McGill AirFlow manufactures sturdy, low-cost Duct-D-Fuser terminal outlets for exposed HVAC air distribution systems in large, open-area commercial and industrial facilities. Products include a variation of grilles, fittings, assemblies, and registers.

The Model DDF-G Series Grilles are constructed to be flush mounted to curved or flat surfaces and designed to provide directional throw airflow performance characteristics similar to tap-mounted grilles.

The Type SP In-Duct Fittings and Assemblies are constructed of 360° perforated duct to provide low-throw, low-draft airflow performance.

Model DDF-R Series Registers are constructed of extruded aluminum and are available in deflection, slot, or drum register designs.

Because of their lighter weight, Duct-D-Fuser products are easier to install and less expensive to manufacture and ship than conventional rectangular tap-type diffusers. If local control of direction, volume, or velocity is required, refer to McGill AirFlow's Factair™ terminal outlet information.

Model DDF-GF grilles have a mitered, offset, galvanized sheet metal (optional paintable galvanized steel, 304 and 316 stainless steel, and aluminum) frame for easy installation on a round, flat oval, or rectangular duct assembly or fitting body using sheet metal screws.

The Model DDF-GOBD grille (not available in aluminum) incorporates an integrated, opposed blade damper for balancing volume flow rates among grilles.

There are 31 standard sizes. The Model DDF-GF grille can be field or factory installed. Factory-installed units incorporate closed cell foam gasketing for a dust-free seal.

Model DDF-G series assemblies use two or more factory-mounted grilles on a single run of spiral lockseam or longitudinal seam duct. Outlet opening sizes will vary along the length of the duct system. The selection of one standard Model DDF-GF framed grille size based on the largest opening size offers a uniform appearance. A more economical solution is to select standard Model DDF-G unframed grilles large enough to cover each individual opening. There is no maximum diameter except as that limited by manufacturing capabilities.

Model DDF-GB fittings incorporate an unframed DDF-G Series grille on a fitting body constructed from the appropriate SMACNA gauge material. The grille is sized to exactly fit the cutout required for the desired air volume. Model DDF-GB fittings are available in diameters ranging from 6 through 60 inches with 30° to 180° venting.

The Model DDF-GD fitting allows airflow modulation through the use of an internal barrel damper. Wing nuts mounted inside slots on either side of the grille provide accurate volume flow adjustments. The Model DDF-GD fitting incorporates unframed grilles only and is available in diameters ranging from 6 through 36 inches with 30° to 180° venting.

The Model DDF-SP in-duct fitting is built from 360° perforated, light-gauge, ribbed spiral lockseam duct with a 23 percent open area. Standard material construction is galvanized steel (paintable galvanized, cold-rolled steel, 304 and 316 stainless steels, and aluminum are available).

Model DDF-SP in-duct fittings are available in continuous lengths of 16 inches through 240 inches. Standard gauge-to-diameter relationships are 28 gauge for 9- through 42-inch diameters, and 26 gauge for 44- through 60-inch diameters. Model DDF-SP assemblies are outfitted with standard slip couplings for easy joining to adjacent duct sections.

The Model DDF-SP assembly is also built from 360° perforated, light-gauge, ribbed spiral lockseam duct with a 23 percent open area in gauges as noted for the in-duct fitting. The DDF-SP assembly ranges in length from 60- to 240-inches and incorporates appropriately sized orifice plates at predetermined locations along the assembly length for uniform airflow distribution. All DDF-SP assemblies must be designed using McGill AirFlow's Duct-D-Fuser design program.

System Design

Contact the McGill AirFlow sales engineering office or Duct Express™ outlet nearest you to request a free duct system design analysis of your next project.

McGill AirFlow's standard and universal Model DDF-R series deflection registers are constructed from extruded aluminum and finished in white (w) enamel or satin anodized (sa). The universal models are fabricated with a slight profile, which allows assembly to any duct curvature.

System Design

Contact the McGill AirFlow sales engineering office or Duct Express™ outlet nearest you to request a free duct system design analysis of your next project.

All models have gaskets on the margins for a dust-free, airtight seal. They are available in a minimum size of 3 inches by 10 inches to a maximum size of 12 inches by 36 inches (see table). They offer single (vertical) and double (vertical and horizontal) deflection, and are equipped with adjustable blades. The optional air scoop has face screw adjustment(s) for volume flow rate.

Model DDF-RLS linear slot registers are extruded from aluminum with a standard satin anodized finish. They can also be ordered with a white (w) enamel finish. And like the Model DDF-R deflection registers, they too have gaskets on their margins. The air scoop with face screw adjustments is standard on registers with 1-inch-wide slots but is not available on registers with 1/2- or 3/4-inch-wide slots.

They are available in lengths from 6 inches to 48 inches in 6-inch increments and can be used on 6-inch to 30-inch diameter duct. Model DDF-R linear slot registers offer three slot widths with up to 4 slots (see table).

These drum registers are ideal for exposed ductwork applications where long throws and adjustable air patterns are required. Typical installations include commercial kitchens and laundries, food-processing plants, manufacturing facilities, multi-purpose buildings, recreational centers, sports arenas, shopping malls, and warehouses.

The Model DDF-RD drum register is easily installed on the perimeter of round or flat oval spiral duct. The curved frame is rolled to the diameter of round duct or minor axis dimension of flat oval duct, insuring a perfect fit every time. This eliminates the need for costly saddle taps and will save you time and money during the installation process.

These drum registers are made of heavy gauge aluminum and are available in heights of 4, 6, and 8 inches and lengths up to 60 inches, which makes them versatile to any project.

To provide additional directional control of airflow, the drum register is able to rotate ±40 degrees up or down and the blades, spaced two inches apart, pivot side to side from the front fascia. This gives the drum register a clean architectural look to any exposed ductwork system.

Reference McGill AirFlow's Engineering Report No. 159 Type A DUCT-D-FUSER Grille Performance and Design Methodology for guidelines in designing exposed air distribution systems using this unique flush-mounted air diffuser for round, flat oval, and rectangular duct systems. This report gives detailed airflow and acoustical performance data as well as a product specification.

Also reference the performance data sheets for McGill's grilles and registers. Performance Data Sheets (.pdf)