UNI-COAT®—Duct and Fittings

Materials

UNI-COAT duct and fittings are made of galvanized steel (18 through 26 gauge) with a G-60 zinc coating. A 4-mil-thick (0.004 inch) coating of PVC plastic is heat sealed to both sides of the metal. The actual thickness may vary slightly due to coating tolerances. This 4 x 4 mil coating is used for underground HVAC systems as a corrosion-resistant barrier and for outdoor exposed HVAC systems to protect the metal from moisture and chemicals in the air.

Touch-Up Paint

Special attention should be given to any areas of the product in which the plastic coating is penetrated and the steel is exposed. That includes the edges of UNI-COAT duct and fittings, all penetrations (pop rivets, screws, etc.), and all areas of damage to the PVC plastic coating. UNI-COAT touch-up paint should be applied to cover all exposed metal.

Prepare the surface to be painted by cleaning it with soap and water. Then dry the surface thoroughly. When painting, provide adequate ventilation and use an OSHA-approved mask. A brush with soft bristles is recommended to apply paint. Thinning agents are not recommended; however, if a thinning agent is necessary, use a methylisobutyl ketone (MIBK). Methylethyl ketones (MEK) may be used, but they are extremely volatile.

Caution: PVC plastic touch-up paints are also available in aerosol cans. Aerosol paints contain large amounts of solvents to keep the paint in a liquid state and act as a propellant. These solvents can often attack the ductwork’s PVC plastic coating, causing the coating to delaminate from the metal duct. Brush-on paints also contain solvents, but in concentrations that are not as destructive.

© 2002-2008 McGill AirFlow LLC
An enterprise of United McGill Corporation—Family owned and operated since 1951

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