30
The equivalent lengths of special pieces, like curves
with various angles are shown in table 13.
The load losses of the external terminals can be
neglected because they are very low.
In the design phase it is necessary to verify that the
equivalent total length is less than or equal to the
maximum possible length as shown in figures 18÷28.
The maximum lengths of the air tube and the flue
pipe, according to the type of installation made, they
are shown in fig. 18 to fig. 27.
The aforementioned lengths are to be understood as
indicative, valid in the case of standard installations
in which the air tube and the flue pipe carry out a
linear path as shown in the respective figures.
Otherwise it is necessary to calculate the load loss
check (see CALCULATION EXAMPLE).
The following indications must be observed:
flue pipe length ≤ 1 m: install the flue pipe with a 2 or
3 cm slope against the generator.
Flue pipe length> 1.5 m: the condensation produced
by the exhaust pipe must be adequate collected and
drained by a special disposal system, in accordance
with the provisions of the UNI 11071 standard.
For a correct installation of the external combustion
products exhaust and combustion air intake terminals,
follow the instructions given.
As can be seen from table 13, for each special piece,
it is necessary to evaluate its equivalent length, which
in case of 45° curve is equal to 0.9 m.
Below is an example of a calculation related to a flue
outlet as shown in figure 17.
The maximum length of the pipe for air and fumes
provided for the model 35, type C13, is 20 m. It is
therefore possible to perform the installation.
If the total equivalent length was more than 20
meters, the path would have to be changed or pipes
Fig. 17
EXAMPLE OF FUME EXHAUST PIPE
with a larger diameter, 80 mm in diameter, that can
reach 40 m in length.
The total pressure drop of the pipe system is higher
to the maximum permissible load loss (219 Pa
GREATER of 200 Pa) then the installation IS NOT
PERMITTED.
7.4 CALCULATION EXAMPLE
Suppose we install a MEC MIX 35 with drain fume
and horizontal air intake pipe that develop as shown
in figure 17.
First linear section = 7 m.
90 ° curve = 0.9 m.
Linear section = 3 m.
45 ° curve = 0.5 m.
Linear section = 2 m.
45 ° curve = 0.5 m.
Line section = 2 m.
Total meters = 15.9 m.
Table 12
Natural Gas
GPL
35
82
52
45
96
67
DATA FOR THE CALCULATION OF THE AIR / FUMES SYSTEM WITH EXISTING TUBES IN COMMERCE
CO
2
in the fumes %
9,4-9,6
10,7
Mod.
Smoke temperature
output ° C
Flow rate
in mass kg/h
Table 13
curve 15°
curve 45°
curve 87°
Adapter
Coaxial
u.m.
m
m
m
m
35-45
0,5
0,9
1,1
3,2
Mod.
Equivalent length Ø 60
DATA FOR THE CALCULATION OF THE AIR / FUMES SYSTEM WITH Ø 60 OR Ø 80 CONDUITS SUPPLIED ON REQUEST
