standards. Other regulatory construction standards are available upon request.

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