Exhaust system
29
Velocity/Resistance curve at 400 °C
Bore v
elocity in m/s
Bore v
elocity in ft/s
Resistance in inches Wc
Resistance in mm Wc
For equivalent straight length see the table below:
Adding the pressure losses through the silencer to
the loss through the pipe work will give the total back-
pressure incurred by the exhaust system. This must
not exceed the figure quoted in the
Sales GuIde
Marine Propulsion Diesel Engines against the ap-
propriate engine and rating.
Pipe diameter
Bend 45 deg. Bend 90 deg.
(inches)
(m/bend)
(m/bend)
3.5
0.57
.33
4
0.65
.52
5
0.8
.90
6
0.98
2.28
7
.22
2.70
Backpressure - exhaust pipe - calculation
Using the value of the exhaust gas flow and having
calculated the backpressure for a certain silencer
(HD) you will be able to determine the resistance to
flow in a straight exhaust pipe.
The following formula is recommended:
where:
P = is backpressure through the exhaust pipe in Pa
L = is total equivalent length of straight pipe in me-
tres
Q = is exhaust gas flow in m
3
/s
D = is pipe diameter in metres
T = is exhaust gas temperature °C
NOTE! When the bends are used in the exhaust sys-
tem pressure loss is expressed in equivalent straight
length of pipe.
P = 6.32 x
x
L x Q²
D
5
(T + 273)
Summary of Contents for D11 series
Page 1: ...Marine Propulsion Diesel Engines Installation 1 1 D E D5 D16 series ...
Page 2: ......
Page 208: ...206 References to Service Bulletins Group No Date Concerns ...
Page 209: ...207 Notes ...
Page 210: ...208 Notes ...
Page 212: ...7748655 English 11 2007 ...