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Natural Science Forum / Physics / Acoustics / June 2005Sound data for cooling units on refrigerated trailers
Hello, It's related to a parking project for trucks / vans along a high way. I got to calculate whether noise from cooling units on refrigerated trailers would be a problem for the houses nearby when the parking will be built. I know that those units make a lot of noise, but have no sound data. I called to Carrier here in Norway but it was like asking for the moon. No feed back after 2 weeks. Does anyone have some useable sound datas for those units? octav band would be best, but total level in dBA would do. Thank you in advance for any help! Alain Bradette > It's related to a parking project for trucks / vans along a high way. I > got to calculate whether noise from cooling units on refrigerated [quoted text clipped - 5 lines] > for those units? octav band would be best, but total level in dBA would > do. Below is a 1992 spectrum I took at 17 paces (43ft, 13m) from a line of 17 refrigeration trucks parked at 22:20hr at a load/unload dock by a food factory: (I chose the measurements position to be where the sound radiation was maximum; looking directly at the load/unload platform with the refr. trucks in front of that dock, backed into that dock.) These were taken in 1992, 13 years ago, and most units were noisy then. There have been some improvements in refrigeration unit design. The compressor/condenser units that are mounted in the trailer fronts, high are noisiest. Some are mounted under the trailer between the wheels, where noise emission to the community is less. These 1992 units were mostly trailer-front. Other data from that project indicate that at a distance of 5ft (1.5m+-) from a single trailer, I found the noise level level to be 88 dBA at full power, and 86 dBA at idle with major sound frequencies of 50Hz and 160 through 2,000 Hz. ///////////1/3 octave band data; meter microphone located 5' above a hard asphalt parking lot, as was also the refr. trailer.\\\\\\\\\\\\\\\\\\\\\\\ "date stamp =","20 JUL 92 22:20:19" "note =","IN TRAILER PARKNG COURTYARD. 17 REFRS INA LINE @17 PACES(43FT) " "Frequency","Channel 1" "8 6.30 Hz", 71.0 "9 8.00 Hz", 65.1 "10 10.0 Hz", 70.7 "11 12.5 Hz", 67.3 "12 16.0 Hz", 56.5 "13 20.0 Hz", 58.7 "14 25.0 Hz", 59.8 "15 31.5 Hz", 57.8 "16 40.0 Hz", 59.2 "17 50.0 Hz", 79.3 "18 63.0 Hz", 83.7 "19 80.0 Hz", 89.3 "20 100 Hz", 79.1 "21 125 Hz", 78.9 "22 160 Hz", 82.3 "23 200 Hz", 74.3 "24 250 Hz", 75.3 "25 315 Hz", 77.1 "26 400 Hz", 81.5 "27 500 Hz", 73.2 "28 630 Hz", 72.2 "29 800 Hz", 68.5 "30 1.00kHz", 69.9 "31 1.25kHz", 67.4 "32 1.60kHz", 69.6 "33 2.00kHz", 67.3 "34 2.50kHz", 65.5 "35 3.15kHz", 66.6 "36 4.00kHz", 63.6 "37 5.00kHz", 61.4 "38 6.30kHz", 60.2 "39 8.00kHz", 59.6 "40 10.0kHz", 57.0 The A-Level was either 80 or 84 dBA (calculate it yourself). The Linear level was 94 dB re 20 uPa. Angelo Campanella Thank you Angelo for you comprehensive answer. I do appreciate it. With some adjustments to my case, it will give good results. Alain Bradette excuse me for `butting in, but first you have to "rank order" the sources?Also you need to find the "sound power" output of same?to do that you'd need a meter, keeping it close to the ground to avoid reflections?And apply geometric spreading?What "criteria" would you apply at the property line? (I don't know much about criteria). yours Richard > Thank you Angelo for you comprehensive answer. I do appreciate it. With > some adjustments to my case, it will give good results. > > Alain Bradette where's this thread gone? richard > excuse me for `butting in, but first you have to "rank order" the > sources?Also you need to find the "sound power" output of same?to do that [quoted text clipped - 8 lines] >> >> Alain Bradette > where's this thread gone? > richard The thread itself hasn't gone anywhere; what's probably happened is that your news reader is only showing you threads from the last 30 or so days. Chris W  SignatureThe voice of ignorance speaks loud and long, But the words of the wise are quiet and few. --- |
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