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Technical Committee on Sound White Paper
Product Labeling and International Standards
- Implications and Benefits of an ARI “Labeling” Procedure
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September 7, 2001
Overview
Product labeling is certainly not a new concept. We all see product labeling
when we purchase consumer products, usually related to energy consumption.
Product labeling in essence is an approach or procedure to give the end user
confidence that they have correct, consistent comparison information for making
decisions between competitive product offerings. What is new, however, is the
need for a standardized “labeling” procedure to be followed when determining a
sound rating number for a product that can be designed, tested and
manufactured any place in the world. Without an ARI “labeling” Procedure in
International HVAC Sound Standards, the sound rating information provided to
the end user will not be in a comparable form between different manufacturers or
locations.
Historically, in the United States, it has been the responsibility of each HVAC
manufacturer to identify their own internal strategy whereby they developed a
rating procedure based upon knowledge of their product. This is a valid and
desirable approach when the basic sound measurements themselves are all
made in the same way. Simply stated, this means that all values that form the
basis of a rating number are obtained through measurements made in
accordance with a single industry standard utilizing a single measurement
methodology. In the United States, the HVAC community follows procedures
and methodologies specified in ARI measurement and rating standards.
Today’s HVAC manufacturers function in a global business environment that no
longer lends itself to simple solutions to seemingly simple problems like product
labeling. HVAC companies design and test product in literally every corner of the
world. Since the HVAC market is quite mature, many countries have developed
their own sound test and rating methods, many of which differ from those
developed and used in the United States. This does not mean that these other
sound test methods are invalid or even that they are inferior. Most often they are
very good methods and are based upon solid engineering principles and sound
judgement. The fact remains, however, that these methods can differ from each
other and usually differ from those used in the United States. Unfortunately
these differences can produce rating values that cannot be directly compared
with each other and herein lies the heart of the problem.
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Product sound rating numbers are most commonly used to compare the sound
level of one product to that of another. Since it is well known in the acoustics
community that different test methods can result in different rating numbers, it is
obvious that either a single method must be used throughout the industry or that
a process must be identified that will account for differences in the various test
methods thus allowing a valid comparison of rating numbers to be made.
For many years, ARI has been formally addressing problems associated with
“globalization” of the HVAC industry by working to develop ISO test and rating
standards that reflect ARI’s philosophy while at the same time establishing
international support. As the first sound measurement and rating standards were
being drafted, it quickly became evident that the international community was not
about to unilaterally adopt only the acoustic measurement and rating methods
used in the United States. There were good reasons for this decision so it was
virtually impossible to obtain consensus among the drafting committee members
unless multiple sound measurement and rating methods were included as part of
the standards.
As drafting committee discussions took place trying to resolve issues associated
with the use of multiple methods in the area of sound measurements, it was
learned that the international community had already addressed this problem.
ISO 4871, “Acoustics – Declaration and Verification of Noise Emission Values of
Machinery and Equipment” was developed for just this purpose. ISO 4871
clearly identifies a general “labeling” process whereby the variability in a
measured value caused by inherent differences in the measurement procedures
themselves is accounted for. Additionally, it describes a procedure to be
followed to account for product variability. When the rating process in ISO 4871
is followed, it results in what is called a “Declared Noise Emission Value”, which
is the “Label Value” associated with a particular piece of equipment. This
declared value can be directly and equitably compared with any other declared
value derived following the same procedure.
There is no question that use of an ARI “labeling” procedure based on ISO 4871
will result in a more complicated sound rating procedure, but without it our
customers in the global HVAC market will make purchasing decisions that may
be flawed because they are based upon misinterpreted data. Sound
measurement methods used in the United States for sound ratings tend to be of
a higher precision level then those made elsewhere in the world. Without a
“labeling” process, the variabilities and bias of other measurement methods can
actually make the US sound rating numbers at a disadvantage or even appear
higher than rating numbers generated on the same piece of equipment
elsewhere. We simply cannot afford to have this happen and the use of an ARI
“labeling” procedure based on ISO 4871 to develop fair and equitable product
sound rating labels is the best tool that we have available to prevent it.
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Technical Details - Proposed ARI “Labeling” Procedure/Standard
The proposed standard would provide guidelines for obtaining information on the
acoustic noise emission of air-conditioning units, heat pumps, and refrigeration
equipment from their manufacturers. The purpose of the labeling standard is to
assist the user in obtaining reliable, accurate, consistent, and timely sound level
information from manufacturers of HVAC machinery and equipment. It assists
the users in interpreting the information to make appropriate decisions. The
proposed standards will be intended for users evaluating HVAC equipment
sound levels.
The proposed labeling standard will be consistent with ARI and ISO standards.
The relevant declared sound level value will be known as the Published Sound
Rating (PSR). The PSR is the information on noise emission values given by
manufacturer in technical documents of the HVAC products. PSR will be made
in accordance with ISO 4871, ISO 7574, ANSI S12.16-1992, and ANSI-12.XX-
200X procedures. Annexes will be added to the proposed standard so as to
comply with the USA, ARI manufacturers and market demands and
requirements. ARI will therefore accept the ISO labeling standards, but will
include the USA noise emission measurement as one of its multiple sound
measurement methods. It should be noted that the PSR is different from the
Measured Sound Rating (MSR). The MSR is an A-Weighted sound power level
determined from measurements made in accordance with ANSI S12.31, 32 and
ISO 3741, ISO 3742, ARI 350 and ARI 270. MSR includes the tone adjusted, AWeighted
sound power level and the octave band sound power level for each
band over a given frequency range.
The proposed labeling standard would provide the following ramifications for
HVAC equipment users:
• Declaration and verification of noise emissions values from different HVAC
products. The values are either declared single, dual, and sequential number
noise emission values, declared dual noise emission values (including
uncertainty values), or declared sequential noise emission values.
• Providing the noise information relating to global environmental noise
requirements. It would create a uniform method for noise emission
measurements (A-Weighted sound power level determined from
measurements, the tone adjusted A-weighted sound power level and the
octave band sound power level for each bands over a given frequency
range).
• Providing the PSR for users in technical documents of the HVAC machinery
and equipment. Because of measurement uncertainty, the PSR would not be
the same as the MSR obtained for a single HVAC machine or equipment.
The PSR would be the sole responsibility of the manufacturers.
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• A uniform presentation of the PSR can be developed after the PSR
determination. The noise emission declarations will contain identification of
the HVAC machinery and equipment, identification of the respective noise
code, and identification of the respective operating conditions.
• The verification procedure should be coupled to the uniform presentation of
the PSR so that the manufacturer can estimate the risk of failure for the
verification process, if there is different between reference standard deviation
and total standard deviation. The verification procedure should also include
the expenses and the degree of the complexity associated with the testing of
the HVAC machinery and equipment.
• Providing guidelines for determining the labeled value by labeler and
specification of a simple method for verifying compliance of the noise
emission of a batch of HVAC machinery or equipment with its labeled value.
Statistical sampling procedures and assuming a normal distribution can be
used to check the labeled value for all machines in a batch.
• When checking the compliance of a batch with its labeled value, the labeled
value indicates the limit below which a specified (large) proportion of the
noise emission values of the batch shall be. The proportion accounts for both
the variability between the machines and the random measurement errors
occurring under reproducibility conditions.
• The statistical methods for determining and verifying labeled noise emission
values are based on the basis of clearly defined acoustical measurement
methods and describe the handling of the variability of measurement results
and, if relevant, of the noise emissions of HVAC machines or equipment in a
batch. The statistical methods can also be applied to values stated for the
upper noise limit of a specific family of machines, and to contract values as
agreed by manufacturer and purchaser of HVAC machines or equipment.
• The stated value is given either for one individual HVAC machine or
equipment or for an entire batch of machines and equipment.
• The statistical methods apply:
o Standard deviation of reproducibility (same noise source at different
times and under different conditions, different laboratory, different
operator, different noise measurement apparatus), which includes the
standard deviation of repeatability (same noise source, same operator,
same laboratory, same noise measurement apparatus).
o Standard deviation of production uses different noise emission
sources. It is obtained on different machines from a batch, using the
same noise emission measurement method under repeatability
conditions.
• Providing a total standard deviation specified for the family of HVAC
machines or equipment under consideration, which is considered to be
typical for batches from this family. The total standard deviation is calculated
from standard of production and the standard deviation of reproducibility. A
higher precision noise emission measurement method will produce lower
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standard deviation of reproducibility (the measured noise emission value will
therefore be a smaller value).
• The use of a fixed reference standard deviation for each family of machines
or equipment enables the application of a statistical method to deal with small
sample size. Typical values of reference standard deviation range from 1.5
to 3.5 dB depending on the precision of the measurement method. If there is
no prior knowledge of the standard deviation of production or there is no
reference standard deviation determined for the family of machines under
consideration, the uncertainty, in decibels, should be applied (ISO 4871).
• The upper-limit measured noise emission values can be obtained as the sum
of the mean value and uncertainty. The uncertainty value will be smaller for a
precise noise measurement method.
Conclusion
Without the proposed labeling standard there would not be uniform methods for:
1) determination of the published sound rating values
2) presentation of published sound rating values
3) verification of published sound rating values
4) the use of statistical methods for determining and verifying compliance
of the noise emissions of a batch of HVAC machinery and equipment
with its labeled value
5) proposing labeling standards consistent with those of the ISO labeling
standard.
Therefore, lack of this standard would cause confusion for both manufacturers
and users in the interpretation of the HVAC equipment’s sound information in the
global range.
Comment
ARI should conform to the requirements of ISO 4871 and ISO 7574 for labeling.
Annexes can be added to the proposed standard so as to comply with the USA
ARI manufacturers and market demands and requirements.
References
1. ANSI Standard S12.16-1992 (R1997), Guidelines for the Specification of
Noise of New Machinery, American National Standards Institute, 25 West
43rd Street, 4th Fl., New York, New York, 10036, U.S.A.
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2. ANSI S12.31-1990 (R1996), Precision Methods for the Determination of
Sound Power Levels of Broad-Band Noise Sources in Reverberation Rooms,
American National Standards Institute, 25 West 43rd Street, 4th Fl., New
York, New York, 10036, U.S.A.
3. ANSI S12.32-1990 (R1996), Precision Methods for the Determination of
Sound Power Levels of Discrete-Frequency and Narrow-Band Noise Sources
in Reverberation Rooms, American National Standards Institute, 25 West
43rd Street, 4th Fl., New York, New York, 10036, U.S.A.
4. ANSI S12.61-200 (draft dated August 23, 2001), Declaration and Verification
of Noise Emission Values of Machinery and Equipment, American National
Standards Institute, 25 West 43rd Street, 4th Fl., New York, New York,
10036, U.S.A.
5. ARI Standard 270-95, Sound Rating of Outdoor Unitary Equipment, 1995, Air-
Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425,
Arlington, VA 22203, U.S.A.
6. ARI Standard 350-2000, Sound Rating of Non-Ducted Indoor Air-
Conditioning, 2000, Air-Conditioning and Refrigeration Institute, 4301 North
Fairfax Drive, Suite 425, Arlington, VA 22203, U.S.A.
7. ISO 3741, Acoustics -- Determination of Sound Power Levels of Noise
Sources -- Precision Methods for Broad-Band Sources in Reverberation
Rooms, 1988, International Organization for Standardization, 1, rue de
Varembe, Case postale 56, CH-1211 Geneva 20, Switzerland.
8. ISO 3742, Acoustics -- Determination of Sound Power Levels of Noise
Sources -- Precision Methods for Discrete-Frequency and Narrow-Band
Sources in Reverberation Rooms, 1988, International Organization for
Standardization, 1, rue de Varembe, Case postale 56, CH-1211 Geneva 20,
Switzerland.
9. ISO 4871, Acoustics – Noise Labelling of Machinery and Equipment, 1984,
International Organization for Standardization, 1, rue de Varembe, Case
postale 56, CH-1211 Geneva 20, Switzerland.
10. ISO 7574-1, Acoustics – Statistical Methods for Determining and Verifying
Stated Noise Emission Values of Machinery and Equipment – Part 1: General
Considerations and Definitions, 1985, International Organization for
Standardization, 1, rue de Varembe, Case postale 56, CH-1211 Geneva 20,
Switzerland.
11. ISO 7574-2, Acoustics – Statistical Methods for Determining and Verifying
Stated Noise Emission Values of Machinery and Equipment – Part 2:
Methods for Stated Values for Individual Machines, 1985, International
Organization for Standardization, 1, rue de Varembe, Case postale 56, CH-
1211 Geneva 20, Switzerland.
12. ISO 7574-3, Acoustics – Statistical Methods for Determining and Verifying
Stated Noise Emission Values of Machinery and Equipment – Part 3: Simple
(Transition) Method for Stated Values for Batches of Machines, 1985,
International Organization for Standardization, 1, rue de Varembe, Case
postale 56, CH-1211 Geneva 20, Switzerland.
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13. ISO 7574-4, Acoustics – Statistical Methods for Determining and Verifying
Stated Noise Emission Values of Machinery and Equipment – Part 4:
Methods for Stated Values for Batches of Machines, 1985, International
Organization for Standardization, 1, rue de Varembe, Case postale 56, CH-
1211 Geneva 20, Switzerland.