UNI-STACK™-1400 Series
Double-Wall Ductwork

UNI-STACK-1400 double-wall ductwork is designed for positive and negative pressure chimney and breeching systems that vent boilers, kilns, incinerators, grease ducts, and emergency generators. The double-wall design features a stainless steel inner liner and aluminized steel outer shell. It helps maintain a high flue gas temperature so that corrosive gases will not condense inside the stack. Insulation is available to lower the temperature of the duct’s outer shell. This duct can be used with fuels such as liquid propane gas, natural gas, #2, #4*, #5*, and #6* fuel oils, wood*, and coal* (*316 stainless steel should be specified when using these fuels for combustion). It is suitable for caustic air and fumes, grease vapors, and particle-containment systems. UNI-STACK-1400 ductwork can handle flue gas with a maximum temperature range of 1,000°F to 1,400°F for continuous firing and a maximum temperature range of 1,400°F to 1,800°F (2,000°F in grease duct applications) for intermittent firing.

Construction

UNI-STACK-1400 duct is constructed with a welded longitudinal seam in lengths of 18, 30, and 42 inches. Standard diameters are 6 to 48 inches in 2-inch increments. For diameters of 6 to 36 inches, the standard material is 20-gauge, 304 stainless steel for the liner and 24-gauge aluminized steel for the outer shell. For diameters of 38 to 48 inches, the standard material is 18-gauge, 304 stainless steel for the liner and 20-gauge aluminized steel for the outer shell. The duct is also available in other diameters and with 316 stainless steel liners or outer shells. Liners have van-stoned ends. Vee bands and sealant are provided to secure the flanged connection. Outer shells are joined by draw bands for environmental protection. To maintain the concentric spacing between the inner liner and outer shell, spacer clips are welded to the liner and hooked over the edges of the shell.

Clearance Requirements

For noncombustible materials, Model 1400 (1,000°F applications) requires a clearance of 2 inches when inside diameters are 18 inches or less, and a clearance of 4 inches when inside diameters are greater than 18 inches. For Model 1400 (1,400°F applications), the clearance is the same as for combustible materials. For Models 1401, 2, 3, 4 (1,400°F applications), a clearance of 4 inches from noncombustible materials is required when the inside diameter is 18 inches or greater.

The following clearances must be maintained from combustible building materials.

Model 1400:
4 inches for 1,000°F applications, 6 inches for 1,400°F applications.

Models 1401, 2, 3, 4:
2 inches for 1,000°F applications, 4 inches for 1,400°F applications.

Models 1400, 1, 2, 3, 4 (grease duct applications):

Application References and Listings: UL, ULC, NFPA

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

Unless otherwise noted, all (™) trademarks and (®) registered trademarks are property of United McGill Corporation.