Oval Double Wall Duct

Monroe Metal can produce a complete line of acoustically lined (double wall) flat oval duct and fittings. Pipe is fabricated with a solid outer shell, a layer of fire resistant fiberglass insulation, and an inner shell of perforated metal. This perforation reduces noise. The inner shell can, upon request, be fabricated with a solid inner shell for use where noise is not a problem. Fittings are constructed with a solid outer shell and a solid inner shell.

Advantages of a Lined Oval Duct:
• Provides a product for restricted space locations
• Provides a machine formed product designed to parallel round in characteristics
• Lined duct reduces fan noise
• Provides positive vapor barrier
• Lower friction loss
• Lined duct eliminates additional time and labor cost for field insulating

Standard Flat Oval Spiral:
• High and medium pressure application
• Available in 12’ maximum lengths or cut to length upon request

Monroe “v-Rib” Spiral:
• Low pressure application
• Lighter gauge material with 5 reinforcing ribs for extra rigidity
• Same quality and characteristics as standard oval
• Available in 12’ maximum lengths or cut to length upon request
• Lighter weight means easier handling and less field cost
• Due to its unique ribbed construction, it can also be used in medium pressure applications.

The fiberglass insulation meets the requirements set forth in NFPA pamphlet #90A (catalog MFPA #255) as to flame spread and smoke developed ratings. The K-value of the insulation at 75º MT = .260 BTU.

We offer fabrication in a wide range of materials, including paint grip, stainless steel and aluminum.

Products & Accessories

Accessory Fittings

To complete your job, we also offer a complete line of accessory fittings. These can be factory installed or shipped loose for field installation.

• Access Doors
• Angle Rings
• Insulation Stops
• Grille/Register Taps to fit double wall duct
• Rectangular to Oval
• Saddle Taps

Saddle taps can be lined or unlined and fabricated to fit major or minor axls.

No other manufacturer can offer such a complete line of accessories!


Duct Construction Standards
Double Wall Flat Oval Spiral- High Pressure, 1985 SMACNA
Pipe:       Major Width 
Outer Shell
 Gauge Major Width 
Inner Perf Shell
Gauge
 to 24"24  to 22"26
 25" - 48"22  23" - 44"24
 49" - 70"20  45" - up22
 71" - up18   

Fittings: Major Width 
Outer Shell
 Gauge Major Width 
Inner Solid Shell
Gauge
 to 36" 20  to 36"24
 37" - 60" 18  37" - up22
 61" - up 16  

* Fittings will be continuously welded with seams painted to prevent corrosion.




Double Wall Flat Oval Spiral- Low pressure/ Monroe "V-Rib"
Pipe:       Major Width 
Outer Shell
 Gauge Major Width 
Inner Perf Shell
Gauge
 to 24" 24  to 22"26
 25" - 48" 24  23" - 44"24
 49" - 70" 22  45" - up22
 71" - up 20   

Fittings:   Major Width 
Outer Shell
 Gauge Major Width 
Inner Solid Shell
Gauge
 to 36" 22  to 36"24
 37" - 60" 20  38" - up22
 61" - up 18  

* Fittings will be spot welded and sealed
** Spiral pipe is constructed of galvanized metal, meeting ASTM A-527 with a four-ply lockseam
** Other material and gauges available upon request
** Pipe available in 12’ maximum lengths or cut to length

Fiberglass insulation meets the requirements set forth in NFPA pamphlet #90A as to flame spread and smoke developed rating. The K-value is 75º MT = .260 BTU