MAN B&W L28/32H, Руководство пользователя

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08028-0D\H5250\94.08.12
It should be noted that no deduction can be made
due to background noise, and that the sound level,
measured in sound pressure, is approx. 3 dB(A)
higher than if measuring had been made in an
anechoic chamber.
Measuring of exhaust sound is done in the test hall,
directly after turbocharger, and with the exhaust pipe
dismantled.
Sound Measuring "on-site"
The Sound Power Level can be directly applied to
on-site conditions. It does not, however, necessarily
result in the same sound Pressure level as in the test
hall.
Normally the sound pressure is 3 dB(A) higher on-
site but it depends on the shape of the engine room.
Small rooms with hard non-absorbing walls with no
absorption give even higher values, while large
rooms with good absorption only result in minor
deviations.
The sound pressure level also depends on the
number of sound sources, and how close these are
placed.
The sound pressure level will e.g. increase by 3 dB
between two running engines if these are placed at
a distance of 2 metres from eachother, while the
sound pressure will increase by less than 1 dB if they
are placed at a distance of 5 meters.
Points of Measurement for GenSet
The distribution of points of measurement will, if
possible, be made according to the following stand-
ards:
a. CIMAC's Recommendation of measure-
ment for the overall noise of reciprocating
engines.
1970
b. DS/ISO 3744 Annex D 1982
Purpose
This should be seen as an easily comprehensible
sound analysis of MAN B&W Holeby GenSets. The-
se measurements can be used as tools in the project
phase as a reasonable basis for decisions concern-
ing damping and isolation in buildings, engine rooms
and around exhaust systems.
Measuring Equipment
All measurements have been made with Precision
Sound Level Meter according to standard IEC Pub-
lication 651, type 1 - with 1/1 or 1/3 octave filter
according to standard IEC Publication 225.
Definitions
Sound Pressure Level: L
P
= 20 x log dB
where p is the RMS value of sound pressure in
pascals, and p
0
is 20 mPa for measurement in air.
Sound Power Level : L
W
=10 x log dB
where P is RMS value of sound power in watts, and
p
0
is 1 pW.
Measuring Conditions
All measurements (where nothing else is mention-
ed) are made in MAN B&W Holeby's test hall with the
GenSet placed in an isolated position.
Room Volume V = 8000 m 3
Correction Factor K = 3 dB
Background Noise 65 - 70 dB(A)
During GenSet sound measurement, the exhaust
gas is led outside the test hall and through a silencer.
The GenSet is (if nothing else is stated) placed on a
resilient bed with generator and engine on a com-
mon base frame.
P
p
0
P
p
0
97.17
General
D 10 25 0 Description of Sound Measurements
1609510-3.3
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