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PVS Installation Guide – Underground Ducts

4×1 PVS for Underground Duct Systems

Polyvinyl Duct (PVS)
Sheet Metal Connectors, Inc. PVS spiral pipe is formed from a coil of metal into a rigid PVC tube with a 4-ply spiral lockseam. It has smooth interior for low friction loss with the grooved seam entirely on the outside. This pipe has a resistance to crushing approximately 2 1/2 times that of longitudinal lockseam. Optional corrugations are available which increase the rigidity of the pipe by approximately 300%. Pipe sections can be joined together by an E-Z Flange with Barrel Clamp, E-Z Flange Jr. with Barrel Clamp, or Standard Spiral Pipe Connector.

Single-Wall Materials

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General
The use of PVS Ductwork eliminates the need for encasing in concrete. Because no additional concrete is required, savings can be considerable. By combining the strength of steel and the chemical inertness of plastic, PVS Ductwork is lightweight as well as corrosion and weather resistant. PVS ductwork will not rust, chip, crack, peel, corrode or produce odors. Although light in weight,PVS Ductwork is strong enough to walk on and will not collapse under concrete. PVS Ductwork is specified by more engineers and architects than any other underground HVAC duct system.

Durability
PVS ductwork is a rugged, durable material that will take ordinary shipping and handling without damage. PVS ductwork needs no protection in earth from sand, concrete or plaster. It is not affected by the minerals and salts found in normal backfilling materials. PVS ductwork has also passed thousands of accelerated salt spray and humidity cabinet tests with no loss of adhesion or corrosion resistance. It can be cut and formed with regular sheet metal equipment and tools with no harm to the coating. Even the largest diameter ducts are easily cut with portable metal-cutting saber saws or circular saws.

Connections

pvc-ezfjwbcE-Z Flange Jr. with Barrel Clamp – 6” to 24” Diameter
The E-Z flange jr. is a 5/8” flange turned out 90° on each end of the spiral pipe and fittings. The installer applies a gasket on one flange, mates the two flanges together, and attaches the barrel clamp. For field cuts a 5/8” flanged sleeve is available, cut the spiral pipe to the measured length and apply the sleeve.
*For dimensional data please refer to the E-Z Flange Specification Manual.

pvc-ezfwbcE-Z Flange with Barrel Clamp – 26” to 96” Diameter
The E-Z flange with barrel clamp can be factory installed or shipped loose for field installation. A set consists of two E-Z flanges and one barrel clamp. For field installation the installer attaches the E-Z flange to the pipe and fittings. Next the installer applies the gasket to one flange,mates the two flanges together and attaches the barrel clamp. SMC also installs E-Z flanges. Flanges are fastened and internally sealed on all ends of the spiral pipe and fittings.

*For dimensional data please refer to the E-Z Flange Specification Manual.


Standard Spiral Pipe Connector
pvc-sspcPipe to Pipe connections are made by using a fitting size coupling that slips inside the mating pipe sections, as shown. A stop bead runs around the middle of the coupling to center the coupling in the connection. Secure the connection by installing sheet metal screws through the outer shell of the duct, 1/2 inch from the stop bead.

c-pvc_seamsPVC Underground Fittings
Sheet Metal Connectors, Inc. PVC fittings and connections are fabricated in 1 x 4 or 4 x 4 material to protect against corrosion from soil. SMC PVC fittings are manufactured with an elbow lock seam or standing seam. SMC fabricates PVC fittings in most sizes and configurations using our state of the art equipment. All joints and connections should be sealed in accordance with SMC’s recommendations to assure an air tight system.
*The PVC fitting dimensional data listed in the PVC Specification Manual is for slip fit type connections only. For E-Z Flange PVC fitting dimensional data refer to the E-Z Flange Specification Manual.

All PVC fittings can be manufactured with:
E-Z Flange with Barrel Clamp – 26” to 96” Diameter
E-Z Flange Jr. with Barrel Clamp – 6” to 24” Diameter
Standard Spiral Slip Connector

Sealing
Spiral pipe and fitting slip connector joints must be sealed to prevent air leakage and to keep dirt and sand out of the duct system. PVC Tape is recommended as it is ideal for this usage. It has superior adhesive qualities, even in extremely hot or extremely cold weather. Also as an insurance factor, PVC Duct Sealer No. 8 is available. This is a flexible and self-curing air pressure sealant. This can be applied from one-gallon cans by brush application. It provides a positive sealing of joints and screw holes. PVC Duct Sealer No. 8 may also be obtained in a cartridge package. Approximate coverage is 375 linear feet per gallon at a 1/4” bead.
*PVC tape is not required for the PVC Spiral Pipe System.

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