DuraVent DIS1 14 L36 BC Instructions Manual - Page 8

Browse online or download pdf Instructions Manual for Ventilation Hood DuraVent DIS1 14 L36 BC. DuraVent DIS1 14 L36 BC 16 pages. Positive pressure systems

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SECTION D-COMPONENTS

HIGH PRESSURE SYSTEM – up to 60" WC
THERMAL EXPANSION JOINT and ODD LENGTH
For Thermal Expansion we recommend using a Bellow Length (LB).
For ODD Length we recommend using a Variable Length (LV).
LOW PRESSURE SYSTEM – up to 6" WC
THERMAL EXPANSION and ODD LENGTH
For thermal Expansion and ODD Length we recommend using
an Adjustable Length (LA).

THERMAL EXPANSION

The inner pipe of Model DAS-PRO and DIS-PRO is load bearing and its thermal
expansion is the same as that of a continuous pipe. A simplified rule for exhaust
pipe expansion estimation is that the axial growth will be approx. 1" per 100' of
pipe length for each 100°F the flue gas temperature is above the surrounding air
temperature.
See Thermal Expansion Formula on page 3.
When assembled in any orientation, the amount of thermal expansion of the inner
pipe is directly dependent on the inner wall temperature and the length of pipe
between fixed points. Good installation practice requires that expansion greater
than 1/4 inch will be compensated for using a Bellows Joint or Adjustable Length,
depending on the maximum pressure encountered.
The flanged inner piping joints have negligible flexing capacity, and in addition, tees
and elbows are not designed to withstand bending moment forces. Because the
amount of outer casing axial movement is the same as inner casing movement, the
outer jackets of piping must slide to avoid excessive forces on Tees, Elbows of fixed
points. To accommodate outer casing movements, external guides along walls at
floors or in lateral breechings must allow for movement of pipe.
BELLOWS LENGTH
 
For exhaust pressure to 60 inches of water column, Bellows are recommended
for expansion and vibrational movements of the piping.
The Bellows has a 0.035" thick or heavier straight stainless steel liner to
protect the thinner spring material from heat and flow effects. It is used anywhere in
a system for axial and vibrational movements only and must be accurately
supported and guided. This part has limited lateral movement (1/8" max.) and
lateral offsets and parallel misalignments should be eliminated. The purpose of the
liner is to minimize contact, smooth flow, control erosion and eliminate resonance
caused by exhaust gases passing through the bellows. See Table 7 for Bellows
Properties
Typical Bellow design
 
7 
 
 
 
S
R
D
S
UBMITTAL 
ECORD FOR 
URA
TACK 
M&G
D
V
|
10
J
 
URA
ENT 
 
 
UPITER 
www.duravent.com 
 
ADJUSTABLE LENGTH (LA) - EXPANSION JOINT
The LA has two functions. It is used to compensate for thermal expansion and
make up odd lengths of vent..
It is shipped with graphite band assembly preassembled on the sliding inner pipe.
The LA is adjustable from 7 1/4 to 28 3/8 inch. See Figure 15
 
 
Gas Flow 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 15 – Adjustable Length (LA) 
 
 
Wrench – by 
 
others 
 
 
 
 
 
 
 
 
M
DCL,
DAS1,
DIS1,
DIS2
ODELS 
 
 
 
 AND 
L
|
A
,
N
Y
 
ANE 
 
LBANY
 
EW 
ORK
Cuttable half siding  
outer casing 
Moveable 
gasket 
assembly 
Cuttable sliding 
inner wall 
 
Spacing Tool 
supplied 
DIS4