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24
AST 14 C 152/00
CHP.7
FLUE GAS SYSTEM S
7.1 COAXIAL PIPES 100/60mm
TYPES: C12-C32-C42
The maximum acceptable length of horizontal coaxial pipes is 3 metres; in the presence of each additional
bend, maximum acceptable length must be reduced by 1 metre; furthermore, the duct must have a 1% slope
toward the exit, in order to avoid the entrance of rain.
The maximum acceptable length of vertical coaxial pipes is 4 metres; in the presence of each additional
bends, maximum acceptable length must be reduced by 1 metre.
DIAPHRAGMS
Model
Pipe length (m)
Flue gas discharge
diaphragm diameter (mm)
0,5 < L < 1
Ø 40
1 < L < 3
Ø 45
BTFS 24
3 < L < 4
No diaphragm required
0,5 < L < 3
Ø 42
BTFS 28
3 < L < 4
Ø 45
0,5 < L < 1
Ø 45
1 < L < 2
Ø 47
2 < L < 3
Ø 49
BTFS 32
3 < L < 4
No diaphragm required
For each additional bend decrease the max allowable length by 1 meter
7.2 SPLIT PIPES 80mm
TYPES: C12-C32-C42-C52-C82-B22
Air intake BTFS 24 E 28:
each 90° wide radius bend equals 1 m in length, each 90° narrow radius
bend equals 1.5 m in length, the load loss at the terminal is not to be
considered (with the exception of B22).
Discharge BTFS 24:
each 90° wide radius bend equals 1.5 m in length, each 90° narrow radius
bend equals 3,5 m in length.
Discharge BTFS 28:
each 90° wide radius bend equals 2 m in length, each 90° narrow radius
bend equals 4 m in length.
Air intake BTFS 32:
each 90° wide radius bend equals 1,5 m in length, each 90° narrow radius
bend equals 2 m in length, the load loss at the terminal is not to be
considered (with the exception of B22).
Discharge BTFS 32:
each 90° wide radius bend equals 2 m in length, each 90° narrow radius
bend equals 5 m in length.
The minimum length for the air intake pipe must be 1 metre (with the exception of B22 where there it is,
however, mandatory to have a minimum length for gas discharge of 0.5 metres). Install the air intake anti-
pulse terminal and the air deflector. Install the air intake diaphragm Ø 51 except on the model BTFS 32.
DIAPHRAGMS
C12-C32-C42-C52-C82
B22
Model
Pipe length (m)
Flue gas discharge
diaphragm (mm)
Pipe length (m)
Flue gas discharge
diaphragm (mm)
1 < L < 14
Ø 45
0,5 < L < 8
Ø 45
14 < L < 21
Ø 49
8 < L < 14
Ø 49
BTFS 24
21 < L < 28
No diaphragm
required
14 < L < 19
No diaphragm
required
1 < L < 11
Ø 49
0,5 < L < 9,5
Ø 49
BTFS 28
11 < L < 21
No diaphragm
required
9,5 < L < 15,5
No diaphragm
required
1 < L < 10
Ø 49
0,5 < L < 5,5
Ø 51
10 < L < 14
Ø 51
5,5 < L < 10,5
No diaphragm
required
BTFS 32
14 < L < 22
No diaphragm
required
