This International Standard specifies methods for measuring airborne acoustical noise emitted by electric refrigerators, frozen-food storage cabinets, food freezers and their combinations for household and similar uses, supplied from the mains or from batteries.
The term "similar use" means "use under condi-tions similar to those in a household", e.g. in cafes, restaurants, hotels and similar establishments.
This International Standard does not apply to ap-pliances, equipment or machines designed exclu-sively for industrial or commercial purposes.
This International Standard is concerned with ob-jective methods of engineering accuracy (engineer-ing method, grade 2 according to ISO 2204) for determining sound power levels, Lw, expressed in decibels with reference to a sound power of 1 pW, of airborne acoustical noise wilhin the specified fre-quency range of interest, and for specified operating conditions of the appliance to be measured.
The frequency range of interest includes the octave bands with centre frequencies between 125 Hz and 8 000 Hz (this interval being, for practical reasons, narrower than the frequency range of audible sound).
The following sound power levels are used:
— A-weighted sound power level, LWA, and
— octave band sound power levels, /^0ct
In general, the methods described are specified for appliances operated with no operator present.
The noise measurements are made while the com-pressors are running.
Requirements as to an indication of the noise emission values are not the subject of this Inter-national Standard.
NOTES
1 The uncertainties of measurement according to this International Standard usually result, for A-weighted sound power levels, in standard deviations generally not exceeding approximately 2 dB, provided that the noise spectrum does not contain pronounced discrete frequen-cies; if it does, the magnitude of the uncertainties will be larger. The standard deviations referred to reflect the cu-mulative effects of all causes of measurement uncertain-ties, excluding variations in the noise level of the appliance from test to test.
2 The noise values obtained under the conditions de-scribed in this International Standard will not necessarily correspond with the noise experienced under the opera-tional conditions of practical use (see 6.4.1).
3 For quality control during production, etc., simplified methods may be appropriate. For noise control purposes (e.g. development of quieter appliances, insulation of equipment, etc.), other measurement methods using, for example, narrow-band frequency analysis will usually have to be applied. These methods are not covered in this International Standard.
This International Standard does not include meth-ods for determining sound power levels with pre-cision accuracy (precision method, grade 1 according to ISO 2204) specified, for example, in ISO 3741, ISO 3742 and ISO 3745; they may, how-ever, be applied if the appropriate instrumentation and test environment are available.