Perry Fiberglass Products, Inc. is a leading manufacturer of high quality fiberglass reinforced plastic (FRP) products for heating and ventilation systems and industrial exhaust. Whether the application is in commercial HVAC or industrial construction, Perry Fiberglass offers a variety of quality products and superior service. We supply both single wall and pre-insulated double wall duct to meet every ventilation need.

Perry 20S Low Smoke™ Class 1 duct has been approved for direct burial. Typical supply, return and exhaust systems include but are not limited to:

  • Schools
  • Botanical Gardens
  • Super Markets
  • Pools
  • High Rise Offices
  • Parking Garages
  • Churches
  • Zoos
  • Restaurants
  • Hospitals
  • Auditoriums
  • Diesel/Auto Exhaust
  • Libraries
  • Banks
  • Residences

Engineering assistance is available to write a specification for your individual project

Perry Fiberglass offers two main categories of FRP duct products: single wall and pre-insulated double wall.

Single Wall
Perry 20S Low Smoke™, our Class 1 rated single wall duct, meets 25/50 flame/smoke requirements of UL 181. Perry 20S Low Smoke™ is unique in the industry and has found wide acceptance for both industrial and HVAC projects. It is especially desirable in corrosive environments where flame and smoke development is a concern.

Pre-Insulated Double Wall
If thermal control is a concern, then Perry 20S-IR7 pre-insulated double wall duct solves the problem. When supplied with the standard 1" insulation thickness, our double wall duct has a k factor of 0.14 and an R value of 7. The same corrosion resistant qualities can be maintained on both the ID and OD. Also available in R-5, R-10, R-14 or as specified.

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Below are the basic configurations of our undeground duct.

Shape (see Figure 1)
Typical shapes for filament wound construction are round, rectangular and oval. Special shapes such as triangular are also available. Engineering assistance is available for designing projects requiring non-standard construction.

Figure 1
Typical Duct Shapes from Perry Fiberglass
(Custom shapes available upon request.)

Duct diameters are available from 2" - 144". Rectangular sizes are available as required for your projects. The same range of sizes are available in Perry 20S-IR7 pre-insulated double wall duct.

Wall Thickness
Duct wall thickness ranges from 1/8" to 1" (increasing in increments of 1/16"). Other wall thicknesses are available for abnormal burial depths or other special loading requirements. Standard ductwork is furnished with the following minimum wall thickness as set forth in PS 15-69 and SMACNA:

Diameter Wall Thickness
2" to 20" .125 inches
21" to 36" .187 inches
37" to 60" .250 inches

Standard length is 10'-0". Lengths up to 50 feet are available.

Fittings (see Figure 2)
Standard fittings include:

  • Elbows
  • Dampers
  • Tees
  • Register Boxes
  • Laterals
  • Square to Rounds
  • Y's
  • Crosses
  • Reducers
  • Flanges

Figure 2
Typical Duct Fittings from Perry Fiberglass
(Custom fittings available upon request.)

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Perry Fiberglass FRP duct is manufactured from high grade resins, filament wound over steel mandrels. This product meets the standards of UL 181, NFPA 90A and Uniform Mechanical Code (UMC) 10-1 for non-metallic ducts. Perry 20S Low Smoke™ duct is classified as a Class 1 air duct having a flame spread not over 25, and a smoke development rating not over 50. ASTM E84 (recognized by all as the most definitive of all fire test methods) tests were made by HPVA Laboratory and Testing Service, Reston, VA. HPVA is a recognized laboratory for the E84 fire rating test by the building code organizations under the Council of American Building Officials: Report No. Ner-TL329; ICBO; BOCA and SBCCI.

This summary is provided as an overview of the strict standards that Perry Fiberglass meets with the production of all our products. Complete technical specifications are available upon request for all Perry Fiberglass products.

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Perry Fiberglass FRP duct is easy to configure and install. Our ducts can be placed directly into a pea gravel backfilled trench without concrete encasement or tie downs in most cases.

Perry Fiberglass FRP duct can be cut with a saw or abrasive wheel without requiring specialized or expensive equipment. Joining methods are also easy and economical, resulting in significant savings in time and materials.

Basic underground installation of Perry Fiberglass FRP duct is quick, easy and economical.

Underslab installation (see Figure 3)
Generally, for underslab installation, the duct is simply laid on a 4" bed of pea gravel in a graded trench with good drainage. Encasement in concrete is not necessary. With sheet metal register boots in place and sealed, and then covered with pea gravel, the floor slab may be poured with no delay. Register Boots and Transitions may also be specified with FRP construction.

When installation is to be made where water infiltration is a threat, the duct can be manufactured with a resin rich veil on the OD. In this instance, the field joints would be made using the wet lay-up method. Please refer to installation instructions for your specific application for complete details.


Figure 3
Basic Underground Installation Method for Perry Fiberglass FRP duct
(Complete instructions available in the Download Area of our website.)

Depending on the end-use, Perry Fiberglass FRP duct can be joined using either "dry" or "wet lay-up" techniques.

Dry Method (see Figure 4)
Where applicable, a "dry" joint is easily achieved between duct lengths and/or duct and fittings. An internal galvanized coupling is sheet metal screwed and sealed into place. An extruded bead of non-hardening waterproof UL listed mastic (sealant) is applied to seal the joint. Finally, a wrap of Perry 6" wide polyethylene-backed pressure sensitive tape over the butted joint and screw heads provides a substantially tight system.

Figure 4
Dry Joining Method
(Complete instructions available in the Download Area of our website.)
*See Field Installation Guide for Details

Wet Lay-Up Method (see Figure 5)
For a more integrated joint, a "wet lay-up" bond is used where water infiltration is possible. This requires joining duct and/or fittings with resin and fiberglass matting to match the thickness of the duct being joined. This provides a strong watertight joint.


Figure 5
Wet Lay-Up Joining Method
(Complete instructions available in the Download Area of our website.)
*See Field Installation Guide for Details

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Our extensive library of data sheets and forms is now available in easy-to-use, printable PDF format.

Use our online form to submit your next RFQ. it's quick, easy and convenient.

Parallel branches in the same trench.

FRP duct work runs ready for pea gravel backfill.

Parallel FRP duct work runs. Consult factory for spacing requirements.

Field installation of large diameter factory subassemblies.

Unloading 40 ft. duct sections, nested for economical shipping.

FRP duct work capped and ready for leak testing.

Concrete encasement of parallel branches in close proximity.