Marine Installation Manual 2022-03 7-8
7 Engine Emissions
7.2 Engine noise
X62DF-S2.0
7.2.2 Exhaust noise
In the engine exhaust gas system, the sound pressure level at funnel top (see
Figure 7-6,  7-9) is related to:
• Distance of 1 m from edge of exhaust gas pipe opening (uptake)
• Angle of 30° to gas flow direction (see Figure 7-5)
• Average values Lp in dB, in comparison with ISO NR-Curves
• Overall average values LpA in dB(A)
• Without economiser, silencer, exhaust gas bypass
Each doubling of the distances from the centre of the duct reduces the noise level
by about 6 dB.
Figure 7-5 Exhaust noise reference point
Silencer after
economiser
Depending on the actual noise level allowed on the bridge wing — which is nor-
mally between 60 and 70 dB(A) — a simple flow silencer of the absorption type
may be placed after the economiser, if the noise reduction of the economiser is
not sufficient.
Silencer in exhaust line
A silencer in the main engine exhaust line may be considered, as on the X-DF en-
gines an exhaust gas bypass is installed by default.
Dimensioning
The silencers are to be dimensioned for a gas velocity of approx. 35 m/s with a
pressure loss of approx. 2 mbar at specified CMCR.
SM-0239
30°
1 m
reference
position
Funnel
r
2r: -6 dB
d: duct diameter
r: distance point to
sound source
d
To Next Page
Loading...
Need help?
General