1、BRITISH STANDARD BS5944-6: 1992 ISO4412-3: 1991 Measurement of airborne noise from hydraulic fluid power systems and components Part6: Method of test for pumps using a parallelepiped microphone array UDC 621.65:534.6BS5944-6:1992 This British Standard, having been prepared under the directionof the
2、Machinery andComponents Standards PolicyCommittee, was publishedunder the authorityofthe Standards Boardand comes into effect on 15 December1992 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference MCE/18 Draft for comment 89/78174DC ISBN 0 580 21395 1 Co
3、mmittees responsible for this British Standard The preparation of this British Standard was entrusted by the Machinery and Components Standards Policy Committee(MCE/-) to Technical Committee MCE/18, upon which the following bodies were represented: Advanced Manufacturing Technology Research Institut
4、e Association of British Mining Equipment Companies Bath University British Compressed Air Society British Fluid Power Association British Steel Industry Department of Trade and Industry(National Engineering Laboratory) Ministry of Defence The following bodies were also represented in the drafting o
5、f the standard, through subcommittees and panels: British Hydromechanics Research Association British Railways Board Society of Motor Manufacturers and Traders Ltd. Amendments issued since publication Amd. No. Date CommentsBS5944-6:1992 BSI 10-1999 i Contents Page Committees responsible Inside front
6、 cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Measurement uncertainty 2 5 Test environment 2 6 Instrumentation 2 7 Installation conditions 2 8 Operating conditions 3 9 Location and number of sound measurement points 3 10 Test procedure 3 11 Calculati
7、on of surface sound pressure levels and sound power levels 5 12 Information to be recorded 5 13 Test report 6 14 Identification statement 6 Annex A (normative) Errors and classes of measurement 7 Annex B (informative) Bibliography 7 Figure 1 Microphone array on rectangular parallelepiped measuring s
8、urface 4 Table 1 Standard deviation of sound power level determinations 2 Table 2 Allowable variations of mean indicated values of controlled parameters 3 Table 3 Coordinates of microphone locations shown in Figure 1 3 Table A.1 Permissible systematic errors of measuring instruments as determined du
9、ring calibration 7 List of references Inside back coverBS5944-6:1992 ii BSI 10-1999 National foreword This Part of BS5944 has been prepared under the direction of the Machinery and Components Standards Policy Committee. It is identical with ISO4412-3:1991 Hydraulic fluid power Test code for determin
10、ation of airborne noise levels Part3: Pumps Method using a parallelepiped microphone array, published by the International Organization for Standardization(ISO). BS5944 comprises the following Parts. Part1: Method of test for pumps; Part2: Method of test for motors; Part3: Withdrawn; Part4: Method o
11、f determining sound power levels from valves controlling flow and pressure; Part5: Simplified method of determining sound power levels from pumps using an anechoic chamber; Part6: Method of test for pumps using parallelepiped microphone array. For the purposes of the British Standard the identificat
12、ion statement required by clause14 may be replaced by the following: “Airborne noise levels determined in accordance with BS5944-6” The Technical Committee has reviewed the provisions of ISO5598:1985 to which reference is made in the text and has decided that they are acceptable for use in conjuncti
13、on with this standard. There are no corresponding British Standards for ISO5598. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself
14、confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO3448:1975 BS4231:1982 Classification for viscosity grades of industrial liquid lubricants (Identical) ISO3744:1981 BS4196 Sound power levels of noise sources Part4:1981 Engineering metho
15、ds for determination of sound power levels for sources in free-field conditions over a reflecting plane (Identical) ISO6743-4:1982 BS6413 Lubricants, industrial oils and related products(Class L) Part4:1983 Classification for family II (hydraulicsystems) (Identical) IEC651:1979 BS5969:1981 Specifica
16、tion for sound level meters (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated
17、 in the amendment table on the inside front cover.BS5944-6:1992 BSI 10-1999 1 Introduction In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure in a closed circuit. Pumps are components which convert rotary mechanical power into fluid power. During th
18、e process of converting mechanical power into hydraulic fluid power, airborne noise, fluid-borne vibrations and structure-borne vibrations are radiated from the pump. The airborne noise level of a hydraulic fluid power pump is an important consideration in component selection. The noise measurement
19、technique should, therefore, be such as to yield accurate appraisals of these airborne noise levels. The determination of noise levels is complicated by the interactions which occur during noise measurements. The fluid-borne and structure-borne vibrations from the pump can be transmitted to the circ
20、uit and ultimately give rise to background airborne noise levels which could affect the determination of the pump airborne noise levels. The procedures described in this part of ISO4412 are intended to measure only the airborne noise radiated directly from the pump under test. This part of ISO4412 c
21、losely follows the methods described in the two other parts, but allows the use of alternative pump mounting and drive configurations which are simpler and cheaper to implement in an anechoic chamber. Much of the guidance given in ISO4412-1:1991, Annex C, is equally applicable to this part of ISO441
22、2. The data obtained have been shown to be sufficiently accurate in engineering terms for A-weighted and one-third octave noise measurements, in decibels. This part of ISO4412 may also be applied to the testing of motors. 1 Scope This part of ISO4412 describes procedures for the determination of the
23、 sound power levels of a hydraulic fluid power pump, under controlled conditions of installation and operation, suitable for providing a basis for comparing the noise levels of pumps in terms of A-weighted sound power level; one-third octave band power level. From these sound power levels, if requir
24、ed, reference sound pressure levels may be calculated for reporting purposes(seeclause11). For general purposes, the frequency range of interest includes the one-third octave bands with centre frequencies between100Hz and10000Hz 1) . This part of ISO4412 is applicable to all types of hydraulic fluid
25、 power pumps operating under steady-state conditions, irrespective of size, except for any limitations imposed by the size of the test environment(seeclause3). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part
26、of ISO4412. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO4412 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IE
27、C and ISO maintain registers of currently valid International Standards. ISO3448:1975, Industrial liquid lubricants ISOviscosity classification. ISO3744:1981, Acoustics Determination of sound power levels of noise sources Engineering methods for free-field conditions over a reflecting plane. ISO5598
28、:1985, Fluid power systems and components Vocabulary. ISO6743-4:1982, Lubricants, industrial oils and related products(class L) Classification Part4:Family H(Hydraulic systems). IEC651:1979, Sound level meters. 3 Definitions For the purposes of this part of ISO4412, the definitions given in ISO5598
29、and the following definitions apply. It is accepted that the latter definitions may differ from those in other specific International Standards. 3.1 free sound field sound field in a homogeneous, isotropic medium free of boundaries NOTE 1In practice, it is a field in which the effects of the boundar
30、ies are negligible over the frequency range of interest. 3.2 free field over two reflecting planes field produced by a source in the presence of two mutually perpendicular reflecting planes 3.3 anechoic room test room having boundaries which absorb essentially all of the incident sound energy over t
31、he frequency range of interest, thereby affording free-field conditions over the measurement surface 1) 1Hz=1s 1BS5944-6:1992 2 BSI 10-1999 3.4 mean-square sound pressure the sound pressure averaged in space and time on a mean-square basis NOTE 2In practice, this is estimated by space and time avera
32、ging over a finite path length or over a number of fixed microphone positions. 3.5 mean sound pressure level (L p ) ten times the logarithm to the base10 of the ratio of the meansquare sound pressure to the square of the reference sound pressure, in decibels(dB) NOTE 3The weighting network or the wi
33、dth of the frequency band used should always be indicated; for example, A-weighted sound pressure level, octave band sound pressure level. The reference sound pressure is204Pa 2) . 3.6 sound power level L w ten times the logarithm to the base10 of the ratio of a given sound power to the reference so
34、und power, in decibels(dB) NOTE 4The weighting network or the width of the frequency band used should always be indicated. The reference sound power is1pW 3) . 3.7 volume of source under test volume of the envelope of the whole pump under test 3.8 reference box hypothetical reference surface which i
35、s the smallest rectangular parallelepiped that just encloses the pump and any large directly-attached appendages(such as valve bodies or control handwheels) and which terminates on the reflecting planes 4 Measurement uncertainty With the exception of the measurement environment specified in clause5,
36、 use methods of measurement which tend to result in standard deviations which are equal to or less than those given in Table 1. To meet this requirement, use the engineering methods given in ISO3744:1981, clause 4 and Annex A. Table 1 Standard deviations of sound power level determinations The stand
37、ard deviations given in Table 1 include the effects of allowable variations in the positioning of the measurement points and in the selection of any prescribed measurement surface, but exclude variations in the sound power output of the source from test to test. NOTE 5The A-weighted sound power leve
38、l will in most practical cases be determined with a standard deviation of approximately2dB. 5 Test environment Tests shall be conducted in an environment generally in accordance with that described in ISO3744 and which provides free-field conditions over two mutually perpendicular reflecting planes,
39、 both of which extend beyond the projected area of the microphone measuring array. Calibrate the acoustic test environment thus formed and ascertain the environmental corrections for each frequency band of interest, using the procedures described in ISO3744:1981, Annex A. 6 Instrumentation 6.1 The i
40、nstrumentation used to measure fluid flow, fluid pressure, pump speed and fluid temperature shall be in accordance with the recommendations for “industrial class” accuracy of testing; i.e.class C given in Annex A. 6.2 The instrumentation used for acoustical measurements shall be in accordance with I
41、EC651. This instrumentation shall be in accordance with ISO3744 for both performance and calibration; i.e.type2 instruments for engineering(grade2) measurements. 7 Installation conditions 7.1 Pump location The pump shall be located with its mounting flange flush with one reflecting plane. The second
42、 reflecting plane shall be arranged so as to intersect the first at right angles as close to the pump as practicable. 2) 14Pa=10 6 N/m 2 3) 1pW=10 12 W Standard deviation, dB, for one-third octave band centre frequencies 100Hz to 160Hz 200Hzto 630Hz 800Hz to 5000Hz 6300Hz to 10000Hz 5,0 3,0 2,0 3,0B
43、S5944-6:1992 BSI 10-1999 3 7.2 Pump mounting 7.2.1 The pump mounting shall be constructed so that it will minimize the noise radiated as a result of pump vibrations. 7.2.2 The mounting bracket shall be constructed of high damping material, or with sound-damping and sound-insulating material applied
44、to the bracket as required. 7.2.3 Vibration isolation techniques, if needed, shall be used even if the pump is usually securely mounted. 7.3 Pump drive The drive motor shall be located outside the test space and the pump shall be driven through flexible couplings and an intermediate shaft, or the mo
45、tor shall be isolated in an acoustic enclosure. 7.4 Hydraulic circuit 7.4.1 The circuit shall include all oil filters, oil coolers, reservoirs and restrictor valves as required to meet the pump hydraulic operating conditions(seeclause8). 7.4.2 The test fluid and degree of filtration shall be in acco
46、rdance with the manufacturers recommendations. 7.4.3 Inlet and discharge lines shall be installed with diameters in accordance with the manufacturers” recommended practice. Extra care shall be exercised when assembling inlet lines to prevent air leaking into the circuit. 7.4.4 The inlet pressure gau
47、ge shall be mounted at the same height as the inlet fittings or it shall be calibrated for any height difference. 7.4.5 The length of line between the pump and the load valve shall be selected in order to minimize the effect of standing waves in the discharge line which can increase the sound radiat
48、ed from the pump. At least15m of hose shall be used to meet this requirement. 7.4.6 A stable load valve shall be used. NOTE 6Unstable load valves in the discharge line can generate and transmit noise through the fluid and piping which can emerge as airborne sound at the pump. 7.4.7 The load valve sh
49、all be positioned as far as possible from the pump, preferably outside the test room, to minimize interaction. The load valve shall be located close to the pump only when adequate control of its acoustic performance can be provided. 7.4.8 All fluid lines and load valves in the test space shall be wrapped with sound-isolating materials, if required(see10.1). Material having a sound-transmission loss of at least10dB at125Hz, and a greater loss at higher frequencies, shall be used. 8 Operating conditions 8.1 Determine the sound power
