MAN B&W 7.09
Page 6 of 7
MAN Diesel
MAN B&W ME-GI TII engines 198 86 39-0.2
Fig. 7.09.05: Allowable daily and occasional noise exposure zones
078 12 97-4.4.0a
Vent silencer
The vent silencer is needed because noise from
venting valves can be expected to be in the region
of 130 to 170 dB(A) Lw.
This description is made as a general specifica-
tion and guideline for design and/or purchase of
the vent silencer.
Operating conditions
Acoustic requirements
Sound pressure level at 5 m distance: .....110 dB(A)
A chart of the allowable daily and occasional
noise exposure zones is shown in Fig. 7.09.05.
Safety requirements
The vent silencer must comply with:
• Class requirements
• acoustic requirement in compliance with the
IMO noise limits for seafarers.
The silencer design must secure that no gas is
being trapped inside the silencer. Otherwise the
function of the HC detector in the return pipe
could be disturbed.
10 min
70
80
90
100
110
120
130
db (A)
1 2 4 8 16 24
Allowable daily and occasional noise exposure zones
Duration exposure
hours
No exposure
(Zone A)
Occasional exposure with
ear muffs and ear plugs
(Zone B)
Daily exposure
with ear muffs
(Zone D)
Daily exposure with
ear muffs and ear plugs
No protection required
(Zone E)
L
eg
(24) = 80
Occasional
exposure with
ear muffs or
ear plugs
(Zone C)
L
eg
(24) = 80
Medium Natural gas Ethane
Temperature, °C ÷55 to +55 ÷89 to +55
Pressure upstream, bar 300 600
Mass flow rate, kg/s See ‘Calculating the
venting gas flow’
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