Appendix
Si39-406
100
General Information
7.1.2 Faint Noises and Correcting Operating Noise with Respect to Faint
Noises
Faint noises are defined as peripheral sounds existing while the unit is not running, which are
picked up when measuring operating noise. If these faint noises are 10 dB or more than the noise
produced by the unit, the measured value can be taken as the operating noise of the unit. But, the
difference must be corrected if less than 10 dB, because of the effect these noises have on the
actual measured value. Also, when the sound meter remains unchanged even while the unit is
stopped, we can determine the operational noise to be at least 10 dB less than the faint noises, but
we cannot pinpoint the operating noise exactly.
For example, if the faint noises are some 65 dB and the noise produced by the unit in operation is 70 dB, the
indicated difference comes to 5 dB. Using Table 3, we recommend you correct the operating noise by about 2
dB to 68 dB.
7.1.3 Calculating Operating Noise
When two or more units are running at the same time, the amount of operating noise they produce
rises. The total amount of noise produced can be obtained ahead of time with Chart 4.
Sample calculation 1
L
1
and L
2
are given as compounded sounds of 50 and 49 dB respectively.
Since L
1
– L
2
= 50 – 49 = 1, the corrective value is 2.5, therefore 50 + 2.5 = 52.5 dB.
Sample calculation 2
When sounds of 40 dB, 38 dB, 37 dB and 40 dB are placed in order of magnitude, we obtain the
following:
40 dB, 40 dB, 38 dB, 37 dB
To start, the difference between 40 dB and 40 dB is 0, therefore we take a corrective value of 3dB and
obtain 40 + 3 = 43 dB. The compounded sound of 43 dB and 38 dB has a 5.0 dB difference, thus a
corrective value of 1.2 dB, which gives us 44.2 dB from 43 + 1.2. In the same manner, the corrective
value for 44.2 dB and 37 dB is approximately 0.7 dB, or in other words, 44.2 + 0.7 = 44.9 dB.
Table 3 Correcting the effect of faint noises
Unit: dB
Difference between when noise
is produced and when not
1
2
3
4
5
6
7
8
9
10
Corrective Value
–6.9
–4.4
–3.0
–2.3
–1.7
–1.25
–0.95
–0.75
–0.60
–0.45
Summary of Contents for REYQ96MTJU
Page 1: ...Design Installation Testing Instruction R410A Heat Recovery 60Hz REYQ96MTJU Si39 406...
Page 6: ...Si39 406 iv Table of Contents...
Page 34: ...Installation Si39 406 28 General Information Flaring Procedure...
Page 68: ...Installation Si39 406 62 General Information Caution Caution label 3P124617 4P124614...
Page 114: ...Appendix Si39 406 108 General Information 3P135887 1...
Page 126: ...Appendix Si39 406 120 General Information 7 8 3 BS Unit BSVQ36MVJ BSVQ60MVJ 4D045338...
Page 128: ...Appendix Si39 406 122 General Information 7 9 2 Field Wiring REYQ96MTJU 3D042647A...
Page 156: ...Refrigerant Piping Si39 406 150 Installation Manual REYQ96MTJU...
Page 158: ...Refrigerant Piping Si39 406 152 Installation Manual REYQ96MTJU...
Page 230: ...Precautions for New Refrigerant R410A Si39 406 224 Precautions for New Refrigerant R410...
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