16 ALR 110F – 150F Product Manual ALR2-3
Sound Data
Table 7, ALR 110F - 150F, Sound Pressure
Octave Band Sound Pressure Levels Per ARI Standard 370 (dB)
ALR
Unit Size
63 hz 125 hz 250 hz 500 hz 1000 hz 2000 hz 4000 hz 8000 hz
Overall "A"
Weighted
110 65 68 69 66 62 60 57 53 68.5
120
65 68 69 66 62 60 57 53 68.5
130
66 69 70 67 63 61 58 54 69.5
135
66 69 70 67 63 61 58 54 69.5
140
67 70 71 68 63 61 59 54 70.0
145
67 70 71 68 63 61 59 54 70.0
150
68 71 72 69 64 62 59 55 71.0
NOTES
1. Based on Uniform Spherical Radiation, Q=1
2. Sound pressure at 30 feet from unit.
Table 8, ALR 110F - 150F, Sound Power
Octave Band Sound Power Levels Per ARI Standard 370 (dB)
ALR
Unit Size
63 hz 125 hz 250 hz 500 hz 1000 hz 2000 hz 4000 hz 8000 hz
Overall "A"
Weighted
110 95 98 99 96 92 90 87 83 98.5
120
95 98 99 96 92 90 87 83 98.5
130
96 99 100 97 93 91 89 84 99.5
135
96 99 100 97 93 91 89 84 99.5
140
97 100 101 98 93 91 89 84 100.0
145
97 100 101 98 93 91 89 84 100.0
150
98 101 102 99 94 92 89 85 101.0
Per ARI 370 - Sound Rating of Large Outdoor Refrigerating and Air-Conditioning Equipment
Sound levels can be as important as unit cost and efficiency, and must be addressed before the start
of any development program. Efforts by McQuay Design Engineers to design chillers that are
sensitive to the sound requirements of the market have paid off.
Background Information
Sound is a vibration in an elastic medium and is essentially a pressure and particle displacement
phenomena. A vibrating body produces compression waves and as the waves are emitted from the
vibrating body, molecules are ultimately compressed. These waves are transmitted through gases,
liquids, or solids-anything that is elastic or viscous.
The sound data provided in this section is presented with both sound pressure (Q=1 and 30 feet from
unit) and sound power levels. Sound power is the total sound energy radiated by a source per unit of
time integrated over the surface through which the sound is radiated. Sound power is a calculated
quantity and cannot be measured directly like sound pressure. Sound power is not dependent on the
surrounding environment or distance from the source, as is sound pressure.
Sound pressure varies with the distance from the source and is dependent on its surroundings. For
example, a brick wall located 10 feet from a unit will affect the sound pressure measurements differently
than a brick wall at 20 feet. Sound pressure is measured in decibels (dB), which is a dimensionless
ratio (on a logarithmic scale) between measured sound pressure and a reference sound pressure level.
Sound Pressure Levels - Full Load
Sound pressure tables give the overall "A" weighted sound pressure levels which are considered
typical of what may be measured in a free field with a hand held sound meter, in the absence of any
nearby reflective surfaces. The sound pressure levels (Table 7) are measured at 30 feet from the side
of the unit at 100% unit load, no reflecting walls Q=1, and ARI conditions, 95°F (35°C) ambient air
temperature and 54/44°F (12/7°C) evaporator water temperatures for air-cooled units.
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