Noise Control (Air Compressors) Regulations
(Enacting provision omitted—E.R. 4 of 2023)
[1 March 1992]
(Format changes—E.R. 4 of 2023)
These regulations may be cited as the Noise Control (Air Compressors) Regulations.
(Omitted as spent—E.R. 4 of 2023)
In these regulations, unless the context otherwise requires—
air compressor (空氣壓縮機) means any portable motor driven device capable of supplying compressed air at 500 kPa pressure or above which is designed or used for the purpose of carrying out any construction work; air flow (氣流) means nominal air delivering capacity of an air compressor; motor power (摩托功率), in relation to an air compressor, means the maximum power of the drive motor of the compressor; (L.N. 69 of 2023) noise emission label (噪音標籤) means a noise emission label issued by the Authority under regulation 8.Air compressors are hereby prescribed for the purposes of Part III of the Ordinance.
For the purposes of section 17(1) of the Ordinance, all air compressors shall comply with the prescribed noise emission standard for air compressors.
For the purposes of sections 14, 15 and 17 of the Ordinance, the prescribed noise emission standard for air compressors is set out in Schedule 1.
A noise emission label shall be in the form set out in Schedule 4.
For the purpose of section 17(1) of the Ordinance, every air compressor shall be fitted with a noise emission label issued in respect of that air compressor.
For the purposes of sections 14, 15, 16 and 17 of the Ordinance, the test conditions for air compressors are the conditions set out in Schedule 2.
An application for a noise emission label shall be made to the Authority in the prescribed form set out in Schedule 3 and shall be accompanied by an application fee of $530 for each noise emission label applied for. (L.N. 260 of 1994; L.N. 497 of 1996; L.N. 582 of 1997; L.N. 308 of 2000; L.N. 184 of 2005; L.N. 101 of 2008; L.N. 43 of 2016)
On an application made in accordance with subregulation (1), the Authority must issue to the applicant any noise emission label applied for if the Authority is satisfied that—
either of the following conditions is met—
that a noise testing report certificated by a person specified in subregulation (2A) that the air compressor in respect of which the application was made complies with the standard set out in Schedule 1 when tested under the conditions set out in Schedule 2 has been issued;
that the air compressor in respect of which the application was made complies with a standard that is substantially the same as or more stringent than that set out in Schedule 1 when tested under conditions comparable to those set out in Schedule 2; and
an application fee of $530 for each noise emission label applied for has been paid. (L.N. 69 of 2023)
For the purposes of subregulation (2)(a)(i), the person is—
a corporate member of the Hong Kong Institute of Acoustics Limited;
a professional member of the Hong Kong Institute of Qualified Environmental Professionals Limited; or
a registered professional engineer (as defined by section 2(1) of the Engineers Registration Ordinance (Cap. 409)) in the building services, environmental or mechanical discipline. (L.N. 69 of 2023)
Not later than 28 days after an application made under subregulation (1) is received by the Authority, the Authority shall issue the noise emission label or labels applied for or serve on the applicant written notice of his refusal to issue the noise emission label or labels, and if at the end of those 28 days he has done neither of those things, a noise emission label or labels shall be deemed to have been issued.
No fee paid in respect of an application for a noise emission label shall be liable to be refunded.
This regulation has effect in relation to an act—
concerning an air compressor; and
falling within the descriptions of section 14(1), 15(1) or 17(1) or (2) of the Ordinance.
Subregulation (4) applies in relation to the act if it is committed before the transition date.
Subregulation (4) also applies in relation to the act even if it is committed on or after the transition date so long as a noise emission label was issued (or was deemed to have been issued) in respect of the air compressor before the transition date.
Schedule 1 as in force immediately before the transition date continues to have effect in relation to the act as if the amendment to that Schedule made by section 6 of the amending Regulation had not been made.
In this regulation—
amending Regulation (《修訂規例》) means the Noise Control (Air Compressors) (Amendment) Regulation 2023 (L.N. 69 of 2023); (E.R. 4 of 2024) transition date (轉標準日) means the date on which section 6 of the amending Regulation comes into operation .| Column 1 | Column 2 |
| Motor power of air compressor in kW (“P”) | Maximum permissible sound power level in dB(A) |
| 15 or below | 97 |
| Over 15 but below 350 | 95 + 2 log P(1) |
| 350 or above | 102 |
(Schedule 1 replaced L.N. 69 of 2023)
The purpose of this test is to determine the noise emitted by air compressors.
Both measured and calculated values obtained by this test constitute the basic data for checking that the noise emission of air compressors complies with the prescribed standard.
This test is applicable to portable air compressors (hereinafter referred to as appliances). The test specifies the procedures for use in determining the sound power level of such appliances for the purpose of testing as to conformity under the Noise Control (Air Compressors) Regulations (Cap. 400 sub. leg. C).
Sound pressure level LpA
The sound pressure level LpA is obtained by applying the weighting A to the sound pressure level Lp.
The sound pressure level Lp, expressed in dB, of a noise is defined by—
| Lp = | 20 log10 | P | ||
| Po |
Where—
P is the effective sound pressure value measured at a particular point, expressed in Pa;
Po is the effective reference sound pressure, equal to 20 × 10-6 Pa.
The value LpA of the A-weighted sound pressure level, expressed in dB(A), is obtained by applying the weighting A to the measuring system.
Measuring surface
The measuring surface of area S (see paragraph 8.3) is a hypothetical surface surrounding the sound source and on which the measuring points are arranged (see paragraph 6.3).
Surface sound pressure level LpAm
The surface sound pressure level LpAm is the root mean square of the sound pressures recorded on the measuring surface, calculated in accordance with the method set out in paragraph 8.4.
Sound power level LWA
The sound power level LWA is obtained by applying the weighting A to the sound power level LW.
The sound power level LW, expressed in dB, of a sound source is defined by—
| LW | = | 10 log10 | W | ||
| Wo |
Where—
W is the total sound power generated by the sound source, expressed in watts;
Wo is the reference sound power, equal to 10-12W.
The value LWA of the A-weighted sound power level, expressed in dB, is obtained by applying the weighting A to the measuring system.
Extraneous noise
Extraneous noise means the noise resulting from background noise and parasitic noise.
Background noise
Background noise means any noise recorded at the measuring points which is not generated by the appliance.
Parasitic noise
Parasitic noise means any noise at the measuring points which is generated by the appliance but not directly radiated by it.
Acoustic criterion for the environment
The acoustic criterion for the environment of the appliances is their sound power level.
General
The instruments shall be designed to measure the A-weighted level of the root mean square of the sound pressure. The level of the root mean square value in time for a measurement point is obtained either by direct reading of the instrument, or by calculation in accordance with paragraph 11.
Measuring instruments
The following instruments may be used—
a sound level meter meeting the requirements of International Electrotechnical Commission (IEC) publication 651:1979 (type 1). The meter shall be set at “slow” response;
an integrating sound level meter effecting analog or digital integration of the squared signal over a given time interval meeting the requirements of IEC publication 804:1985 (type 1). The meter must be set at “fast” response; (L.N. 69 of 2023)
a sound level meter meeting the requirements of IEC publication 61672-1 (class 1). (L.N. 69 of 2023)
Microphone with cable
Use shall be made of a microphone with cable complying with IEC publication 651:1979 or 61672-1, and calibrated for free field measurement.
Weighting network
Use shall be made of an A-weighting network meeting the requirements of IEC publication 651:1979 or 61672-1.
Inspection of the measuring apparatus
Before the tests, the acoustic properties of the entire apparatus (measuring instruments including microphone and cable) shall be checked by means of a calibrated sound source with an accuracy of at least 0.5 dB (e.g. a pistonphone); the apparatus shall be checked again immediately after each series of measurements.
Operation of the appliance during measurements
The appliance shall be brought to its steady-state temperature within the range specified by the manufacturer. It shall be operated at its nominal speed and its nominal pressure.The nominal speed and pressure are those recommended by the manufacturer.
Measuring site
The measuring site must be flat and horizontal.
Measurement surface, measuring distance, location and number of measuring points
Measuring surface and measuring distance
The measuring surface to be used for the test shall be a hemisphere. The radius shall be—
4 m, where the greatest dimension of the appliance to be tested is not more than 1.5 m;
10 m, where the greatest dimension of the appliance to be tested is more than 1.5 m but not more than 4 m;
16 m, where the greatest dimension of the appliance to be tested is more than 4 m.
Location and number of measuring points
For the measurements there shall be 6 measuring points on a hemisphere of radius r, i.e. points 1, 2, 3, 4, 5 and 6 arranged as illustrated in Figures 1 and 2, with variations in the value of z of points as shown in Table 1.For testing of the appliance, the geometric centre of the appliance shall be positioned vertically above the centre of the hemisphere.The x-axis of the set of coordinates, in relation to which the positions of the measuring points are fixed, shall be parallel to the main axis of the appliance.The 6 measuring points shall have the following coordinates (Table 1) as measured from the centre of the hemisphere—
Table 1
| X | Y | Z | |
| 1 | r | 0.0 | 1.50 m |
| 2 | 0.0 | r | 1.50 m |
| 3 | r | 0.0 | 1.50 m |
| 4 | 0.0 | r | 1.50 m |
| 5 | 0.27 r | 0.65 r | 0.71 r + 1.5 m |
| 6 | 0.27 r | 0.65 r | 0.71 r + 1.5 m |
Measurement of extraneous noise
Only the background noise shall be taken into account for the purpose of corrections. Background noise shall be recorded at the measuring points (see paragraph 6.3.2) with the appliance switched off, i.e. no sound emission (see paragraph 7.2).
Measurement of the sound pressure level LpA
To measure the sound pressure level LpA, use shall be made of an instrument as defined in paragraph 5.2. If a sound level meter is used, 5 readings shall be taken at each measuring point. The mean value of these 5 readings shall be calculated in accordance with paragraph 11. If an integrating sound level meter is used, the integrating time shall be 15 seconds.
Calculation of root mean square values
Root mean square value at a measuring point
The values obtained from the measurements referred to in paragraph 7.2 are root mean square values in time.
Root mean square value on the measuring surface
The level corresponding to the root mean square value in space of the sound pressure levels for all the measuring points shall be calculated on the basis of the values established in accordance with paragraph 8.1.1.
Calculation of average extraneous noise level
The average extraneous noise level over the measuring surface is obtained by applying the method described in paragraph 8.1.2 to the extraneous noise levels established at the different measuring points.
Calculation of the area S of the measuring surface
The area S, expressed in m2, of the measuring surface is determined as follows—
S = 2π R2
The area of the measuring surface may be calculated approximately. It should be noted that an error of ± 20% in this area gives a deviation of ± 1 dB in the value of the term—
| 10 log10 | S | (surface level) | ||
| So |
Calculation of the surface sound pressure level LpAm
The surface sound pressure level is the level calculated in accordance with paragraph 8.1.2 and then corrected as described in paragraph 8.6.
Calculation of the sound power level LWA
The sound power level LWA of the sound source is calculated by means of the following equation—
| LWA | = | LpAm | + | 10 log10 | S | ||
| So |
Where—
| LWA | = | sound power level of the source tested, expressed in dB (see paragraph 3.4); |
| LpAm | = | the surface sound pressure level, expressed in dB, as defined in paragraph 3.3; |
| S | = | the area of the measuring surface in m2, calculated in accordance with paragraph 8.3; |
| So | = | reference area of 1 m2. |
Corrections to be made to measurements
The average sound pressure level over the measurement surface, calculated in accordance with paragraph 8.1, shall be corrected, if necessary, to take account of the extraneous noise determined in accordance with paragraph 8.2. The correction K1 in dB, which shall be subtracted from the average sound pressure level over the measuring surface is given in the table below.
| Difference in dB between the sound pressure level calculated when the appliance is operating and the sound pressure level due to extraneous noise alone | Correction K1 in dB |
| less than 6 6 7 8 9 10 more than 10 | no valid measurements 1.0 1.0 1.0 0.5 0.5 no correction |
To allow for tolerances, 5 dB(A) shall be deducted from the A-weighted sound power LWA determined for the appliance and the net result shall then be compared with the relevant standard.
A model report is provided in the Appendix.
The data shall be reported in accordance with paragraph 9. The report shall state clearly that the sound power levels were obtained in accordance with the test conditions. It shall specify that these sound power levels are given in A-weighted dB, reference 10-12 W.
The root mean square value of the various sound pressure levels resulting from a series of measurements made at different points on the measuring surface (root mean square in space) can be determined by the following formula—
| LpAm | = | LpAo | + | 10 log10 | 1 | i = n Σ gi i = 1 | |
| n |
| LpAi | = | the sound pressure level of the i-th measurement; |
| LpAo | = | an auxiliary sound pressure level to simplify the calculation (for example, the smallest of the LpAi values); |
| gi | = | the auxiliary variable for the i-th measurement— |
gi = 100.1(LpAi LpAo).
| Manufacturer | |
| Model | Serial No. |
| Description | Mass |
| Type: Compressed air, hydraulic, electric, petrol(1) | |
| Length | m | |
| Width | m | |
| Height | m | |
| Mass | kg |
Operating Conditions(1)
| Make and type | ||
| Energy used: petrol, diesel, electricity, gas(1) | ||
| Nominal speed | rpm | |
| Motor power | kW | |
| Make and type | |||
| Nominal speed at full load | rpm | ||
| Nominal delivery pressure | kPa | ||
| Nominal air flow at the above speed and pressure | |||
| m3/min | |||
(1) Delete as appropriate.
Test conditions
| Barometric pressure | Ambient temperature |
| Composition and dimensions of reflecting surface | |
| Remarks | |
Equipment
| Microphone | Serial No. | |
| Sound-level meter | Serial No. | |
| Calibrating equipment | Serial No. | |
| Miscellaneous (e.g. wind shield or recorder) | ||
| Serial No. | ||
Test Set up
Diagram showing microphone locations and, if applicable, the direction of the exhaust and the position of any large objects situated less than 25 m from the appliance under test.
Acoustic data
| —area S in m2 of measuring surface and value of | 10 log10 | S | ; |
| So | |||
| —sound-pressure levels measured at measuring points; | |||
| —average sound-pressure level over measuring surface; | |||
| —any corrections in decibels; | |||
| —surface sound-pressure level LpAm; | |||
| —sound-power level; | |||
| —date and time of measurements. | |||
Form 1
N C O (Chapter 400)APPLICATION FOR A NOISE EMISSION LABEL
FOR AIR COMPRESSOR
Before completing this form read the Notes below.
To: The Noise Control Authority
| 1. | I hereby apply for a noise emission label for an air compressor under the Noise Control Ordinance. | ||
| In support of my application I submit the following information and particulars: | |||
| 2. | Details of Applicant | ||
| 2a. | Name (person or company): | ||
| 2b. | H.K. Identity Card No. (if the applicant is an individual): | ||
| or Business Registration No. (if the applicant is a company): | |||
| 2c. | Correspondence address: | ||
| 2d. | Telephone No.: | ||
| 2e. | Email address: | ||
| 3. | Information on air compressor | ||
| 3a. | Name and address of manufacturer: | ||
| 3b. | Name and address of manufacturer’s authorized local representative (if any): | ||
| 3c. | Trade name: | ||
| 3d. | Model (see Note 1): | ||
| 3e. | |||
| Serial Number | |||
| 1. | |||
| 2. | |||
| 3. | |||
| 4. | |||
| 5. | |||
| Continue on separate sheet if necessary. Please state clearly each appliance serial number. | |||
| 3f. | Motor power (see Note 2): . kW | ||
| 3g. | Supporting document (see Note 3): | ||
| 4. | Application fee (see Note 4) | ||
| 4a. | Number of noise emission labels applied for: | ||
| 4b. | Total fee payable: | ||
| 5. | Additional information | ||
| Give any additional information which is thought to be relevant to this application: | |||
| Dated this . day of . 20 . | |||
| Signed | |
| Applicant. |
The applicant shall fill in an application form for each model.
The applicant shall submit all relevant trade leaflets, brochures or similar documents for the Authority’s consideration.
The applicant must submit for the Authority’s consideration either—
a noise testing report certificated by—
a corporate member of the Hong Kong Institute of Acoustics Limited;
a professional member of the Hong Kong Institute of Qualified Environmental Professionals Limited; or
a registered professional engineer (as defined by section 2(1) of the Engineers Registration Ordinance) in the building services, environmental or mechanical discipline,
that the testing was conducted in accordance with the conditions set out in Schedule 2 to the Noise Control (Air Compressors) Regulations; or
supporting documents showing that the air compressor complies with a standard that is substantially the same as or more stringent than that set out in Schedule 1 to the Regulations when tested under conditions comparable to those set out in Schedule 2 to the Regulations.
The applicant shall submit a fee of $530 for each label applied for. The fee payable on submission of this application will not be refunded. Cheques, drafts or cashier orders shall be made payable to “The Government of the Hong Kong Special Administrative Region” or “The Government of the HKSAR” and crossed.
Regulation 8(3) of the Noise Control (Air Compressors) Regulations provides that not later than 28 days after an application is received by the Authority, the Authority shall issue a noise emission label or labels applied for or serve on the applicant written notice of his refusal to issue the label or labels, and if at the end of those 28 days he has done neither of those things, a label or labels shall be deemed to have been issued.
A noise emission label that is issued in consequence of misleading, false, wrong or incomplete information furnished by an applicant in connection with the application is liable to be cancelled.
The applicant is advised to read the Noise Control Ordinance and the Noise Control (Air Compressors) Regulations.
| FOR OFFICE USE ONLY |
| Permissible limit, dB(A) (“P” stands for the motor power of the air compressor) | No. of labels issued | |
| 97 (P ≤ 15 kW) | ||
| 95 + 2 log P (15 kW < P < 350 kW) | 97 | |
| 98 | ||
| 99 | ||
| 100 | ||
| 102 (P ≥ 350 kW) | ||
(L.N. 260 of 1994; L.N. 65 of 1995; L.N. 497 of 1996; L.N. 582 of 1997; L.N. 308 of 2000; L.N. 184 of 2005; L.N. 101 of 2008; L.N. 43 of 2016; L.N. 69 of 2023)