Greenheck Fan OSSFD-XXX Series Manuale Utente

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Breakaway Connections
Proprietary Flange System Breakaway Connections 
(TDC by Lockformer, TDF by Engle)
TDC and TDF systems are 
approved as breakaway 
connections when installed as 
described in the TDC or TDF 
addendum to the SMACNA Duct 
Construction Standards except 
the corners may not be bolted. 
Standard 6 in. (152mm) metal 
clip may be used with spacing as shown in Figure 8. 3/8 
in. (9.5mm) metal bolts and nuts may be used to fasten 
together corner pieces (see Fig. 9). 
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Figure 8:  Detail of proprietary flanged system 
breakaway connections.
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Traditional Breakaway Style Transverse Joints
Transverse joints illustrated at right have always been 
approved as breakaway connections. SMACNA testing 
has also approved the following variations as breakaway 
connections.
 
•  The breakaway connections shown (Fig. 6) can 
be applied with maximum of two #10 (19mm) 
sheet metal screws on each side and on the 
bottom located in the center of the slip pocket and 
penetrating both sides of the slip pocket. 
 
•  Transverse joints illustrated 
can be applied as top and 
bottom joints with Drive Slip 
- side joints in duct heights 
up to 20 inches (508mm) 
See Fig. 5.
Round and Oval Duct Breakaway Connections
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Fig. 5
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Fig. 6
Round or flat oval ducts connected to Type R or O damper 
collars shall be attached with #10 (19mm) sheet metal 
screws as follows:
 
•  Ducts to 22 in. (558mm) wide (or dia.) and smaller 
shall have three screws.
 
•  Ducts larger than 22 in. (558mm) wide (or dia.) up to 
and including 36 in. (914mm) wide (or dia.) shall have 
five screws.
NOTE:  All breakaway connections described may have duct 
sealant applied, PA2084T duct sealant adhesive 
manufactured by Precision, DP1010 water base duct 
sealant manufactured by Design Polymetrics, or Grey 
Pookie in accordance with SMACNA recommendations.
Manufactured Flanged System Breakaway 
Connections
Flanged connection systems manufactured by Ductmate, 
Ward, and Nexus are approved as breakaway connections 
when installed as illustrated (Fig. 7). 
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Fig. 7
Duct End
Flange
Corner Piece
3/8 in. bolt 
(optional)
Fig. 9