The firm of Hammel, Green and Abrahamson Inc., an integrated architecture, engineering and planning company, is responsible for the HVAC system design along with other mechanical systems at Schreiber Foods. The company is not only concerned with the HVAC system, but the success of the duct liner installation.

“For most ducting projects of this type we typically specify a polyimide foam liner for the supply ducting and a fiberglass liner for the return,” said Kevin Pope, senior mechanical engineer and vice president at HGA. “The reason for this is any fibers coming off the fiberglass liner are captured in the air handling filtration system before it reenters the supply air. It’s also a way to keep cost down since fiberglass is less expensive and offers reasonable sound attenuation.”

The polyimide foam is generally coated with an acrylic-type polymer when used for duct liner. The coating provides a protective barrier against dust and moisture from collecting in the duct. However, one of the drawbacks to the polyimide foam can be more expensive than other materials.

J. F. Ahern Co. is the mechanical contractor for the project and responsible for the sheet metal and other mechanical systems. Shaun Neubauer, project manager for J.F. Ahern, has as one of his primary functions the need to control project costs.

“It’s part of my job to control project costs, so I begin immediately looking for alternative material choices,” said Neubauer. “We noticed immediately that the polyimide foam cost was coming in rather high and we began investigating alternative duct liner material. We had an opportunity to meet with Ductmate Industries to compare their new PolyArmor polyester-based liner material.”

PolyArmor is new to the market, having been out less than two years. It is a polyester duct liner used in forced air heating, ventilating, and air conditioning systems. The company said it is engineered to provide industry leading R-values, reduce noise, and provide indoor air quality. 

 The polyester material is webbed into a thermal blanket which is then bonded with an FSK facing to resist damage during system installation and operation. It also helps to provide durability in the airstream.

Neubauer said the PolyArmor met the specification requirements and he was nicely surprised with the cost estimate. Since the polyimide was specified, he submitted the PolyArmor cost saving and specifications to Pope and requested a substitution, which was approved.

J. F. Ahern and Neubauer have a long history working with Ductmate Industries. Quite often they specify other Ductmate products like access doors, connectors, and vane systems. Their relationship was a key factor in their decision to install the new PolyArmor liner material.

More emphasis was placed on noise reduction than insulation values, although both were important. The PolyArmor proved for sound attenuation with a .65 NRC rating while also delivering a R5 insulation value in 1-in material thickness.

Duct sizes vary, having dimensions up to 6-ft by 3-ft, and handling an air flow of up to 80,000 cfm. The specifications called for the PolyArmor installed approximately 20-ft downstream from each VAV discharge connections.

 Chris Elwing, Shop Manager for J.F. Ahern, was impressed with the installation performance of PolyArmor. With over 31 years working the sheet metal industry with 13 of those with J.F. Ahern, he’s seen his share of duct insulation.

“We install all duct liners at the shop and have had to use elastomeric-type product for many of our installation,” said Elwing. “Elastomeric material is tough to work with because it’s hard to cut and shape into place.”

Elwing estimated that they installed 25,000 sq ft of the liner material, all installed by hand using no coil machine. Even with the additional labor time required, he says he cut his installation time by 30% or more.

The PolyArmor liner is installed to the duct surface using water-based adhesives. This eliminates the need for solvent-based bonding agents that emit VOC’s for many years after installation. The polyester base material does not promote or support the growth of mold or mildew making it more desirable for a healthy environment and occupant safety.  

The net result was even better than expected.

Neubauer said, “Not only did we reduce costs for the liner material, we saved another 30% on installation time, which is significant.