Microsoft Word ISO 15664 E doc Reference number ISO 15664 2001(E) © ISO 2001 INTERNATIONAL STANDARD ISO 15664 First edition 2001 05 01 Acoustics — Noise control design procedures for open plant Acoust[.]
General terms
The end-user party is responsible for initiating the project and ultimately owns or operates the plant, or finances its design and construction Typically, the end-user outlines the technical objectives and requirements for the project.
3.1.2 contractor party which carries out all or part of the design, engineering, procurement, construction and commissioning for the project
3.1.3 manufacturer supplier party which manufactures or supplies equipment and services to perform the duties specified by the contractor
In the work area, it is essential to maintain a distance of at least 1 meter from equipment surfaces that are accessible to personnel Additionally, any position where a worker's ear may be exposed to noise during their normal duties should be carefully considered to ensure safety and compliance with noise exposure regulations.
NOTE The work area includes any platform, walkway or ladder.
3.1.5 project specification document defining the scope of a project
NOTE It can contain descriptions of the process, project management, responsibilities and engineering requirements. These include safety and environmental requirements.
3.1.6 governing authorities local, regional, national or other authorities that specify and enforce criteria for environmental and occupational health noise
Terms specific to noise
3.2.1 noise limit noise levels not to be exceeded and given as a sound power level, sound pressure level or noise exposure level
3.2.1.1 authority noise limits noise limits set by governing authorities
3.2.1.3 contractual noise limits noise limits set by the end-user as part of a legal contract between the end-user and the contractor, considering authority noise limits and company requirements
3.2.1.4 equipment noise limits noise limits set by an end-user or contractor for a manufacturer/supplier for an individual equipment item
3.2.2 tonal noise noise which is dominated by one or several clearly distinguishable tone(s)
3.2.3 impulsive noise noise consisting of one or more bursts of sound energy of duration less than about 1 s
NOTE See ISO 1996-2 (environmental noise), ISO 1999 (in-plant noise) and ISO 12001 (equipment emission).
3.2.4 fluctuating noise noise whose level varies continuously and to an appreciable extent during the period of observation
3.2.5 intermittent noise noise whose level abruptly drops to the level of the background noise several times during the period of observation
NOTE The time during which the level remains at a constant value different from that of the ambient is of the order of 1 s or more.
3.2.6 noise emission airborne sound radiated by well-defined noise source, such as a machine, equipment, part of a plant or an entire plant
NOTE See ISO 12001 and ISO 11690-1.
3.2.7 noise immission total amount of noise from all contributing sources at a given position
3.2.8 noise exposure all noises that arrive, over a specific time period,T, at a person’s ear in the actual situation
NOTE See ISO 11690-1; for the purposes of this International Standard, this term is also used for specific positions in the environment.
Controlling noise in a plant is essential to prevent noise-induced hearing loss, minimize interference with work, speech, and concentration, and ensure a quiet living environment for personnel.
`,,```,,,,````-`-`,,`,,`,`,,` - ắ to protect the environment; ắ to prevent annoyance to the neighbouring community.
General noise limits are established for various aspects of noise control, applicable to specific areas within or outside the plant, as outlined in clause 5 of this International Standard.
Equipment noise limits are determined based on general noise limits relevant to the specific location of the equipment within the plant These limits, known as "equipment noise limits," are established through procedures outlined in clause 6.
Each potential noise source shall be subject to the requirements of this International Standard.
Authorities can mandate noise reduction measures to the extent that it is feasible National and international standards, such as ISO 11690-1 for workplaces, ISO 9921-1 for speech communication, and the ISO 1996 series for environmental noise, provide guidelines for acceptable noise limits.
The design operating conditions of the plant must adhere to specified limits, which also apply to occasional operating scenarios like start-up, shutdown, regeneration, and maintenance, unless otherwise agreed upon by the end-user and contractor In emergency situations, such as relief valve operation, the only requirement is that the absolute limit outlined in section 5.1.2 must not be exceeded.
The end-user may set specific noise limits applicable to the construction phase of the project These limits may be set to meet environmental requirements.
This International Standard addresses noise generated by stationary equipment, but it is essential to also consider noise from mobile sources, such as transportation vehicles and mobile maintenance equipment within plants or workshops The impact of mobile noise sources increases significantly when a high volume of vehicles is present near plant boundaries, making noise reduction more challenging Consequently, it is crucial for stakeholders to assess whether transportation noise should be included in their noise control strategies.
The planning for and extent of the noise control engineering for a plant is based heavily on the project specification.
Clearly defining all noise limits and requirements in the project specification is crucial, especially when multiple contractors are involved or when the plant may be operated by parties other than the end-user Additionally, the specification should encompass all relevant items from annex C to ensure comprehensive compliance.
This International Standard outlines specific tasks to be carried out during a project, each designated with an action item label (A1, A2, A3, etc.) Responsibility for these action items is allocated to either the end-user or the contractor, as detailed in annex B, which provides a summary of the action items.
5 General noise limits (immission requirements)
In-plant noise
The end-user must thoroughly examine all regulations set by governing authorities regarding noise in the facility, including aspects related to hearing conservation, speech and work interference, and acceptable noise levels for accommodation.
Noise limits are typically determined by the noise exposure experienced by workers, necessitating agreement on work patterns that contribute to this exposure among all parties involved Additionally, these limits can be established based on the maximum sound pressure levels permitted in work areas.
The governing authorities and end-users will establish the strictest noise limits and requirements The project specification will clearly outline the relevant contractual noise limits.
Where there are no authority limits, the guidelines of ISO 11690-1 and other International Standards should be considered.
5.1.2 Absolute work area noise limit
The absolute limit refers to the maximum sound pressure level permitted in the work area, which must not be surpassed under any circumstances, including emergencies such as the activation of safety equipment.
The absolute limit is determined in action item (A2).
The noise limit in the workplace varies by area and establishes the maximum permissible noise level to ensure compliance with the standards outlined in action item (A2).
Restricted areas in a plant are designated work zones where it is not feasible to lower the noise levels to acceptable limits, as determined by current industry standards In these areas, the established noise limits must still be adhered to.
To minimize the impact of exceeding work area limits around specific equipment, it is essential to take measures to restrict the affected area as much as possible, both economically and technically One effective solution is the installation of an acoustic enclosure, which may also designate the enclosed areas as restricted zones.
The contractor must identify potential restricted areas for the end-user and obtain written permission to designate these areas Additionally, the contractor and end-user should collaboratively agree on permissible noise levels in these restricted zones, considering relevant authority requirements.
Permanent warning signs indicating the mandatory use of ear protectors will be installed at the boundaries of restricted areas, following the specifications outlined in ISO 3864.
Environmental noise
Environmental noise limits are established by regulatory authorities and are typically associated with current noise levels These regulations often outline measurement and calculation methods for assessing environmental noise immission, which is based on the sound power produced by various noise sources Additionally, they may stipulate the need for permits and environmental assessments, as referenced in ISO 1996-1 and ISO 1996-2.
(A5) The end-user shall investigate applicable regulations In order to avoid misunderstandings, it can be useful to discuss the interpretation of the regulations with the authorities.
Environmental noise regulations vary by time of day, including distinctions for daytime, evening, and nighttime, as well as weekends It is essential to consider all these factors to ensure compliance with the noise limits at all times.
In the absence of established environmental noise requirements, it is crucial to address this factor during the project definition phase of plant design to mitigate potential negative community responses in the future.
Authorities set environmental noise limits for both normal and emergency operations, defined as sound pressure level limits at specific locations near the plant or along its boundary These limits can be translated into contractual noise limits based on sound power levels for various components of the plant Consequently, the resulting sound power level limits must be incorporated into the project specifications.
The assessment of environmental noise immission, based on source sound power levels, must adhere to established calculation models approved by relevant authorities and users Notable examples of these recognized methods include those outlined in ISO 9613-2, which can be found in the Bibliography.
There are various methods to translate sound pressure level limits into sound power level limits for the assembly of plant components or large equipment Typically, these sound power level limits need to be defined in terms of octave or one-third-octave spectra, and they must also incorporate directivity constraints.
Exceptional or emergency operating conditions
The project specification must incorporate allowances for occasional higher noise levels that governing authorities may deem acceptable, particularly during emergencies, start-up, shutdown, and maintenance activities.
(A9) Any noise limits applicable during construction of the plant shall be stated separately in the project specification.
Additional restrictions for tonal or impulsive noise
Further restrictions may apply if the noise contains tonal or impulsive components and these shall be taken into account when specifying equipment noise limits (see 6.3.5).
6 Equipment noise limits (emission requirements)
General
Equipment noise limits must be established based on the noise immission or exposure limits of the work area and the sound power level limits specified in the project documentation.
If the investigation results show that noise limits may be exceeded, it is advisable to replace the noisy equipment with quieter alternatives If replacement is not feasible, implementing noise control measures like insulation or acoustic enclosures is recommended The level of these noise control measures should correspond to the severity of the noise requirements.
Sound power level limit for equipment
In facilities where the only applicable limitation is the work area limit and where significant noise sources are not in close proximity, it is unnecessary to determine the equipment sound power level limit.
The sound power level limit for individual equipment shall be determined at an early stage of the project in order to comply with the noise limits of the plant.
Effective allocation of sound power level limits for equipment should begin early in a project, utilizing vendor data, noise declarations (such as ISO 4871), databases, and relevant experience, while considering the equipment's type, size, and operating conditions When actual sound power levels are available, they should be prioritized; alternatively, these levels can be derived from the equipment's sound pressure levels, ensuring compliance with the specified requirements.
The derivation of sound power level limits for equipment is an iterative process, requiring that the total sound power limits for all equipment in a plant do not exceed a specified overall limit In the absence of a defined sound power level limit, the total environmental immission sound pressure level at relevant locations must be predicted The sound pressure levels from each noise-producing item can be summed at the community location of interest Noise propagation calculations should follow recognized models, such as ISO 9613-2, as agreed upon by authorities and end-users This analysis allows for adjustments to individual equipment sound power level limits to ensure compliance with community sound pressure level limits.
The calculated sound pressure level must maintain a margin below the community sound pressure level limit at the same location Additionally, it is essential to consider the reliability of the sound power levels utilized and account for any factors that may have been excluded from the calculation.
Allocating higher sound power level limits to large or high-powered equipment is more cost-effective than applying uniform sound power level limits to all equipment.
When community sound pressure levels surpass acceptable limits, the noise control engineer must evaluate various strategies These may include relocating equipment to increase distance from the community, implementing natural or artificial screening like hills or buildings, utilizing sound barriers, or installing noise-reducing acoustic enclosures.
In most cases, it is better to reduce noise at source.
Sound pressure level limit for equipment
For equipment where no other limit than the work area limit (see 5.1.3) is applicable, the emission sound pressure limits given in 6.3.2 to 6.3.6 shall apply.
Where more or less (e.g restricted area) stringent work area noise limits apply, the equipment noise limits given below shall be adapted accordingly.
Equipment sound pressure level limits shall not be exceeded anywhere at a distance of 1 m from the equipment surface or at the operator position.
In open plant environments, certain equipment may be housed within buildings or shelters It is essential to calculate the sound pressure levels inside these structures by considering both internal equipment noise and external noise sources The assessment of noise attenuation from outside to inside the building should adhere to established acoustic principles.
The maximum value for the equipment noise limit (sound pressure level) shall comply with the work area limit (see 5.1.3).
When equipment comprises multiple components, such as a driver and a driven part, applying limits to each component individually may not guarantee that the overall assembly adheres to the work area noise limits Therefore, it is essential to establish stricter noise limits for each component on the data or requisition sheets The noise limit for each component should be determined through acoustic calculations.
To minimize noise pollution, a stricter equipment noise limit is necessary when multiple pieces of equipment are installed in proximity or in areas with high reverberation This limit should be determined through acoustic calculations, as outlined in ISO/TR 11690-3.
6.3.3 Equipment emitting intermittent or fluctuating noise
When equipment complies with general noise limits 5.1 and 5.2 but produces intermittent or fluctuating noise, such as from depressuring, boiler blow-down, or sump pumps, the estimated equivalent continuous sound level, L eq, must not exceed the specified equipment limits in section 6.3.2 Additionally, end-users or authorities may establish a maximum instantaneous noise level as outlined in clause 5.
NOTE Some regulations require a 5 dB exchange rate for halving the worker exposure instead of the 3 dB exchange rate implicit in the use of an equivalent continuous sound pressure level.
6.3.4 Equipment located outside the work area
The equipment noise limit is typically established at a distance of 1 meter from the source If the closest accessible point exceeds this distance, the noise limit for 1 meter may be adjusted upwards and must be calculated accordingly This situation often arises with vent stacks and specific control valves.
While the increase may be acceptable from a work area perspective, it could violate environmental noise regulations, particularly in cases like flare noise Therefore, the most stringent requirement between the work area limit and the environmental noise limit must be enforced.
6.3.5 Additional restrictions for tonal or impulsive noise
Further restrictions can apply when the noise of an equipment item contains tonal and/or impulsive components and the relevant sound source contributes significantly.
Some additional information on the noise aspects of specific equipment is listed in annex D.
Equipment noise data sheets
Equipment noise data sheets must be created for all relevant equipment or for an equipment train supplied by a single vendor, detailing the limits specified in sections 6.2 and/or 6.3 If the components of the train are sourced from multiple suppliers, individual noise data sheets should be prepared for each component.
Equipment noise limits should be expressed as an overall A-weighted value in decibels Additionally, it may be beneficial to specify the corresponding octave-band spectrum ranging from 63 Hz to 8 kHz.
An equipment noise data sheet, like the model in annex E, is essential for defining sound pressure level limits at a specified distance, typically 1 meter from the equipment surface or operator position, as well as sound power level limits, or both.
The supplier must provide noise guarantees for the equipment, covering all expected operating conditions.
The equipment noise data sheet must include all necessary information for the equipment supplier to understand and adhere to the noise limits for the supplied equipment This International Standard, along with agreements between the end-user and contractor, is not meant to be provided to the equipment supplier.
The equipment noise data sheet must be submitted with the tender, including the supplier's completed guarantee section It should provide unsilenced sound power and sound pressure levels in octave bands, as well as the A-weighted overall levels of the equipment Additionally, it must detail sound power and sound pressure levels in octave bands, along with any necessary silencing measures to comply with specified noise limits If the specified limits cannot be achieved, the minimum attainable sound power and sound pressure levels in octave bands and the A-weighted overall levels should be included Lastly, the sheet must outline any tonal, impulsive, intermittent, or fluctuating noise levels.
Additionally the following information shall be given, where applicable: e) completed data/requisition sheets of any silencers and/or acoustic enclosures, if the tender comprises such silencing equipment.
Data based on measurements shall be determined according to accepted standards International Standards, for instance the ISO 11200-series and ISO 3740-series, are recommended.
All guaranteed noise levels quoted shall include upper measuring tolerances The noise control engineer should consider the test method tolerances when setting the noise limits for individual equipment items.
When guarantees are provided through alternative means, it is unnecessary to specify equipment noise limits on individual data or requisition sheets For instance, if a supplier supplies all pumps or motors for a project, a list of guaranteed noise levels and spectra for each item will suffice.
The sound power level limit and sound pressure level limit are not necessarily connected, as they may arise from distinct general limits Specifically, the sound power limit can be derived from the "environmental" noise limit, while the sound pressure limit may stem from the "work area" noise limit.
NOTE 2 An example of declaring noise emission values of machinery and equipment that includes measuring and production tolerances in this way is given in ISO 4871.
NOTE 3 Octave-band spectra are needed for further acoustic calculations However unless otherwise specified, the overallA-weighted value in decibels will be evaluated against the noise limit.
Equipment selection
(A14) It shall be ensured that suppliers have provided in their tenders all the information required in accordance with 6.4.
If the noise measurement method used by the supplier differs from the method required or recommended on the data sheet, the influence of such a difference shall be evaluated.
Bid comparisons must include the total costs of all options to achieve the specified noise limits When selecting between equipment designed for low noise emission and those requiring external noise abatement measures, it is essential to consider the potential additional operational and maintenance costs associated with path treatment Overall, equipment with inherent low noise emission should be prioritized in the selection process.
For equipment that produces fluctuating or intermittent noise, temporary exceedances of the noise limit may be allowed, as outlined in sections 6.2 and 6.3.3 However, if it is possible to avoid these exceedances by choosing a quieter and equally acceptable alternative, that option should be prioritized If a more expensive solution appears warranted, it is essential to consult the end-user.
Silencing equipment, including silencers and acoustic enclosures, can be part of tenders for noisy process equipment Once a supplier is chosen, the specifics of the silencing equipment should be negotiated between the supplier and the contractor It is beneficial for the equipment supplier to provide silencers to ensure that both the noise source and its control are managed within a single supply scope However, the contractor has the option to procure silencing equipment independently from the process equipment.
Noise emissions from silencing equipment, such as silencers on vent stacks and acoustic insulation on pipes, may not solely be the responsibility of the equipment supplier but rather that of the contractor It is essential to incorporate this silencing equipment into the design and to prepare the necessary data and requisition sheets accordingly.
In the design of spaces with noisy equipment, it is essential to include sound-absorbing materials or constructions to minimize reverberation ISO 11690-1 provides guidelines on the recommended acoustic properties for workrooms to ensure adequate sound absorption.
Certain equipment may show through calculations or measurements that noise limits could be surpassed; however, there exists a margin of uncertainty that suggests levels may actually fall below these limits.
Noise control measures for equipment should be designed proactively, rather than waiting for actual noise levels post-start-up If there is a possibility to delay these measures, this must be explicitly agreed upon with the end-user and approved by governing authorities Additionally, essential services like electrical and instrumentation must be arranged prior to start-up The design must also account for potential consequences of late noise control implementation, such as changes in electrical classification.
For large plants, the cost of downtime or lost production to fit noise control equipment after start-up will often exceed the cost of the noise control equipment itself.
Silencers to suppress noise during the commissioning phase may be of a movable and temporary type.
Silencers to reduce noise in transient operations such as start-up, shutdown, etc., shall be permanent.
When selecting silencers, refer to ISO 14163 for guidance It is crucial that the design of silencers prevents any internal components from becoming dislodged, as this could obstruct the silencer outlet or potentially harm downstream equipment, such as compressors.
Acoustic enclosures, as outlined in ISO 15667, can be categorized into close-fitting and walk-in types It is essential that large enclosures are designed to allow operating and maintenance personnel to perform their tasks without restrictions on movement.
Some authorities require that field-installed noise control measures, such as acoustic insulation, be inspected by a suitably experienced noise control engineer during the installation process.
Noise control documentation
Annex F outlines the necessary documents that the contractor's noise control engineer must provide, which can assist the end-user during the design and procurement stages of a project The level of detailed noise information reported to the end-user will be determined through mutual agreement.
Engineering phase reports
When environmental noise limits or plant sound power limits are established, a noise allocation report must be created to detail the distribution of sound power levels among different equipment This report, which relies on manufacturer data, experience, or databases, is essential for establishing equipment noise limits and planning noise reduction strategies Prior to releasing data or requisition sheets for tendering, the report must be submitted to the end-user for approval.
The contractor is required to submit a noise control report for the end-user's approval after the primary equipment selection is completed This report must include adequate data and calculations to convincingly show that the plant's acoustic design will fulfill the necessary requirements.
(A21) The model formats given in annexes G and H may be used for these reports and the contents shall be agreed between the end-user and contractor.
In both reports (action items A19 and A20), due attention shall be given to the prediction of piping noise (see annex D).
Noise test runs
(A22) The contractor or end-user shall decide which equipment shall have a noise test run at the supplier's works.
Test runs conducted at the supplier's facility may not accurately reflect the actual operating conditions Therefore, it is essential for the end-user, contractor, and supplier to collaboratively determine the necessary adjustments to the tests in order to accurately estimate the equipment's noise levels during service.
Acceptance of individual equipment items is contingent upon successful noise test runs conducted at the supplier's facility These test runs must accurately represent the in-situ arrangement, and a suitable testing procedure should be established in agreement among the contractor, end-user, and supplier.
Acceptance test
At the beginning of the project, the contractor and end-user must establish a mutually agreed-upon procedure for the plant noise acceptance test, which includes the methods for measurement, calculation, and acceptable tolerances, while also taking into account the requirements set by relevant governing authorities.
Surveys may encompass measuring sound pressure levels at designated points within the plant, identifying areas where noise limits surpass specified thresholds and potential hearing protection zones based on a plant tour, assessing worker noise exposure levels, and determining the sound power level of the entire plant or specific sections using ISO 8297, along with the resulting sound pressure levels at community locations.
Accordingly the format of the model noise verification report may need to be varied in line with the project requirements.
A final plant acceptance test must be conducted and documented in a noise verification report by the end-user, contractor, or an independent party, following the agreed test procedures from action item A23 Additionally, certain authorities may mandate the involvement of certified or accredited organizations in this process.
The verification report, prepared according to the format in annex I, typically includes a noise survey of the plant This survey's results are compared with the project's requirements, and the comparison of the required and measured noise levels finalizes the verification process.
The model noise verification report serves as a comprehensive framework for conducting a standard plant noise survey and verification It also acts as a helpful checklist for essential elements to document during the noise survey process.
A noise survey conducted prior to the commencement of a project is essential for establishing baseline noise conditions on site, often referred to as zero measurement Subsequent noise surveys, performed after the project's start-up, are crucial for ensuring compliance with the established noise limits.
The model noise survey report does not focus on measuring the sound pressure levels of individual equipment or deriving their sound power levels Although these activities may be included in a verification report, detailed descriptions of such noise measurements can be found in other applicable International Standards.
Remedial action
If the actual sound pressure or power levels exceed the specified limits during acceptance testing, corrective action must be implemented The contract between the end-user and the contractor will outline the responsibility for rectification Compliance with the specifications will be verified following the corrective measures.
informative) Example of format for the Noise Verification Report
NOTE Numbers A1, A2, etc refer to action items, see annex B.
Summary of action items and allocation of responsibility
The action items defined in this International Standard are summarized in Table B.1; the allocation of the responsible party should be agreed before the start of a project.
Note that the action items given in Table B.1 are not in the chronological order in which they occur in a project.
Task description Reference clause end-user contractor A1 Investigate applicable regulations for in-plant noise 5.1.1 x
A2 State in-plant noise limits in project specification 5.1.1 x
A3 Obtain end-user's permission for restricted areas; set limits for those areas
A4 Erect signs indicating hearing protection zones 5.1.4 x
A5 Investigate applicable regulations on environmental noise and discuss the interpretation with authorities
A6 Consider environmental noise aspect (where no regulations exist or are considered insufficient)
A7 Incorporate sound power limit in project specification 5.2 x
A8 Set noise limits for occasional operating conditions, viz. start-up, shutdown, maintenance and emergencies
A9 Set special noise limits during plant construction 5.3 x
A10 Specify equipment noise limits, including additional restrictions
A11 Determine pipe noise; assess insulation and silencer requirements
A12 Determine the need for vent silencers D.4 x
A13 Evaluate the need for special requirements for flare D.5 x
A14 Obtain noise limitation sheet with guaranteed power/ pressure level from supplier, incl silencers/enclosures
A16 Agree on details of silencers/enclosures 7 (x) x
A17 Agree on postponing the decision to apply noise control measures until after start-up
A18 Prepare noise control (background) information 8.1 (x) x
A21 Agree format for noise control reports 8.2 x x
A22 Decide which equipment shall have a noise test run 8.3 x
A23 Agree on acceptance test procedure 8.4 x x
A24 Perform final plant acceptance test – Noise verification report
A25 Take corrective action where required 8.5 x a Indicated responsibilities are given as an example, they can deviate from project to project.
Information for inclusion in Project Specification
The Project Specification must clearly define responsibilities related to noise control, including establishing noise limits and requirements, detailing end-user specifications for noise-control engineering, and outlining specific equipment noise limits along with calculation and measurement procedures It should specify the end-user's role in reviewing contractor methodologies and noise prediction models, as well as the practicality and maintenance of noise-control measures Additionally, responsibilities for creating a noise measurement protocol, defining operating conditions for verification, and conducting necessary measurements to ensure compliance with noise limits must be included Finally, the extent of the end-user's monitoring and inspection of noise control measures during installation should also be addressed.
Noise aspects of specific equipment
For each control valve and its associated pipe work, the requirements of 6.3.2 to 6.3.5 should apply.
Control valve noise should be determined for three operating conditions, viz minimum, normal and maximum throughput Noise limits should not be exceeded for any of these three conditions.
The noise from safety/relief valves (and their piping) which blow under emergency conditions only, should not exceed the absolute limit (see 5.1.2) in any work area.
Noise generated by piping is crucial for effective plant noise control and must adhere to the same regulations as equipment This type of noise typically originates from components like valves or compressors.
Predicting noise from piping is a challenging task typically handled by contractors The noise emitted from structures that support piping can be considerable, particularly in the case of acoustically insulated piping Relevant references, such as VDI 3733, are available in the Bibliography for further guidance.
To effectively manage noise levels, it is essential to choose low-noise equipment or, if that is not feasible, to implement in-line silencers or acoustic insulation ISO 15665 provides guidance on assessing and reducing noise from piping through acoustic insulation Additionally, incorporating in-line silencers in the suction line of compressors typically necessitates approval from the end-user.
All vents designed to meet operational requirements must adhere to the same restrictions as the equipment If needed, vent or blow-down silencers should be included in the design Additionally, vents designated for emergency use must comply with the same standards as safety and relief valves.
NOTE An acceptable method of calculating vent noise is given in API RP 521, see Bibliography.
D.5.1 (A13) Elevated flares under emergency conditions
The noise level at the base of the stack should not exceed the absolute limit (see 5.1.2).
If the plant to which the flare is allocated is subject to environmental noise requirements, the noise levels produced during emergency conditions should be evaluated against authority requirements.
D.5.2 (A13) Elevated flares under normal operating conditions (including start-up and shutdown)
Noise levels at the boundary of the safety zone, which is at least 60 meters from the flare base, must not surpass the work area limit when operating at flow rates up to 15% of the maximum flaring capacity or at the highest relief rate during normal operations, including start-up and shutdown, whichever is greater.
If there are environmental noise limits, then the sound power level generated during normal operation should be taken into account when assigning sound power levels to noise sources (see 6.2).
Ground flares should not exceed the work area limit outside the windscreen or louvre wall.
Example of equipment noise data sheet
Type of equipment: Mechanical power (kW):
This data sheet covers the noise limits of the equipment, given below.
2 NOISE LIMITS TO BE MET BY THE EQUIPMENT
The equipment must operate within the specified noise limits outlined in the table below, ensuring that noise levels do not exceed the stricter criteria under any normal operating conditions.
L p is the maximum sound pressure level, re 20 m Pa in dB, for the mode of operation indicated at any location at 1 m from the equipment surface or operator position, if specified.
L W is the maximum sound power level, ref 1 pW, in dB, for the mode of operation indicated.
If the equipment generates noise with tonal or impulsive components, this shall be indicated.
Noise levels will be verified according to the following standards: ISO 3740 series, ISO 11200 series, ISO 9614 or International
Standards or methods required or recommended by the authorities.
3 INFORMATION TO BE SUBMITTED WITH THE TENDER
This noise data sheet shall be returned with the tender and with guaranteed noise data filled in.
The supplier shall state which add-on silencing measures were taken to meet the noise requirements.
Equipment items/Locations a Sound pressure/power levels guaranteed by supplier dB b Remarks
Un-weighted octave-band levels 63
Purchaser shall indicate: in column “b”, the A-weighted sound pressure/power limit in column “a” using the appropriate number, which of the following applies to the required noise levels:
4) suppliers best estimate, not necessarily guaranteed
Information on special operating conditions:
Documents to be made available to the noise control engineers
For major design and engineering projects, it is essential to submit specific documents to the noise control engineer as they become available These include the project specification, site layout drawing, local area plan, basis of plant design, process flow diagram, equipment list, and a comprehensive process description detailing all operational modes Additionally, equipment data requisitions for various noise sources such as air-cooler fans, furnaces, mechanical handling equipment, pumps, and mobile noise sources must be provided In special cases, data on the acoustic properties of buildings, along with piping arrangement data and piping and instrumentation diagrams, should also be included.
Example of format for the Noise Allocation Report
The report outlined in section 8.2, designated as action item A19, should adhere to a specific format that includes the original requirements along with any necessary comments, as well as a comprehensive list of equipment items such as valves, piping, and buildings, detailing relevant information for each.
2) short description (e.g centrifugal pump, recip compressor )
3) typical description of duty (e.g 3 000 r/min, 150 kW)
4) allocated sound pressure level in decibels, A-weighted
5) allocated sound power level in decibels, A-weighted
6) total allocated sound power level per plant unit in decibels, A-weighted
7) total allocated sound power level for project in decibels, A-weighted c) Description of anticipated restricted areas d) Indication of areas of maximum uncertainty of noise data
Example of format for the Noise Control Report
The report specified in 8.2 and nominated as action item A20 may be prepared in accordance with the following format.
1 Summary showing to what extent ã the acoustic design of the plant has been completed ă ã guaranteed noise data has been obtained from suppliers ă ã the specified noise limits have been met ă
2 Specified limits — quote the original requirements and make any comments necessary ¨
Supplier noise data includes tables of octave-band sound power, sound pressure, and overall noise levels for all potentially noisy equipment within each plant unit The source of this data must be specified, whether it is a guarantee from the supplier, an estimate from the supplier, test data from the contractor, or an estimate from the contractor Additionally, the results of any available "noise" test runs should be included.
4 Noise control measures ã a list of silencers and acoustic enclosures ă ã the detail and extent of any acoustic insulation ă
The article discusses the creation of in-plant noise contour maps that illustrate A-weighted sound pressure level contours, such as 75 dB, 80 dB, and 85 dB It includes the evaluation of the sound power level of the plant or its sections, even when no specific sound power limit is mandated Additionally, it addresses immission noise levels at specific points and presents environmental noise contour maps that display A-weighted sound pressure level contours The article also emphasizes the separate evaluation of plant pipe noise and the calculations of expected sound pressure levels within buildings and shelters.
A comprehensive list of control valves exhibiting an A-weighted sound pressure level exceeding 80 dB is provided, along with indications of where low-noise control valves or alternative noise reduction measures will be implemented.
Example of format for the Noise Verification Report
The report specified in 8.4 and nominated as action item A24 may be prepared in accordance with the following format.
1 The objective of the noise verification report ¨
2 The survey or calculation methods to be used (i.e refs [11], [30], [32], [33]) In some countries the environmental authorities have supplementary or different requirements for noise verification reports. ¨
3 The name of the end-user, the name and location of the plant ¨
4 The date and time of the noise survey ¨
5 The names and/or affiliations of the personnel participating in the noise survey ¨
6 The noise limits set for the project ¨
7 A map or drawing of the area to be surveyed a ¨
8 A description of the plant and a description of the type of noise being generated ¨
9 The plant operating conditions at the time of survey, including production configuration, percent throughput, whether in normal operation, abnormal operation, start-up or shutdown mode. ¨
10 The weather conditions at the time of the measurements (if relevant), in particular wind speed and direction, relative humidity and air temperature. ¨
11 The type, model, serial number and calibration and method of calibration of all instrumentation used b ¨
12 Operator work patterns where noise exposure per shift is required to be verified ¨
13 Sound pressure measurements and octave band levels recorded at agreed immission points The bottom octave band will usually be 63 Hz. ¨
14 Report on any locations at which measurements could not be taken or omitted for other reasons. ¨
15 A qualitative but brief assessment of neighbouring noise sources (other plants, road noise, etc.) likely to affect the measured sound pressure readings. ¨
16 Report the corrections for background noise, if any, and microphone positions at which the background noise could not be measured. ¨
17 The calculated plant A-weighted sound power levels per octave band and A-weighted overall sound power level. ¨
18 Report any deviations from the survey requirements due to the site environment ¨
19 Prepare environmental noise contour maps ¨
20 Preparation of an in-plant noise contour plot, showing A-weighted contours of for instance
75 dB and higher, with incremental steps of 5 dB. ¨
21 Compare the noise survey results with the requirements ¨
22 Identify whether any of the project requirements are exceeded (if at all) ¨
23 Identify causes for the noise requirements being exceeded in any location, if possible ¨
24 Octave-band measurements The height of the microphone position should be reported c ¨
25 Corrections made for background noise ¨
For community noise verification, it is essential to provide a map or drawing of the area of concern, indicating all measurement locations and any external noise sources that may impact these locations If a noise contour map is necessary, ensure adequate measurement points are included Additionally, significant noise screens or reflectors on the plant should be described Instrument calibration must be verified at both the start and end of the noise survey When determining sound power levels according to ISO 8297, elevated measurement positions are required, although practical limitations may affect microphone height.
[1] ISO 131, Acoustics — Expression of physical and subjective magnitudes of sound or noise in air
[2] ISO 1999, Acoustics — Determination of occupational noise exposure and estimation of noise-induced hearing impairment
[3] ISO 3740, Acoustics — Determination of sound power levels of noise sources — Guidelines for the use of basic standards
[4] ISO 3741, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Precision methods for reverberation rooms
[5] ISO 3743-1, Acoustics — Determination of sound power levels of noise sources — Engineering methods for small, movable sources in reverberant fields — Part 1: Comparison method for hard-walled test rooms
[6] ISO 3743-2, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Engineering methods for small, movable sources in reverberant fields — Part 2: Methods for special reverberation test rooms
[7] ISO 3744, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Engineering method in an essentially free field over a reflecting plane
[8] ISO 3745, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Precision methods for anechoic and semi-anechoic rooms
[9] ISO 3746, Acoustics — Determination of sound power levels of noise sources using sound pressure —
Survey method using an enveloping measurement surface over a reflecting plane
[10] ISO 3747, Acoustics — Determination of sound power levels of noise sources using sound pressure —
[11] ISO 4871, Acoustics — Declaration and verification of noise emission values of machinery and equipment
[12] ISO 8297, Acoustics — Determination of sound power levels of multisource industrial plants for evaluation of sound pressure levels in the environment — Engineering method
[13] ISO 9613-1, Acoustics — Attenuation of sound during propagation outdoors — Part 1: Calculation of absorption of sound by the atmosphere
[14] ISO 9613-2, Acoustics — Attenuation of sound during propagation outdoors — Part 2: General method of calculation
[15] ISO 9614-1, Acoustics — Determination of sound power levels of noise sources using sound intensity —
Part 1: Measurement at discrete points
[16] ISO 9614-2, Acoustics — Determination of sound power levels of noise sources using sound intensity —
[17] ISO 9921-1, Ergonomic assessment of speech communication — Part 1: Speech interference level and communication distances for persons with normal hearing capacity in direct communication (SIL method)
ISO 11200 provides guidelines for measuring noise emitted by machinery and equipment, focusing on the determination of emission sound pressure levels at workstations and other specified locations This standard is essential for ensuring compliance with noise regulations and improving workplace acoustics.
ISO 11201 outlines the engineering method for measuring emission sound pressure levels from machinery and equipment at workstations and other designated locations This standard focuses on assessments conducted in an essentially free field over a reflecting plane, ensuring accurate noise evaluation in various environments.
[20] ISO 11202, Acoustics — Noise emitted by machinery and equipment — Measurement of emission sound pressure levels at a work station and at other specified positions — Survey method in situ
[21] ISO 11203, Acoustics — Noise emitted by machinery and equipment — Determination of emission sound pressure levels at a work station and at other specified positions from the sound power level
[22] ISO 11204, Acoustics — Noise emitted by machinery and equipment — Measurement of emission sound pressure levels at a work station and at other specified positions — Method requiring environmental corrections
[23] ISO 11690-1, Acoustics — Recommended practice for the design of low-noise workplaces containing machinery — Part 1: Noise control strategies
[24] ISO 11690-2, Acoustics — Recommended practice for the design of low-noise workplaces containing machinery — Part 2: Noise control measures
[25] ISO/TR 11690-3, Acoustics — Recommended practice for the design of low-noise workplaces containing machinery — Part 3: Sound propagation and noise prediction in workrooms
[26] ISO 12001:1996, Acoustics — Noise emitted by machinery and equipment — Rules for the drafting and presentation of a noise test code
[27] ISO 14163, Acoustics — Guidelines for noise control by silencers
[28] ISO 15665, Acoustics — Acoustic insulation for pipes, valves and flanges
[29] ISO 15667, Acoustics — Guidelines for noise control by enclosures and cabins
[30] API RP 521, Guide for Pressure Relief and Depressuring Systems (American Petroleum Institute, Washington DC, USA)
[31] EEMUA 140, Noise Procedure specification, The Engineering Equipment and Materials Users Association
[32] VDI 3733, Noise at pipes (Verein Deutscher Ingenieure)
[33] IL-HR-13-01:1981, Guide for measuring and calculating industrial noise (in Dutch) Ministerie van Volksgezondheid en Milieuhygiene, The Netherlands
[34] Guidelines from the Danish Environmental Protection Agency, No 5/1993: Calculation for environmental noise from industry (in Danish), Denmark, 1993
[35] Beranek, L.L and Vér, I.L Noise and vibration control engineering, principles and application Wiley Interscience, 1992 (ISBN 0-471-61751-2)
[36] Bies, D.A and Hansen, C.H Engineering Noise Control, Theory and practice 2 nd edn Unwin Hyman,
[37] Danish Acoustical Laboratory, Report No 32 Environmental noise from industrial plants: General prediction method Lyngby, Denmark, 1983
[38] Heckl, M and Müller Taschenbuch der Technischen Akustik 2 nd edn Springer Verlag, 1994 (ISBN 3-540-54473-9)