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Rectangular Steel Products
All rectangular duct and fittings are fabricated from hot-dipped galvanized steel in gauges that meet or exceed SMACNA standards for rectangular ducts for the appropriate connection types listed.

For Low Pressure (Residential or Light Commercial) projects, these shop standards, which correspond closely with SMACNA guidelines for 1" W.G., are listed in the chart below, along with the standard connection types. Selections of alternate gauges (lighter or heavier) or alternate connection types are welcomed but at the sole discretion of the installer, who is considered knowledgeable whether those decisions are applicable for the project.

Largest Duct Dimension
Minimum Gauge
Minimum Connection
6" to 24"
26 Ga
Slip / Drive
26" to 30"
26 Ga
Stand Slip / Drive
32" to 50"
24 Ga
Stand Slip / Drive
50" to 72"
22 Ga
H-Flange Connector

For larger commercial projects, Shade Tree Mfg. is ready and able to produce items in accordance with any special local or engineering criteria regarding gauges and connector types. To properly process these orders, the customer shall supply information on the requirements. For projects requiring a certain SMACNA pressure class contruction, this information must be specified.
Dimensioning
When ordering, please note that unless specified, the following dimension practices are followed.

All opening dimensions are Outside Dimensions, with up-sizing of duct for insulation presumed taken care of by the installer.

All Lengths are overall lengths, as opposed to end of the drive.

For practices that are different (Drive to Drive), make sure to identify the difference.
Connector Types
When ordering, please specify connection types desired, including which duct dimension would receive drives.

Duct Raw (All S-Lock)
Plenum Raw (1/2" Notch)
Flange Out (Specify Size)
Flange In (Specify Size)
Double Fold / Hemmed Flange / Plenum Flange Out (5/8" Standard)
T-Lock / Dovetail (5/8" Flange Standard) for Sheet Metal or Fiberboard
IK-Lock (1/2" Internal Flange Standard) for Sheet Metal or Fiberboard
TDC / TDF / Ductmate-type Slide on Frame
Straight Duct / Drop / Plenum
Also termed as:

R / R2L / D / DS

Shade Tree Standards as Follows:

Straight Duct: Made 2 piece L-Shape Knocked Down, Snaplock Seam (4 piece Depending on Size – Pittsburgh Seam on request)

Straight Drops: Made 4 piece Knocked Down, with Flange one end

Plenums: Made 4 piece Raw to Sunkcap, Knocked Down
Horizontal Elbows
Also termed as:

CET / CETL / CE / CER / RE / E
Sweep Elbow
Cut 7 Elbow
Flat Elbow
Long Way Elbow
Hard Way Elbow
Angle (45° Elbow)

Shade Tree Standards as Follows:

(Unlined) = Radius Back, Square Throat, 2" Throat Legs, No Turn Vanes
(Lined) = Radius Back, Square Throat, 3" Throat Legs, No Turn Vanes

Specify Square Back With Square Throat, Radius Back with Radius Throat, Square Back with Radius Throat, Radius Back with Square Throat
Specify Change Symmetry If A Drop Cheek Elbow is Required

SMACNA Standard (As Reference) is Radius Back, Radius Throat, with Centerline Radius 1.5 times Duct Dimension; Turn Vanes if Square Throat
Vertical Elbows
Also termed as:

CET / CETL / CE / CER / RE / E
Regular Elbow
Cut 5 Elbow
Flat Elbow
Short Way Elbow
Easy Way Elbow
Angle (45° Elbow)

Shade Tree Standards as Follows:

(Unlined) = Radius Back, Square Throat, 2" Throat Legs, No Turn Vanes
(Lined) = Radius Back, Square Throat, 3" Throat Legs, No Turn Vanes

Specify Square Back With Square Throat, Radius Back with Radius Throat, Square Back with Radius Throat, Radius Back with Square Throat
Specify Change Symmetry If A Drop Cheek Elbow is Required

SMACNA Standard (As Reference) is Radius Back, Radius Throat, with Centerline Radius 1.5 times Duct Dimension; Turn Vanes if Square Throat
Transitions
Also termed as:

RS / RSL
Reducer
Duct Reducer
Tapered Duct Reducer

Shade Tree Standards as Follows:

Straight on Left
Flat on Top
Length = Twice (Change+Set+Rise), minimum 12" Long
Take Offs
Also termed as:

Shoe Tap
Straight Take Off
Starting Collar
Take Off Riser
Plenum Riser
Plenum Starter
Rising Plenum Starter

Shade Tree Standards as Follows:

Shoe Tap: 7" Long with 45° Shoe, T-Lock Connection
Straight Take Off: 4" Long, T-Lock Connection
Plenum Take Off: 12" Long; 3" Rise; Center Flare; T-Lock Connection
Goldberg Fitting
Also termed as:

Parker
Airplane
Reverse
Bull Nose

Shade Tree Standards as Follows:

Center Flare with 3" Bottom Throat

For Straight on Left, Straight on Right, or any other, include a drawing to ensure accuracy.
Square to Round / Oval
Specify Width, Depth, And Diameter When Ordering

When Not Concentric, Supply Sketch

Shade Tree Standards As Follows:

Centerflare Both Directions
Male Slip Fit On Round End
Offset / Upset
Offset
Offset - Straight Heel
Riser / Upset
Shade Tree Standards as Follows:

Single Dimension Offset / Upset Made With Curved Heels Unless Length Prohibits

Double Dimension Offset / Upset (i.e. Offset with Upset) Made With Straight Heels

Transitioning Offst / Upset Made With Curved Heel At Shade Tree Discretion

Supply A Sketch For Greates Accuracy When Multiple Changes Occur In A Single Fitting
Miscellaneous
Specialty Fittings and Connectors Can Be Fabricated Request

For Flexible Connectors, Goosenecks, Bird Screens, Filter Racks, Grease Duct, Or Any Other Of A Variety Of Specialty Items, Feel Free To Contact Us.
Double Wall Rectangular Duct

Specifications