E33.08 - Mechanical and Electrical System Noise

SIGNIFICANCE AND USE
5.1 This standard defines measurement procedures for estimating the risk of noise-induced hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and mobile, transportable, and stationary equipment. The primary approach is to separately measure the sound level at operator ear locations for each normal operating condition. These levels can be combined with operational use scenarios and exposure criteria to define noise exposure severity. The data can also be used to define hearing protection requirements or administrative controls to preclude hearing hazards.  
5.2 The practice has the following limitations:  
5.2.1 The practice uses field portable measurement equipment.  
5.2.2 The practice produces data which may be compared with applicable criteria or limits if the limits are in terms of the quantities measured in this standard or which can be calculated from the measured data.
SCOPE
1.1 This standard defines noise measurement procedures for estimating the risk of hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and other mobile, transportable, or stationary equipment.  
1.2 This standard does not recommend noise exposure limit levels or criteria for any application discussed.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 This is an in situ method, that is, the measurements are made at the actual installation. The sound levels measured according to this test method should be representative for that installation and for the quantity of acoustical absorption actually, permanently present.  
5.2 The test method has the following limitations:  
5.2.1 The test method produces sound data which may be compared with applicable criteria or limits only if they are in terms of the quantities measured in this test method.  
5.2.2 The test method does not quantify certain subjective aspects of the sound environment that may be objectionable. These include pure tones, spectral content, and temporal distribution.
SCOPE
1.1 This test method provides guidance to the methodology used in the measurement of building interior sound levels.  
1.2 This test method describes procedures for measuring sound in enclosed residential spaces produced by built-in utilities and major appliances such as plumbing, heating, ventilating, air-conditioning systems, refrigerators, and dish washers. The measured values may then be used to assess compliance, design, or habitation suitability.  
1.3 This test method does not promulgate or recommend acoustical criteria.  
1.4 This test method is not intended for obtaining data to evaluate indoor environments for:  
1.4.1 Commercial activities such as studios, communication centers, hospitals, and auditoria, and  
1.4.2 Effects from exterior sources such as aircraft, railroad operations, motor vehicles, mining operation, weapons fire, etc.  
1.5 This test method is not intended for evaluating sound transmission loss, sound absorption coefficient, or any other acoustical aspects of the space or structure.  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 The insertion loss of a pipe lagging system depends upon the lagging system materials, the method used to apply the materials, the pipe wall thickness, the size and shape of the bare and lagged pipe, and the mechanisms causing noise radiation from the pipe. Insertion losses measured using this test method should be used with some caution. In the laboratory, measurements must be made under reproducible conditions, but in practical usage in the field, the conditions that determine the effective insertion loss are difficult to predict and they may lead to slightly different results. Insertion losses measured with this test method can be used successfully for acoustical design purposes. Insertion losses measured with this test method are most useful for pipes and lagging systems which are similar to those used in the laboratory configuration.  
5.2 This test method may be used to rank-order pipe lagging systems according to insertion loss or to estimate the field insertion loss of pipe lagging systems installed in the field.  
5.3 This test method assumes that pipe wall stresses resulting from different methods of supporting the test pipe in the laboratory do not have a significant effect upon the measured insertion loss.  
5.4 Pipe lagging systems typically have small insertion loss, and sometimes negative insertion loss, at frequencies below 500 Hz. The results obtained at frequencies below 500 Hz may be somewhat erratic. Sound sources used with this test method normally have a low frequency limit in the range from 300 to 500 Hz. For these reasons, the lowest band of frequencies for which results are required is centered at 500 Hz.
SCOPE
1.1 This test method covers the measurement of the insertion loss of pipe lagging systems under laboratory conditions.  
1.2 A procedure for accrediting a laboratory for purposes of this test method is given in Annex A1.  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 This test method permits the evaluation of both the acoustical and mechanical performance of pneumatic exhaust silencers designed for quieting compressed gas exhausts (usually air). The data can be used by manufacturers to assess or improve their products, or by users to select or specify a silencer. The data acquired using this measurement method allow for performance comparisons of competitive products and aid in the selection of an appropriate device.  
5.2 Flow rate is an important parameter to consider when the application involves machinery or equipment that requires compressed air or other gases to be exhausted rapidly. For example, in an automatic pneumatic press, compressed air must be exhausted rapidly to avoid a premature second cycle. For this reason, flow ratio is reported in addition to acoustical performance.
SCOPE
1.1 This test method covers the laboratory measurement of both the acoustical and mechanical performance of pneumatic exhaust silencers designed for quieting compressed gas (usually air) exhausts from orifices connected to pipe sizes up to 3/4 in. NPT. This test method is not applicable for exhausts performing useful work, such as part conveying, ejection, or cleaning. This test method evaluates acoustical performance using A-weighted sound level measurements.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 Specimens tested using this standard, for example, duct silencers, are used to control sound propagation through ventilation ducts. The results gathered from testing specimens to this standard can be used to estimate the reduction in fan sound levels in ducted airflow systems caused by including a sound attenuating device in the system. The device can be a component in a source-path-receiver analysis where calculations are performed to determine the resultant sound level in an occupied space. Correct selection of a sound attenuating device can enable a designer to achieve in-space background noise criteria.  
5.2 The insertion loss of a silencer varies with frequency and with the direction and speed of airflow. Because silencers partially obstruct the air path and provide resistance to airflow, two other effects must be quantified: pressure drop and airflow-generated noise. Both increase with increasing air speeds; thus data are required for several airflows to correctly characterize performance.  
5.3 The aerodynamic results from testing specimens to the standard can be used as information for the system design engineer to determine the amount of static pressure drop resistance to be overcome by the system fan(s). Guidelines for appropriate maximum allowable pressure drop for a sound attenuating element have been established in the design community and are based on the procedures described herein.  
5.4 As stated previously in 1.4 of this test method, the actual performance of a sound attenuating device as installed in an air duct system may be significantly different than reported based on the test procedure herein. This standard does not provide guidance to the user on these system effects.  
5.5 Silencers are often designed to be used under conditions which do not duplicate the test set-ups of this standard. Mock-ups and specialized test set-ups to determine performance of sound attenuating devices in non-standard configurations may be based on this test...
SCOPE
1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.  
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.  
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.  
1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen under field conditions.  
1.5 The values stated in SI units are to be regarded as standard. The values in parentheses are provided for information only.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE
5.1 All noise control features associated with the inlet or exhaust of large industrial fans and gas turbines are, or should be, based upon inlet or exhaust sound power levels in octave bands of frequency. Sound power levels are not directly measurable, however, so they must be calculated indirectly, using estimated or measured duct interior sound pressure levels.  
5.2 Estimated in-duct sound pressure level may be obtained by measuring exterior airborne sound pressure levels and applying a transfer function representing the transmission loss of the duct wall. Significant uncertainties are associated with such a procedure, suggesting the need for this guide.  
5.3 Estimated in-duct sound pressure level may be obtained by measuring exit plane sound pressure levels and applying a transfer function consisting of the insertion loss through the gas path, including the insertion loss of any silencers. Significant uncertainties are associated with such a procedure, suggesting the need for this guide.  
5.4 This guide purports to measure the in-duct sound pressure level directly using type 1 instrumentation per ANSI S1.4 or S1.43. It is limited, however, to the determination of the sound pressure level at the location of the port only and will include the effects of duct acoustical modes, as well as an unknown degree of turbulence and other flow related effects. Methodologies may be devised by the user to minimize such effects. As a rule, the larger the number of test ports used, the better will be the averaged data. Although not prescribed by this guide, cross-channel coherence analysis is also available to the analyst, using ports at different locations along the duct axis, which may yield improvements in data quality.  
5.5 This guide is intended for application to equipment in-situ, to be applied to large fans and gas turbines having inlet or exhaust ducts whose cross sectional areas are approximately four (4) square meters, or more, and are therefore not amenable t...
SCOPE
1.1 This guide is intended to provide a simple and consistent procedure for the in-situ field measurement of in-duct sound pressure levels in large low pressure industrial air ducts, such as for gas turbines or fans, where considerations such as flow velocity, turbulence or temperature prevent the insertion of sound pressure sensors directly into the flow. This standard guide is intended for both ambient temperature intake air and hot exhaust gas flow in ducts having cross sections of four (4) square meters, or more.  
1.2 The described procedure is intended to provide a repeatable and reproducible measure of the in-duct dynamic pressure level at the inlet or exhaust of the gas turbine, or fan. The guide is not intended to quantify the “true” sound pressure level or sound power level. Silencers, as well as Waste Heat Boilers, must be designed using the in-duct sound power level as the basis. Developing the true sound power level based on in-duct measurements of true sound pressure within a complete operating system is complex and procedures are developmental and often proprietary.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Extreme caution is mandatory when working near hot exhaust gas systems and appropriate safety precautions such as the installation of quick acting isolation valves are recommended.

SIGNIFICANCE AND USE
5.1 The function and operation of equipment in the field often preclude the measurement of the free-field sound pressure levels of a single piece of equipment in the absence of interfering sound from other equipment operating at the same time. The two-surface method will provide, in most cases, a reliable estimate of the normal sound power levels of a specimen operating in an adverse environment.  
5.2 This test method is intended for use in the field in the presence of what is normally regarded as interfering background noise. This test method is based upon the work of Hubner 5,6 and Diehl,7 but differs from all other current sound power measurement procedures by requiring simultaneous measurement at both conformal surfaces and by resolving time-averaged sound pressure levels at both surfaces to within 0.1 dB. These two features, simultaneous recording and 0.1dB resolution, enable source sound power to be calculated when the direct sound field of the source is actually lower in level than the ambient noise.  
5.3 The use of this test method is expected to be primarily for the relative assessment of the sound power from similar sources or for the prediction of sound levels in a plant based upon measurements of similar sources in another plant. This test method is believed to be capable of yielding a reasonably good estimate of absolute power level with proper care of application and full conformance to the provisions of this procedure.  
5.4 The two-surface method is applicable only when the two measurement surfaces can be physically selected to produce positive values of the difference in average sound pressure level. That is, the inner surface sound pressure level minus the outer surface sound pressure level must be at least +0.1 dB. This limitation applies to each frequency band and each constituent surface area investigated. Only the frequency band in which a zero or negative difference occurs is it considered invalid and usually adjacent bands will be valid....
SCOPE
1.1 This test method covers the field, or in situ measurement of sound power level by the two-surface method. The test method is designed to minimize the effects of reverberant conditions, directivity of the noise source under consideration, and the effects of ambient noise from other nearby equipment operating at the same time.  
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 The insertion loss of a pipe lagging system depends upon the lagging system materials, the method used to apply the materials, the pipe wall thickness, the size and shape of the bare and lagged pipe, and the mechanisms causing noise radiation from the pipe. Insertion losses measured using this test method should be used with some caution. In the laboratory, measurements must be made under reproducible conditions, but in practical usage in the field, the conditions that determine the effective insertion loss are difficult to predict and they may lead to slightly different results. Insertion losses measured with this test method can be used successfully for acoustical design purposes. Insertion losses measured with this test method are most useful for pipes and lagging systems which are similar to those used in the laboratory configuration.  
5.2 This test method may be used to rank-order pipe lagging systems according to insertion loss or to estimate the field insertion loss of pipe lagging systems installed in the field.  
5.3 This test method assumes that pipe wall stresses resulting from different methods of supporting the test pipe in the laboratory do not have a significant effect upon the measured insertion loss.  
5.4 Pipe lagging systems typically have small insertion loss, and sometimes negative insertion loss, at frequencies below 500 Hz. The results obtained at frequencies below 500 Hz may be somewhat erratic. Sound sources used with this test method normally have a low frequency limit in the range from 300 to 500 Hz. For these reasons, the lowest band of frequencies for which results are required is centered at 500 Hz.
SCOPE
1.1 This test method covers the measurement of the insertion loss of pipe lagging systems under laboratory conditions.  
1.2 A procedure for accrediting a laboratory for purposes of this test method is given in Annex A1.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 This standard defines measurement procedures for estimating the risk of noise-induced hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and mobile, transportable, and stationary equipment. The primary approach is to separately measure the sound level at operator ear locations for each normal operating condition. These levels can be combined with operational use scenarios and exposure criteria to define noise exposure severity. The data can also be used to define hearing protection requirements or administrative controls to preclude hearing hazard.  
5.2 The practice has the following limitations:  
5.2.1 The practice uses field portable measurement equipment.  
5.2.2 The practice produces data which may be compared with applicable criteria or limits if the limits are in terms of the quantities measured in this standard or which can be calculated from the measured data.
SCOPE
1.1 This standard defines noise measurement procedures for estimating the risk of hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and other mobile, transportable, or stationary equipment.  
1.2 This standard does not recommend noise exposure limit levels or criteria for any application discussed.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 This is an in situ method, that is, the measurements are made at the actual installation. The sound levels measured according to this test method should be representative for that installation and for the quantity of acoustical absorption actually, permanently present.  
5.2 The test method has the following limitations:  
5.2.1 The test method produces sound data which may be compared with applicable criteria or limits only if they are in terms of the quantities measured in this test method.  
5.2.2 The test method does not quantify certain subjective aspects of the sound environment that may be objectionable. These include pure tones, spectral content, and temporal distribution.
SCOPE
1.1 This test method provides guidance to the methodology used in the measurement of building interior sound levels.  
1.2 This test method describes procedures for measuring sound in enclosed residential spaces produced by built-in utilities and major appliances such as plumbing, heating, ventilating, air-conditioning systems, refrigerators, and dish washers. The measured values may then be used to assess compliance, design, or habitation suitability.  
1.3 This test method does not promulgate or recommend acoustical criteria.  
1.4 This test method is not intended for obtaining data to evaluate indoor environments for:  
1.4.1 Commercial activities such as studios, communication centers, hospitals, and auditoria, and  
1.4.2 Effects from exterior sources such as aircraft, railroad operations, motor vehicles, mining operation, weapons fire, etc.  
1.5 This test method is not intended for evaluating sound transmission loss, sound absorption coefficient, or any other acoustical aspects of the space or structure.  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 Specimens tested using this standard, for example, duct silencers, are used to control sound propagation through ventilation ducts. The results gathered from testing specimens to this standard can be used to estimate the reduction in fan sound levels in ducted airflow systems caused by including a sound attenuating device in the system. The device can be a component in a source-path-receiver analysis where calculations are performed to determine the resultant sound level in an occupied space. Correct selection of a sound attenuating device can enable a designer to achieve in-space background noise criteria.  
5.2 The insertion loss of a silencer varies with frequency and with the direction and speed of airflow. Because silencers partially obstruct the air path and provide resistance to airflow, two other effects must be quantified: pressure drop and airflow-generated noise. Both increase with increasing air speeds; thus data are required for several airflows to correctly characterize performance.  
5.3 The aerodynamic results from testing specimens to the standard can be used as information for the system design engineer to determine the amount of static pressure drop resistance to be overcome by the system fan(s). Guidelines for appropriate maximum allowable pressure drop for a sound attenuating element have been established in the design community and are based on the procedures described herein.  
5.4 As stated previously in 1.4 of this test method, the actual performance of a sound attenuating device as installed in an air duct system may be significantly different than reported based on the test procedure herein. This standard does not provide guidance to the user on these system effects.  
5.5 Silencers are often designed to be used under conditions which do not duplicate the test set-ups of this standard. Mock-ups and specialized test set-ups to determine performance of sound attenuating devices in non-standard configurations may be based on this test...
SCOPE
1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.  
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.  
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.  
1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen under field conditions.  
1.5 The values stated in SI units are to be regarded as standard. The values in parentheses are provided for information only.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 Specimens tested using this standard, for example, duct silencers, are used to control sound propagation through ventilation ducts. The results gathered from testing specimens to this standard can be used to estimate the reduction in fan sound levels in ducted airflow systems caused by including a sound attenuating device in the system. The device can be a component in a source-path-receiver analysis where calculations are performed to determine the resultant sound level in an occupied space. Correct selection of a sound attenuating device can enable a designer to achieve in-space background noise criteria.  
5.2 The insertion loss of a silencer varies with frequency and with the direction and speed of airflow. Because silencers partially obstruct the air path and provide resistance to airflow, two other effects must be quantified: pressure drop and airflow-generated noise. Both increase with increasing air speeds; thus data are required for several airflows to correctly characterize performance.  
5.3 The aerodynamic results from testing specimens to the standard can be used as information for the system design engineer to determine the amount of static pressure drop resistance to be overcome by the system fan(s). Guidelines for appropriate maximum allowable pressure drop for a sound attenuating element have been established in the design community and are based on the procedures described herein.  
5.4 As stated previously in 1.4 of this test method, the actual performance of a sound attenuating device as installed in an air duct system may be significantly different than reported based on the test procedure herein. This standard does not provide guidance to the user on these system effects.  
5.5 Silencers are often designed to be used under conditions which do not duplicate the test set-ups of this standard. Mock-ups and specialized test set-ups to determine performance of sound attenuating devices in non-standard configurations may be based on this test...
SCOPE
1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.  
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.  
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.  
1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen under field conditions.  
1.5 The values stated in SI units are to be regarded as standard. The values in parentheses are provided for information only.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
5.1 This test method permits the evaluation of both the acoustical and mechanical performance of pneumatic exhaust silencers designed for quieting compressed gas exhausts (usually air). The data can be used by manufacturers to assess or improve their products, or by users to select or specify a silencer. The data acquired using this measurement method allow for performance comparisons of competitive products and aid in the selection of an appropriate device.  
5.2 Flow rate is an important parameter to consider when the application involves machinery or equipment that requires compressed air or other gases to be exhausted rapidly. For example, in an automatic pneumatic press, compressed air must be exhausted rapidly to avoid a premature second cycle. For this reason, flow ratio is reported in addition to acoustical performance.
SCOPE
1.1 This test method covers the laboratory measurement of both the acoustical and mechanical performance of pneumatic exhaust silencers designed for quieting compressed gas (usually air) exhausts from orifices connected to pipe sizes up to 3/4 in. NPT. This test method is not applicable for exhausts performing useful work, such as part conveying, ejection, or cleaning. This test method evaluates acoustical performance using A-weighted sound level measurements.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.

SIGNIFICANCE AND USE
All noise control features associated with the inlet or exhaust of large industrial fans and gas turbines are, or should be, based upon inlet or exhaust sound power levels in octave bands of frequency. Sound power levels are not directly measurable, however, so they must be calculated indirectly, using estimated or measured duct interior sound pressure levels.
Estimated in-duct sound pressure level may be obtained by measuring exterior airborne sound pressure levels and applying a transfer function representing the transmission loss of the duct wall. Significant uncertainties are associated with such a procedure, suggesting the need for this guide.
Estimated in-duct sound pressure level may be obtained by measuring exit plane sound pressure levels and applying a transfer function consisting of the insertion loss through the gas path, including the insertion loss of any silencers. Significant uncertainties are associated with such a procedure, suggesting the need for this guide.
This guide purports to measure the in-duct sound pressure level directly using type 1 instrumentation per ANSI S1.4 or S1.43. It is limited, however, to the determination of the sound pressure level at the location of the port only and will include the effects of duct acoustical modes, as well as an unknown degree of turbulence and other flow related effects. Methodologies may be devised by the user to minimize such effects. As a rule, the larger the number of test ports used, the better will be the averaged data. Although not prescribed by this guide, cross-channel coherence analysis is also available to the analyst, using ports at different locations along the duct axis, which may yield improvements in data quality.
This guide is intended for application to equipment in-situ, to be applied to large fans and gas turbines having inlet or exhaust ducts whose cross sectional areas are approximately four (4) square meters, or more, and are therefore not amenable to laboratory testing. Al...
SCOPE
1.1 This guide is intended to provide a simple and consistent procedure for the in-situ field measurement of in-duct sound pressure levels in large low pressure industrial air ducts, such as for gas turbines or fans, where considerations such as flow velocity, turbulence or temperature prevent the insertion of sound pressure sensors directly into the flow. This standard guide is intended for both ambient temperature intake air and hot exhaust gas flow in ducts having cross sections of four (4) square meters, or more.
1.2 The described procedure is intended to provide a repeatable and reproducible measure of the in-duct dynamic pressure level at the inlet or exhaust of the gas turbine, or fan. The guide is not intended to quantify the “true” sound pressure level or sound power level. Silencers, as well as Waste Heat Boilers, must be designed using the in-duct sound power level as the basis. Developing the true sound power level based on in-duct measurements of true sound pressure within a complete operating system is complex and procedures are developmental and often proprietary.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Extreme caution is mandatory when working near hot exhaust gas systems and appropriate safety precautions such as the installation of quick acting isolation valves are recommended.

SIGNIFICANCE AND USE
The function and operation of equipment in the field often preclude the measurement of the free-field sound pressure levels of a single piece of equipment in the absence of interfering sound from other equipment operating at the same time. The two-surface method will provide, in most cases, a reliable estimate of the normal sound power levels of a specimen operating in an adverse environment.
This test method is intended for use in the field in the presence of what is normally regarded as interfering background noise. This test method is based upon the work of Hubner , and Diehl, but differs from all other current sound power measurement procedures by requiring simultaneous measurement at both conformal surfaces and by resolving time-averaged sound pressure levels at both surfaces to within 0.1 dB. These two features, simultaneous recording and 0.1dB resolution, enable source sound power to be calculated when the direct sound field of the source is actually lower in level than the ambient noise.
The use of this test method is expected to be primarily for the relative assessment of the sound power from similar sources or for the prediction of sound levels in a plant based upon measurements of similar sources in another plant. This test method is believed to be capable of yielding a reasonably good estimate of absolute power level with proper care of application and full conformance to the provisions of this procedure.
The two-surface method is applicable only when the two measurement surfaces can be physically selected to produce positive values of the difference in average sound pressure level. That is, the inner surface sound pressure level minus the outer surface sound pressure level must be at least +0.1 dB. This limitation applies to each frequency band and each constituent surface area investigated. Only the frequency band in which a zero or negative difference occurs is it considered invalid and usually adjacent bands will be valid. In practice, only rar...
SCOPE
1.1 This test method covers the field, or  in situ measurement of sound power level by the two-surface method. The test method is designed to minimize the effects of reverberant conditions, directivity of the noise source under consideration, and the effects of ambient noise from other nearby equipment operating at the same time.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The insertion loss of a pipe lagging system depends upon the lagging system materials, the method used to apply the materials, the pipe wall thickness, the size and shape of the bare and lagged pipe, and the mechanisms causing noise radiation from the pipe. Insertion losses measured using this test method should be used with some caution. In the laboratory, measurements must be made under reproducible conditions, but in practical usage in the field, the conditions that determine the effective insertion loss are difficult to predict and they may lead to slightly different results. Insertion losses measured with this test method can be used successfully for acoustical design purposes. Insertion losses measured with this test method are most useful for pipes and lagging systems which are similar to those used in the laboratory configuration.
This test method may be used to rank-order pipe lagging systems according to insertion loss or to estimate the field insertion loss of pipe lagging systems installed in the field.
This test method assumes that pipe wall stresses resulting from different methods of supporting the test pipe in the laboratory do not have a significant effect upon the measured insertion loss.
Pipe lagging systems typically have small insertion loss, and sometimes negative insertion loss, at frequencies below 500 Hz. The results obtained at frequencies below 500 Hz may be somewhat erratic. Sound sources used with this test method normally have a low frequency limit in the range from 300 to 500 Hz. For these reasons, the lowest band of frequencies for which results are required is centered at 500 Hz.
SCOPE
1.1 This test method covers the measurement of the insertion loss of pipe lagging systems under laboratory conditions.
1.2 A procedure for accrediting a laboratory for purposes of this test method is given in Annex A1.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
Specimens tested using this standard, for example, duct silencers, are used to control sound propagation through ventilation ducts. The results gathered from testing specimens to this standard can be used to estimate the reduction in fan sound levels in ducted airflow systems caused by including a sound attenuating device in the system. The device can be a component in a source-path-receiver analysis where calculations are performed to determine the resultant sound level in an occupied space. Proper selection of a sound attenuating device can enable a designer to achieve in-space background noise criteria.
The insertion loss of a silencer is a matter of degree, and varies with frequency and with the direction and speed of airflow. Because silencers partially obstruct the air path and provide resistance to airflow, two other effects must be quantified: pressure drop and airflow-generated noise. Both increase with increasing air speeds; thus data are required for several airflows to correctly characterize performance.
The aerodynamic results from testing specimens to the standard can be used as information for the system design engineer to determine the amount of static pressure drop resistance to be overcome by the system fan(s). Guidelines for appropriate maximum allowable pressure drop for a sound attenuating element have been established in the design community and are based on the procedures described herein.
As stated previously in 1.5 of this test method, the actual performance of a sound attenuating device as installed in an air duct system may be significantly different than reported based on the test procedure herein. This standard does not provide guidance to the user on these system effects.
Silencers are often designed to be used under conditions which do not duplicate the test set-ups of this standard. Mock-ups and specialized test set-ups to determine performance of sound attenuating devices in non-standard configurations may be based on this t...
SCOPE
1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen field conditions.

SIGNIFICANCE AND USE
This is an in situ method, that is, the measurements are made at the actual installation. The sound levels measured according to this test method should be representative for that installation and for the quantity of acoustical absorption actually, permanently present.  
The test method has the following limitations:  
5.2.1 The test method produces sound data which may be compared with applicable criteria or limits only if they are in terms of the quantities measured in this test method.  
5.2.2 The test method does not quantify certain subjective aspects of the sound environment that may be objectionable. These include pure tones, spectral content, and temporal distribution.
SCOPE
1.1 This test method provides guidance to the methodology used in the measurement of building interior sound levels.
1.2 This test method describes procedures for measuring sound in enclosed residential spaces produced by built-in utilities and major appliances such as plumbing, heating, ventilating, air-conditioning systems, refrigerators, and dish washers. The measured values may then be used to assess compliance, design, or habitation suitability.
1.3 This test method does not promulgate or recommend acoustical criteria.
1.4 This test method is not intended for obtaining data to evaluate indoor environments for:
1.4.1 Commercial activities such as studios, communication centers, hospitals, and auditoria, and
1.4.2 Effects from exterior sources such as aircraft, railroad operations, motor vehicles, mining operation, weapons fire, etc.
1.5 This test method is not intended for evaluating sound transmission loss, sound absorption coefficient, or any other acoustical aspects of the space or structure.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This test method covers the laboratory testing of some of the acoustical properties of sound attenuating devices including duct liner materials, integral ducts, and in-duct absorptive straight and elbow silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 This method tests the performance of the specimen in well-defined and controlled conditions. If the specimen is installed in the field in any different manner, the results may be different. This standard does not provide estimating procedures for determining the actual installed performance of the specimen field conditions.

SCOPE
1.1 This guide is intended to provide a simple and consistent procedure for the in-situ field measurement of in-duct sound pressure levels in large low pressure industrial air ducts, such as for gas turbines or fans, where considerations such as flow velocity, turbulence or temperature prevent the insertion of sound pressure sensors directly into the flow. This standard guide is intended for both ambient temperature intake air and hot exhaust gas flow in ducts having cross sections of four (4) square meters, or more.
1.2 The described procedure is intended to provide a repeatable and reproducible measure of the in-duct dynamic pressure level at the inlet or exhaust of the gas turbine, or fan. The guide is not intended to quantify the "true" sound pressure level or sound power level. Silencers, as well as Waste Heat Boilers, must be designed using the in-duct sound power level as the basis. Developing the true sound power level based on in-duct measurements of true sound pressure within a complete operating system is complex and procedures are developmental and often proprietary.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Extreme caution is mandatory when working near hot exhaust gas systems and appropriate safety precautions such as the installation of quick acting isolation valves are recommended.

SCOPE
1.1 This test method covers the laboratory measurement of both the acoustical and mechanical performance of pneumatic exhaust silencers designed for quieting compressed gas (usually air) exhausts from orifices connected to pipe sizes up to 3/4in. NPT. This test method is not applicable for exhausts performing useful work, such as part conveying, ejection, or cleaning. This test method evaluates acoustical performance using A-weighted sound level measurements.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.

SCOPE
1.1 This test method covers the field, or  in situ measurement of sound power level by the two-surface method. The test method is designed to minimize the effects of reverberant conditions, directivity of the noise source under consideration, and the effects of ambient noise from other nearby equipment operating at the same time.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
This standard defines measurement procedures for estimating the risk of noise-induced hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and mobile, transportable, and stationary equipment. The primary approach is to separately measure the sound level at operator ear locations for each normal operating condition. These levels can be combined with operational use scenarios and exposure criteria to define noise exposure severity. The data can also be used to define hearing protection requirements or administrative controls to preclude hearing hazard.
The practice has the following limitations:
The practice uses field portable measurement equipment.
The practice produces data which may be compared with applicable criteria or limits if the limits are in terms of the quantities measured in this standard or which can be calculated from the measured data.
SCOPE
1.1 This standard defines noise measurement procedures for estimating the risk of hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and other mobile, transportable, or stationary equipment.
1.2 This standard does not recommend noise exposure limit levels or criteria for any application discussed.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
This standard defines measurement procedures for estimating the risk of noise-induced hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and mobile, transportable, and stationary equipment. The primary approach is to separately measure the sound level at operator ear locations for each normal operating condition. These levels can be combined with operational use scenarios and exposure criteria to define noise exposure severity. The data can also be used to define hearing protection requirements or administrative controls to preclude hearing hazard.
The practice has the following limitations:
5.2.1 The practice uses field portable measurement equipment.
5.2.2 The practice produces data which may be compared with applicable criteria or limits if the limits are in terms of the quantities measured in this standard or which can be calculated from the measured data.
SCOPE
1.1 This standard defines noise measurement procedures for estimating the risk of hearing loss among users of noise producing equipment. It is applicable to ground vehicles, aircraft, watercraft, and other mobile, transportable, or stationary equipment.
1.2 This standard does not recommend noise exposure limit levels or criteria for any application discussed.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This test method covers the laboratory testing of duct liner materials, integral ducts, and in-duct absorptive silencers used in the ventilation systems of buildings. Procedures are described for the measurement of acoustical insertion loss, airflow generated noise, and pressure drop as a function of airflow.  
1.2 Excluded from the scope are reactive mufflers and those designed for uses other than in ventilation systems, such as automobile mufflers.  
1.3 This test method includes a provision for a simulated semi-reflective plenum to fit around thin-walled duct and silencer test specimens, since the acoustical environments around such thin-walled specimens can affect the measured insertion loss.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This test method provides guidance to the methodology used in the measurement of building interior sound levels.
1.2 This test method describes procedures for measuring sound in enclosed residential spaces produced by built-in utilities and major appliances such as plumbing, heating, ventilating, air-conditioning systems, refrigerators, and dish washers. The measured values may then be used to assess compliance, design, or habitation suitability.
1.3 This test method does not promulgate or recommend acoustical criteria.
1.4 This test method is not intended for obtaining data to evaluate indoor environments for:
1.4.1 Commercial activities such as studios, communication centers, hospitals, and auditoria, and
1.4.2 Effects from exterior sources such as aircraft, railroad operations, motor vehicles, mining operation, weapons fire, etc.
1.5 This test method is not intended for evaluating sound transmission loss, sound absorption coefficient, or any other acoustical aspects of the space or structure.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This test method covers the field, or  in situ measurement of sound power level by the two-surface method. The test method is designed to minimize the effects of reverberant conditions, directivity of the noise source under consideration, and the effects of ambient noise from other nearby equipment operating at the same time.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SCOPE
1.1 This test method covers the measurement of the insertion loss of pipe lagging systems under laboratory conditions.
1.2 A procedure for accrediting a laboratory for purposes of this test method is given in Annex A1.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

SIGNIFICANCE AND USE
The insertion loss of a pipe lagging system depends upon the lagging system materials, the method used to apply the materials, the pipe wall thickness, the size and shape of the bare and lagged pipe, and the mechanisms causing noise radiation from the pipe. Insertion losses measured using this test method should be used with some caution. In the laboratory, measurements must be made under reproducible conditions, but in practical usage in the field, the conditions that determine the effective insertion loss are difficult to predict and they may lead to slightly different results. Insertion losses measured with this test method can be used successfully for acoustical design purposes. Insertion losses measured with this test method are most useful for pipes and lagging systems which are similar to those used in the laboratory configuration.
This test method may be used to rank-order pipe lagging systems according to insertion loss or to estimate the field insertion loss of pipe lagging systems installed in the field.
This test method assumes that pipe wall stresses resulting from different methods of supporting the test pipe in the laboratory do not have a significant effect upon the measured insertion loss.
Pipe lagging systems typically have small insertion loss, and sometimes negative insertion loss, at frequencies below 500 Hz. The results obtained at frequencies below 500 Hz may be somewhat erratic. Sound sources used with this test method normally have a low frequency limit in the range from 300 to 500 Hz. For these reasons, the lowest band of frequencies for which results are required is centered at 500 Hz.
SCOPE
1.1 This test method covers the measurement of the insertion loss of pipe lagging systems under laboratory conditions.
1.2 A procedure for accrediting a laboratory for purposes of this test method is given in Annex A1.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.