in a free field. The designer should develop these
numbers based on the desired sound levels that
should exist at various locations after the
generator is installed. This information should be
based on the values used in the acoustical analysis
and verified by coordination with equipment
manufacturers during design. In some cases, a sound
attenuated enclosure may be needed to achieve the
desired result.
The designer should also indicate the desired sound
pressure levels that will be measured in the field.
The pressure levels should be based on the
acoustical analysis and should consider the
specified operating conditions of the diesel
generator operating in a free field, other
mechanical equipment, the building's sound
absorption characteristics, OSHA requirements, and
the building's functional requirements. The
location of the measurement points for the installed
diesel generator should be coordinated with the
SAFETY RUN TEST paragraph. Modify the radial
distance requirement from the engine, air-intake,
and exhaust to account for obstructions, variations
in site conditions, building configurations or
indicate points on the contract drawings at which
measurements are to be made.
**************************************************************************
The noise generated by the diesel generator set operating at 100 percent
load shall not exceed the following sound pressure levels in any of the
indicated frequencies when measured in a free field at a radial distance of
7 meters 22.9 feet at 45 degrees apart in all directions.
Frequency Band
Maximum Acceptable
(Hz)
Pressure Level
(Decibels)
31
[____]
63
[____]
125
[____]
250
[____]
500
[____]
1,000
[____]
2,000
[____]
4,000
[____]
8,000
[____]
The noise generated by the installed diesel generator set operating at 100
percent load shall not exceed the following sound pressure levels in any of
the indicated frequencies when measured at a distance of [22.9] [_____] m
[75] [_____] feet from the end of the exhaust and air intake piping
directly along the path of intake and discharge for horizontal piping; or
at a radius of [22.9] [10.7] [_____] m [75] [35] [_____] feet from the
engine at 45 degrees apart in all directions for vertical piping.
SECTION 16264A
Page 38
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