Exhaust System
AE Basics Brasil 2012
Daniel Kaiser
August, 2012
Exhaust System Course Objectives
Provide a Basic understanding of exhaust systems
Cover installations basics including design guidelines and
installation requirements as described in AEB 21.32
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Purpose of an Exhaust System
To carry all exhaust gasses from the engine and quietly
discharge them into the atmosphere while maintaining safety and
optimum engine performance.
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Exhaust Noise
Noise in often quantified as the sound pressure level and
expressed in decibels (dB), wich is a logarithm ratio of sound
pressure to a reference pressure.
A logarithm representation has been chosen, because it correlates
well with the hearing characteristics of the human ear.
The range of decibels in noise measurements is from 0 to about 140
from the smallest sound human ears can hear to the sound level
that will do immediate and permanent damage to the ear.
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For your reference, prolonged exposure to noise levels above
85dBA can cause permanent hearing damage
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Exhaust Noise
The human ear does not respond equally to all frequencies.
We are much more sensitive to sounds within the frequency range
of about 1-4 Hz than to very low or high frequency sounds.
For this reason, sounds meters are usually fitted with a filter whose
frequency response resembles the sensitivy of the human ear.
Sound pressure levels are expressed in three frequency-depending
weightings or scales – A, B, and C – among wich scale A is closest
to human hearing.
The A-weighted decibels are abbreviated as dB(A) or dBA.
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Exhaust Noise
Exposure to elevated noise levels can be a source of hearing loss.
Noise exposure has been also linked with cardiovascular effects,
and can be a source of annoyance, stress and sleep disturbance.
Due to these adverse health impacts, vehicle noise emissions are
limited by regulation in most countries.
Three major groups of standarts methods have been developed for
the measurement of noise from vehicles:
Sound level of moving vehicle
Sound level of stationary vehicle
Cabin noise level
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Exhaust Noise
Noise level regulations are a vehicle requirement, and not na engine
requirement.
The OEM is responsable for the vehicle noise compliance in the
location where the vehicle will be operating.
http://emissions.cummins.com/pem/content.jsp?siteId=1&langId=1033&menuId=4&overviewId=28&menuIndex=0
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Engine Noise
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Exhaust pressure test
-Back pressure limit is at Curve data sheet
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Exhaust pressure test
-Condictions test
The test needs to be done in the maximum
exhaust gas flow
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Exhaust pressure test
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