Technical Note Noise emission from Dehumidifier Type C65E-11.1 Performed for COTES A/S Project no.: I101033 Page 1 of 10 01 July 2016 DELTA Venlighedsvej 4 2970 Hørsholm Denmark Tel. +45 72 19 40 00 Fax +45 72 19 40 01 www.delta.dk VAT No. 12275110 The report must not be reproduced, except in full, without the written approval of DELTA.
Page 2 of 10 Title Noise emission from Dehumidifier Type C65E-11.1 Journal no. Project no. Our ref. I101033 RUE/JEL/ilk Client COTES A/S Ndr. Ringgade 70c 4200 Slagelse Denmark Client ref. Rasmus Toftegaard Laboratory DELTA Agro Food Park 13 8200 Aarhus N Denmark Test conditions DS/EN ISO 11202:2010 DS/EN ISO 3744:2010 Results The dehumidifier type C65E-11.1 has been tested on 7 June 2016 and the sound pressure level was measured 1 metre from the dehumidifier in four positions. The maximum A-weighted sound pressure level, L pa at 1 metre distance was measured in position B (left side) at nominal flow mode: Standard deviation is σ tot = 1.6 db. Remarks 69.0 db re 20 µpa The results apply only to the object tested. Results are rounded to the nearest 0.5 db. DELTA, 1 July 2016 Rune Egedal Specialist, Acoustics Jens Elgaard Laursen Senior Specialist, Acoustics
Page 3 of 10 Contents 1. Introduction... 4 2. Test object... 4 2.1 Operating conditions during test... 5 3. Acoustic environment... 5 4. Measurement methods... 5 5. Sound pressure measurements and corrections... 6 6. Test results... 6 6.1 Sound pressure levels... 6 Annex 1 Measurement points... 8 Annex 2 Instrumentation... 9 Annex 3 Sound power levels for reference sound source B&K 4204... 10
Page 4 of 10 1. Introduction On behalf of COTES A/S, DELTA has performed sound measurements on a dehumidifier type C65E-11.1. The noise measurements were performed according to DS/EN ISO 11202:2010. 2. Test object Type: C65E-11.1 Make: COTES A/S Serial No.: 16.11018 Process Flow: 2600 m 3 /h Reg. Flow: 460 m 3 /h Power: 16.2 kw Dimensions: L: 820 mm / W: 1165 mm / H: 1615 mm Figure 1 Test set-up for the dehumidifier C65E-11.1. The front here is Position A (see Annex 1).
Page 5 of 10 2.1 Operating conditions during test The dehumidifier was tested operating at nominal flow mode. The noise emission was steady for the specified operating mode. 3. Acoustic environment The dehumidifier was placed indoor in a large workshop room at COTES, Rudolfgårdsvej 1A, 8260 Viby, Denmark (see Figure 1). On the ceiling of the workshop were mounted acoustic absorbing panels. The main dimensions of the room are 13.5 m 8 m 2.8 m (length width height). The acoustic quality of the test room was measured with a reference sound source from Brüel & Kjær type 4204. The measurements were performed by Rune Egedal, DELTA Acoustics, on 7 June 2016 and were performed according to ISO 3744 annex A2 in order to calculate the test rooms environmental correction factor K 2A. The results are listed in Table 1. 63 125 250 500 1000 2000 4000 K 2A [db re 20 µpa] 1.0 1.6 1.9 2.4 2.9 3.0 2.3 1.9 Table 1 Values of K 2A for the test room at COTES A/S, Viby J. 8000 The K 2A values are all lower than 7 db, and the test room therefore qualifies for sound pressure measurements according to DS/EN ISO 11202. The sound power level values of the reference sound source are enclosed in Annex 3. 4. Measurement methods The measurements were performed according to standard DS/EN ISO 11202. The sound pressure level was measured in four positions at 1 metre distance from the test object and at a height of 1.55 metre as illustrated in Annex 1. A photo of the measuring set-up is shown in Figure 1. The measurements of the test object were performed on 7 June 2016 by Rune Egedal, DELTA Acoustics. The used instruments are listed in Annex 2. All measurements were performed with the test object in nominal flow mode.
Page 6 of 10 5. Sound pressure measurements and corrections In each of the measurement positions the sound pressure level was measured for minimum 30 seconds. The background noise in the test room was measured while the dehumidifier was turned off. The measured time-averaged sound pressure levels L pa are corrected for each microphone position according to the following formula: Where L pa = L pa) - K 1A - K 3A. L pa is the energy A-weighted sound pressure level on the measuring surface, corrected for K 1A and K 3A. K 1A is the A-weighted correction for background noise level K 3A is an environmental correction depending of reflecting surroundings. The measurements were calculated and corrected in octave frequency bands 63-8000 before summing up. According to Annex A in DS/EN ISO 11202, the local environmental correction K 3A is dependent of the absorption area of the room surfaces: K 3A = 10 log (1 + 4S/A), where S is the area of a hemisphere with a radius of 1 metre: S = 2 π r 2 = 6.28 m 2. A is the total absorption area of the room: A = α S V, where α = 0.3 is an estimate of the mean absorption coefficient of the room surfaces. S V is the total area of the test room (walls, ceiling and floor), S V = 336 m 2. The value of K3A is determined to 1.0 db(a) 6. Test results 6.1 Sound pressure levels In Table 2 the measurement results are shown as the A-weighted sound pressure level in each of the four microphone positions: A-D (see illustration in Annex 1). C65E-11.1 Sound pressure levels, L pa in db re 20 µpa Measurement position A B C D Mean value Nominal flow mode 64.2 69.1 65.6 63.8 66.2 Table 2 Type C65E-11.1.Measured and corrected, averaged, A-weighted sound pressure levels L, pa in db re 20 µpa corrected for background noise (K 1A ) and the environment correction (K 3A ). The highest value was found in position B on the left side of the test object: 69.1 db(a).
Page 7 of 10 The background noise was measured in all four position positions. The average background noise was 32.0 db(a). The standard deviation of the measurements is σ R0 = 1.5 db (accuracy grade 2). The operating and mounting conditions are σ omc = 0.5 db and the total standard deviation is σ tot = 1.6 db. The expanded uncertainty U for a one-sided confidence level of 95% is U = 2.5 db. The corrected, averaged (four positions), A-weighted sound pressure levels per 1/1-octave frequency band are shown in Table 3. Condition Nominal flow mode 63 125 250 500 1000 2000 4000 8000 SUM 35.4 47.2 61.6 59.7 59.8 58.2 51.9 40.8 66.2 Table 3 Type C65E-11.1. Corrected, averaged, A-weighted sound pressure levels per 1/1-octave frequency band in db re 20 µpa.
Page 8 of 10 Annex 1 Measurement points The dashed lines show the measurement surface located at d = 1 metre from the reference box containing the test object. Four microphone positions were placed at height 1.55 m above the floor. B A C D Set-up for the sound pressure measurements (not in scale).
Page 9 of 10 Annex 2 Instrumentation Instruments and analysis software used for the sound measurements on 7 June 2016: No. Equipment Make Type Previous Calibration Next 02L019 Calibrator Brüel & Kjær 4231 6 Apr. 2016 Oct. 2016 06L059 ½ Microphone G.R.A.S 40AE 22 Jan. 2016 Jan. 2017 06L062 ½ Microphone G.R.A.S 40AE 30 Nov. 2015 Nov. 2016 06L057 ½ Microphone G.R.A.S 40AE 7 Apr. 2016 Apr. 2017 06L042 ½ Microphone G.R.A.S 40AE 21 Jan. 2016 Jan. 2017 09L031 Preamplifier G.R.A.S 26CA 8 Apr. 2016 Apr. 2018 09L043 Preamplifier G.R.A.S 26CA 21 Nov. 2014 Nov. 2016 09L042 Preamplifier G.R.A.S 26CA 21 Nov. 2014 Nov. 2016 09L039 Preamplifier G.R.A.S 26CA 21 Nov. 2014 Nov. 2016 04L008 Ref. Sound Source Brüel & Kjær 4204 23 Apr. 2015 Apr. 2018 14L002 Data aq. card National instruments NI9233 3 Dec. 2014 Dec. 2016 - Multimeter Fluke 179 - - For recording and analysis the program noiselab 3.0 and noiselab Batch Processor 3.1.1.4 from DELTA was used. The measurement set-up was calibrated before and after the measurements. All instruments are calibrated regularly in accordance with our DANAK guidelines.
Annex 3 Sound power levels for reference sound source B&K 4204 Page 10 of 10