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Special materials and connectors may be available. Please contact your nearest representative for details. At Spiral Pipe of Texas, our home area of the Central and Southern US encompasses regions with high fluctuations in both temperature and humidity. Duct insulation is also critical in reducing HVAC system noise. Here are some of the product options for round insulated duct that are available from Spiral Pipe of Texas.
Double-wall Insulated Round Ducts Double-wall construction allows you to contain the insulation media between an inner and outer metal shell. The insulation is protected from external damage — a critical concern for ductwork on rooftops and out of the building envelope. Where ducts are exposed to view, insulation is concealed for a more pleasing appearance. The internal metal shell gives protection from insulation erosion, maintains a smooth duct cross-section, and makes cleaning the ducts easier.
Here are some of them. Outer Metal Shell For HVAC air ducts, the outer shell is the structural and pressure containment portion of the product, and is the basis of construction. It is important to note that the dynamic airflow performance of a duct system is based on the inner shell, and most duct sizing on mechanical drawings are I.
Yet, it is the outer shell that determines gauge, reinforcing and construction, as well as defining how a duct fits within the physical constraints of a building. Fitting dimensions elbow centerline radii, tee fitting length, tap clearance to end, etc.
Straight duct construction — available as spiral lock-seam duct corrugated and non-corrugated and welded longitudinal-seam duct.
Fitting construction — fully-welded or tack-welded and sealed. Gauges — 28 to 16 for galvanized spiral lock-seam, 28 to 18 for stainless steel spiral lock-seams, 0. Appearance and finish — standard factory finish no special cleaning, welds spray-painted, mill markings, labels and piece-marks visible , paint-ready welds not painted, removeable labels , and factory painted. SPOT has additional literature giving more specific details for our architectural duct products.
Inner Metal Shell Solid — standard metal liner in gauges and construction to contain the insulation and maintain concentricity and structural integrity.
Available in all materials offered above for outer shells. Perforated metal with erosion barrier — standard perforated material with an additional protective layer of Mylar between the insulation and the perforations opening into the airstream. Insulation Layer Standard Material — our standard product is a 0. The insulation is thicker than the intended annular space between metal shells 1. This material is a highly resilient inorganic glass mineral wool with bio-based binders.
It does not contain phenol, formaldehyde, acrylics or artificial colors. Other thicknesses available. Though sometimes specified, they make duct assembly with slip-fit transverse joints more difficult, create thermal bridges between the interior and exterior of the duct, and have a negligible effect on actual R-value.
In actual practice, insulation compression is more of a concern for larger diameters of duct where double-wall flanges are typically used for transverse connectors, eliminating any need for spacers.
Fiber-free, non-particulating foam alternative to glass fiber insulations. Like our double-wall products, the outer metal shell is the basis of construction. Labor needed for transverse joint assembly can also be reduced since a single slip joint is all that is necessary. The product is ideally suited for systems with long, straight runs of duct — gymnasiums, cafeterias, airports, sports arenas and convention centers.
And we are happy to provide it. Spiral duct has always been green — long before the term came into being. As economies recovered, new and better buildings were incorporating ventilation and conditioning systems that had been developed during the previous few decades.
But they had three problems — energy was expensive, raw materials were also expensive and often in short supply, and there was a shortage of skilled labor with so many young men lost in the war. To solve all three problems, spiral ducts were developed. Round is the most efficient shape for transporting air. Round is also the strongest shape for transporting air.
You need to limit surface deflection to prevent metal fatigue and duct rumble, and metal thickness and additional reinforcement were the ways of accomplishing this with traditional rectangular ducts. Round ducts have virtually no wall deflection in normal operating conditions, and the helical spiral seams strengthen the duct even more.
Spiral ducts are normally produced in longer lengths than rectangular ducts. Where rectangular duct is normally provided in 4 or 5 foot nominal lengths, the standard for spiral duct is 10 feet with lengths as much as 20 feet commonly provided.
So, here we have a product — spiral duct — that uses less energy, less material and less labor than other methods of transporting air. Most spiral duct systems produced at Spiral Pipe of Texas are galvanized steel and, where insulation is required, use fiberglass insulation. Galvanized steel is one of the most recycled materials on the planet.
For our insulated products, our standard for double-wall products is Knauf Friendly-Feel Duct Wrap or an equivalent product. They contain no phenol, formaldehyde, acrylics or artificial colors. Most states, including our home state of Texas, have adopted state-wide energy codes. It calls for ductwork to be constructed to Seal Class A.
Part of the requirement involves the contractor assembling our ducts using sealant, but our duct components themselves meet Seal Class A.
The only mechanical seams that do not have to be sealed under this standard are the spiral lock seams of spiral duct. They have been proven to have almost no inherent leakage. Per this standard, all ducts should be constructed and installed to meet a Duct Leakage Class 4, regardless of whether testing is required or not. Our products greatly outperform the energy codes with only half the leakage that is allowed. These are guides for achieving progressive amounts of energy savings toward a net zero energy building and are available for different building types.
The number of fittings should be minimized and should be designed with the least amount of turbulence produced…. Round duct is preferred over rectangular duct. However, space height restrictions may require flat oval duct to achieve the low turbulence qualities of round ductwork. Using it, you can see the actual performance efficiencies of round and flat oval spiral ducts and fittings over equivalent rectangular ducts. These lower pressure drops optimize the duct system performance and allow the transport of air at lower fan horsepower.
Remember, we meet the version of Standard Our round and flat oval products outperform metal rectangular and nonmetal ducts in true sound attenuation. Turbulence is the main source of airflow generated noise, and our lack of square corners eliminates much of the airflow turbulence. You just might have to do a bit more work. Lower leakage and higher efficiency than the Standard For this credit, you must not generate more than 2. At Spiral Pipe of Texas, our standard practice is to coordinate the project with our customers and produce product and quantities matching our Coordinated Assembly Drawings.
You certainly need to seal the ducts to meet the above requirements. But using a duct system from Spiral Pipe of Texas can reduce or eliminate much of the on-site use of sealants.
Our Triple-Rib gasketed duct system allows you to install sealed ducts without site-applied duct sealants. Even when sealants are used, round and flat oval spiral duct systems typically use far less sealants than rectangular systems. First, there is no longitudinal seam to be sealed since the spiral lockseams are exempted from sealing.
Round and flat oval ducts have smaller perimeters than equivalent rectangular ducts, so there is less transverse sealing. Longer lengths of spiral duct results in less transverse joints to seal in the first place. Finally, the traditional slipfit joints in spiral pipe require less volume of sealant per length of seam than required for most rectangular joint types.
One requirement is to protect absorptive materials stored on-site and installed from moisture damage. Round and flat oval ducts have less airflow generated noise than rectangular ducts, and our double-wall and insulated products increase actual sound attenuation through a duct path.
We also offer a full line of duct silencers. True innovation would be to reverse that trend and design around highly efficient round and flat oval ducts from Spiral Pipe of Texas.
We just usually do it without letting our marketing people put leaves and butterflies on our literature and website. Submittal Downloads.
[PDF Download] HVAC Duct Construction Standards-Metal & Flexible 3rd Edition [Download] Online
SMACNA 006-2006 HVAC Duct Construction Standards - Metal and Flexible, 3rd Edition
HVAC Duct Construction Standards, Metal & Flexible SMACNA – 2005