Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 10534 (1983): Method of Measurement of Airborne NoiseEmitted by Gas Turbine Installations [ETD 15: RotatingMachinery]

IS :10534-1983

Indian Standard

[

L.,I

METHOD OF MEASUREMENT OF AIRBORNENOISE EMITTED BY GAS TURBINE

INSTALLATIONS

Acoustics Sectional Committee, LTDC 5

Chairman

DR M. PANCHOLYEmeritus Scientist

National Physical Laboratory ( CSIR )New Delhi

Members Represent ing

SERI SAN~WZP AHUJA Ahuja Radios, New DelhiSBItIK. R. GUXUMURTHY (Alternate)

COL T. R. BH~LOTttA Ministry of Defence ( DGI )LT-COL KIS HAN LAL ( Alternate)

SERI K. CHAFJDRAI:HUDAN Directorate General of Civil Aviation, New DelhiSHSZIM. P. SANrA( Alternate)

DR A. F. CHH.APGAR Nati~e:~iPhysical Laboratory ( CSIR ), New

SsiRI V. V. GHATE Peico Electronics & Eiectricals Ltd, Bombay; andThe Radio Electronics & Television Manu-facturers’ Association, Bombay

SHRI K. D’s~ ( Alternate) The Radio Electronic & Television Manu-facturers’ .Association, Bombay

DR P. N. GUPT.A Department of Electronics, New DelhiSHRI ‘rEK GHANDANI ( Alternate)

SHRI K. S. KALIDAS ‘ ‘ Railway Board, Ministry of RailwaysSH~I V. JAYASiAMAN ( Alternate )

SHRI J. S. MONGA Bolton Industrial Corporation, New DelhiSHRI M. S. MONQA ( Alternate )

SHRI B. C. MUKHERJEE National Test House, CalcuttaS HRI J. K. BHATTACHARYA ( Alternate )

DR ( KWMARI ) SHAILAJA NIKAM All India Institute of Speech & Hearing, MysoreSHRI K. D. PAVATE Central Electronics Engineering Research Institute

( CSIR ), PilaniSHRI M. R. KAPOOR ( Alternate)

SER1 A. V, RAMANAN Films Division, Bombay Directorate General ofDR C. S. R. RACI All India Radio, New Delhi

( Confinued on page 2 )

(Q Copyright 1983INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Copyright Act ( XIV of 1957) andreproduction in whole or in part by any means except with written permission of thepublisher shall be deemed to be an infringement of copyright under the said Act.

——. — ..— ——

I

IS :10534-1983

( Ccmtinued@rn page 1 )

Members Representing

SHRI M. SANKAEALINGAm Directorate General of Supplies & Disposals( Inspection Wing), New Delhi

SHRI R. S. ARORA ( Alternate)SHRI M. N. SEVKLA Posts & Telegraphs Board, New Delhi

SHRI S. K. TANDON ( Alternate)CDR P. K. SINEA Ministry of Defence ( R & D )

LT R. S. DUTTA ( Alternate)STJPERIN~ENDTNCISURVEYOR OF Central Public Works Department, New Delhi

WORKS ( FOOD)SHRI R. C. JAIN, Director General, 1S1 ( Ex-ojicio Membw )

Head ( Electronics)

Secretory

SER~ PAVAN KUMARAssistant Director ( Electronics), 1S1

2

. ..—

IS :10534-1983

Indian StandardMETHOD OF MEASUREMENT OF AIRBORNE

NOISE EMITTED BY GAS TURBINEINSTALLATIONS

O. FOREWORD

0.1 This Indian Standard was adopted by the Indian StandardsInstitution on 28 December 1982, after the draft finalized by the AcousticsSectional Committee had been approved by the Electronics andTelecommunication Division Council.

0.2 Recommendations on the specification of sound pressure levelsaround installation are also given in Appendix A.

0.3 While preparing this standard , assistance has been derived fromISO/DIS 6190 Acoustics — Measurement of airborne noise emitted bygas turbine installations — Specifications and survey method, issued bythe International organization for Standardizations ( 1S0 ).

0.4 In reporting the result of a test made in accordance with thisstandard, if the final value, observed or calculated, is to be round off, itshall be done in accordance with 1S : 2-1960*.

1. SCOPE

1.1 This standard specifies a survey method for measuring external soundpressure levels emitted around a complete gas turbine installation.

2. TERMINOLOGY

2.1 For the purpose of this standard, the definitions at 2.1.1 to 2.1.5besides those given in IS :1885 ( Part III )T, shall apply.

2.1.1 Sound Pressure Level, Lp, in Decibels — Ten times the logarithm tothe base 10 of the ratio of the mean-square sound pressure of a sound tothe square of the reference sound pressure. The frequency weightingnetwork or the width of the frequency band used shall be indicated

*Rules for rounding off numerical values ( revised).tElectrotechnical vocabulary : Part III Acoustics.

3

-—,

IS :10534-1983

together with the quantity, for example, CA-weighted sound pressure level’and ‘octaveband sound pressure level’. The reference sound pressureis 20 WPa.

2.1.2 Weighting Networks and Octaue Filters — The A- and C-weightingnetworks shall be in accordance with IS : 9779-1981*.

2.1.3 Equivalent Sound Pressure Leuel, L,q in Decibles — The mean-squaresound pressure level during the measurement period. It is calculated asfollows:

T

Jp’(t) dt.& = lolg+- —Po’

0

where

p (t) = instantaneous sound pressure;

PO= reference sound pressure, 20 NPa; and

T = observation time in seconds.

2.1.4 Background Noise — The sound pressure level at the microphonepositions which is not generated by the installation under test.

2.1.5 Maximum Plant Dimension, 1 — Maximum dimension, measuredeither horizontally or vertically, between the farthest points of thecomplete installation ( see A-1 and A-3).

3. FIELD OF APPLICATION

3.1 This method is applicable to land based stationary installationspowered by gas turbines in single or multiple arrangements.

3.1.1 The method may be applied, but not limited, to gas turbinedriving generators, compressors or pumps, in simple or compound cycleor waste heat recovery systems, The method is not applicable when themechanical power output from the gas turbine( s ) is only a small part ofthe total installation output.

3.2 Gas turbine used for propulsion of vehicles are excluded from thisstandard.

3.3 This standard may be used a? a guide when specifying soundpressure levels from the gas turbine and its associated equipment, asdefined in 3.1.

*Specification for sound level meters.

IS :10534-1983

4. ACOUSTIC ENVIRONMENT

4.1 General — Numerous environmental factors affect the soundmeasured at a specified orientation and distance relative to a gas turbineinstallation. These include atmospheric conditions, surroundingtopography and background noise.

4.2 Atmospheric Conditions — Measurements should not be madeduring periods of rain or snow or when the average wind velocity,measured 1.5 m above the ground, exceeds 3 m/s ( exceptionally, a windvelocity up to 5 m/s may be accepted a“nd mentioned in the test report ).Abnormal conditions of temperature and humidity at the site should beavoided. Cloudy or night-time conditions are preferred to minimizeunusual effects due to temperature gradients.

4.3 Background Noise — At the microphone positions, the soundpressure level ( weighted and in each octave band ) of the backgroundnoise shall be at least 3 dB, and preferably more than 10 dB below thesound pressure level with the source operating.

4.3.1 This margin may be attained by changing the time when themeasurements are made or by changing the measurement positionswithin the limits specified in 7.2. If this is not possible, the resultsdetermined with a higher background noise shall be corrected as specifiedin 8.2.

5. INSTRUMENTATION

5.1 Sound Level Meter — A sound level meter that meets therequirements of IS : 9779-1981* shall be used with the ‘slow’ metercharacteristic, with A- and C- frequency weighings.

NOTI+— The ‘Fast’ matter characteristic may he used to check that interferingevents are not influencing the measurements.

5.2 Octave-Band Filter Set — The octave-band filter set shall meetthe requirements of IS :6964- 1973~. The centre frequencies of thefrequency bands shall correspond to those of IS :2264-1963$, from 31.5 Hzto 8000 HZ.

5.3 Other Instrumentation — When instrumentation other than asound level meter is used, its calibration shall show that the accuracy ofthe results will not be inferior to that requirements of IS : 9779-1981*.

——*Specification for sound level meters.TSpecification for octave, half-octave and third-octave hand filters for analysis of

sound and vibrations.$Preferred frequencies for acoustical measurements.

5

IS :10534-1983

5.4 Calibration — At least before and after each series of measurements,an acoustical calibrator with an accuracy of -& 0-5 dB shall be applied tothe microphone for calibration of the entire measuring system, includingcable and tape recorder, if used, at one or more frequencies.

5.4.1 One of these frequencies shall be in the range 250 to 1000 Hz.If there is a calibration level change exceeding 1“O dB, the test series shallbe repeated.

5.4.2 The calibrator shall be checked annually to verify that its outputhas not changed. In addition; to ensure that the requirements ofIS :9779-198 I* and IS :6964-19737 are met, the measuring equipmentshould be calibrated over its entire frequency range annually.

5.5 Windscreen — A microphone windscreen shall be used whenmaking measurements outdoors. Its effect on the frequency response ofthe sound level meter shall not exceed -J 0“5 dB at frequencies below2000 Hz, and + 1 dB at frequencies ii-em 2000 to 10000 Hz.

6. GAS TURBINE OPERATION

6.1 The gas turbine plant shall include all construction features describedin the purchase agreement, regardless of whether they are essential or notfor the operation of the plant. All gas turbines and equipment requiredfor normal operation of the machine, throughout the range of operatingconditions, shall be running at steady-state conditions and at the specifiedrated load, as ~equired by the purchaser’s specification. “remporarynoise sources ( such as, starting device, compressor starting bleed airflowand steam blow ) shall be measured separately if required by thepurchaser’s specification.

6.2 All enclosure doors and access panels shall be closed.

7. MEASUREMENT OF SOUND PRESSURE LEVEL

7.1 Microphone Position – The microphone shall be located between1-4 m and 1‘6 m above ground level, and, if practical, at least 3-5 mfrom walls, building or other sound reflecting structures.

7.2 Number and Distance of Measuring Positions

7.2.1 The measuring positions shall be located at the specified distancefrom the installation, and preferably with one point on the main axis ofthe installation.

*Specification for sound level meters.‘~Specification for octave, half-octave and third-octave band filters for analysis of

sound and vibrations.

6

——7

IS: 10534-1983

7.2.2 The minimum number ofmeasuring positions shall be eight, thepoints being approximately equally spaced.

7.2.3 The positions may be moved depending on local conditions( background noise, accessibility; reflecting surfaces, screens andtopographical conditions ) as defined in A-5. If the distance has to bechanged, it must be as close as possible to the specified distance, andin all cases shall be not greater than 200 m, not less than the majorinstallation dimension and not less than 50 m.

\ 7.2.4 The installation shall be visible from the measurement positions.

I7.3 Setting of the Sound Level Meter

1

[ 7.3.1 The ‘Slow’ meter characteristic shall be used.

7.3.2 The A-weighted sound pressure level is always measured.

7.3,3 The C-weighted and the 9 octave-band sound pressure levels aremeasured if required by the purchaser’s specification.

7.4 Temporal Characteristics of the Sound

7.4.1 If the reading of the sound level meter varies over a range lessthan 6 dB, using the ‘slow’ meter characteristic, during the period ofobservation, the noise is considered to be steady for the purposes ofthis standard, and the level is taken to be the average of the maximumand minimum levels during the period of observation.

7.4.2 When the sound level varies over a range greater than 6 dB, thenoise is considered to non-steady and the levels to be noted are themaximum and minimum levels during the period of observation. In sucha case, the determination of L.q may be required. The period ofobservation shall be long enough to give a representative indication of the

! range of fluctuation of the noise.

I

7.5 Background Noise — The background noise shall be measured ateach microphone position, using the A- and C-weighting networks or eachoctave band as required, before and, if possible, after the gas turbinemeasurements.

7.5.1 If the background noise is unsteady, its level shall be determinedas described in 7.4.

.

8. CALCULATION OF MEAN SOUND PRESSURE LEVELS

8.1 Data Correction for Instrumentation — The first correction to beapplied shall be for the instrumentation. This includes any factors forcalibration, windscreen, microphone cable, etc.

7

..I

1S :10534-1983

8.2 Data Correction for Background Noise — The sound pressurelevels recorded at each of the microphone positions shall be corrected forthe influence of the background noise in accordance with the following:

DzYerence Between Sound pressure Correction to be Subtracted fromLevel Measured with Gas Turbine Sound Pressure Level MeasuredOperating and Background Sound with Gas Turbine Operating to

Pressure Lcvei Alone Obtain Sound Pressure Level dueto Gas Turbine Alone

cl13 d13

3 3

4 2

.5 2

6 1

a 1

8 1

9 1

> 10 0

If the sound pressure level increases by 3 to 5 clB with the gas turbineoperating, the correction shall be applied and the results given inbrackets.

8.3 Data Correction for Distance — When a measuring position isnot at the specified distance d, a correction may be applied, after anycorrection for background noise, using the following formula:

Lp(d)=Lp(d, )– 20 Ig $

where

dl = measuring distance; and

LP ( dl ) = sound pressure level measured atcorrected for background noise.

8.3.1 This formula

a) assumes a hemispherical propagation;

distance dl and

b) ignores the effect of atmospheric absorption; and

c) is not applicable when dl is less then 1-5 1 where 1 is the maximaldimension of the installation.

8

IS :10534-1983

8.3.2 Inthiscase also, theresults shall begiven in brackets.

8.3.3 This procedure must be allowed by the purchaser’s specification.

8.4 Data Averaging — The sound pressure level of the installation shallbe taken as the average LP, of the measured and corrected levels at thepositions around the installation.

8.4.1 Where the range of levels is 5 dB or less, the average shall betaken as the arithmetic mean of the levels measured.

8.4.2 Where the range of levels is 6 dB or more, the average soundpressure level shall be the level of the mean-square sound pressureobtained by the following formula:

r N 1Lp = 10 Ig -~– ~ 10°”l Lpi 1

where

Lpi =

.N=

L ~=1 J

freqency-weighted or octave-band sound pressurelevels expressed in decibels, at position ~ and

total number of measurement positions.

9. COMPARISON OF MEASURED AND SPECIFIED SOUNDPRESSURE LEVELS

9.1 The noise specification will be satisfied if the value of the averagesound pressure level Lp is not greater than the specified level.

10. MEASUREMENT UNCERTAINTY

10.1 There is an uncertainty inherent in the measurements due tovariations in meteorological conditions and to tolerances in the instru-me ntation. The tolerances given below include these factors and may beused when comparing the measured and specified sound pressure levelsat individual measurement positions:

Tolerance on SoundPressure Level

dB

Frequency weighted level:

“A 3

c 5

9

I

IS :10534-1983

Octave band level centre frequency:

31”5 to 125 Hz 5

250 Hz 4

500 to 8000 Hz 3

11. INFORMATION TO BE REPORTED

11.0 The following details shall be included in the test report.

11.1 Gas Turbine Plant Under Test

a)

b)

c)

d)

e)

f)

g)

h)

j)

Purchaser or user.

Location.

Number of gas turbine, their model and manufacturer.

Air intake temperature at atmospheric pressure.

Load and shaft rotational speed at the time of noise measure-ments.

Date and time of measurements.

Description of gas turbine, driven equipment, auxiliary equipmentand sound control treatment.

Plant sketch with a scale and dimensions showing main items ofplant, stack height, topographical and physical features andmeasurement positions ( see Fig. 1).

List of all equipment of significant noise, in operation duringmeasurements.

11.2 Acoustic Environment

a)

b)

c)

Description of the test environment ( include a dimensionedsketch with a scale showing the location of source with respect tosurrounding terrain, including a physical description of the testenvironment, with position of significant buildings, structures orother reflecting objects, description of the ground surfacesurrounding the installation and proximity of other significantnoise sources ).

Meteorological conditions at 1”5 m above ground, includingtemperature, relative humidity, wind speed and wind direction.

Reasons for moving the measuring positions from the specifieddistance.

10

IS :10534-1983

PACKAGE POWER PLANT 3

{SINGLE UNIT)2 4

d

o e 05AIR lNLE; ~

8>, (

6

CHIMNEY7

MULTIPLE

GAS TURBINE IN BUILDING 7WITH SEPARATE 6AIR INLET ANDOUTDOOR HEATRECOVERY BOILER

CHIMNEY

50

0 MICROPHONE POSITIONS4 d SPECIFIED DISTANCE

o3

(PREFERABLY 100m)

FIG, 1 MICROPHONE POSITIONS

11

IS :10534-1983

11.3 Instrumentation

a) Name, manufacturer, model number, grade of precision andserial number of all equipment used.

b) Method used to calibrate the instrumentation system.

c) Date and place of calibration of the acoustical calibrator.

d) Name of the personnel who performed and observed themeasurements.

11.4 Acoustical Data

a)

b)

c)

d)

e)

The frequency-weighted or octave-band sound pressure levels atall microphone positions. ( All measured sound pressure levelsare reported to the nearest decibel.)

The corresponding levels of the background noise and thecorresponding corrections, if any.

Corrected sound pressure levels at the specified distance.

If required, average sound pressure level, Lp, as determined in8.4.

Remarks on subjective impression of noise, with particularreference to time variations of noise level, audible discrete tones,spectral content, meteorological conditions, etc.

APPENDIX A

( C/ause 0.2 )

RECOMMENDATIONS ON NOISE SPECIFICATIONS

A-1. INSTALLATION

A-1.l The purchaser’s specification must clearly define the installationfor which the noise specification is applicable, including the buildingenclosing the several kinds of equipment associated with the gas turbine.

A-1.l.l This equipment may include:

- fired or unfired boilers,

— chimneys,

— steam turbines,

I

II

1

12

1S: 10534-1983

\

. cooling towers,

— fans,

— turbo-generators,

— transformers,

— compressors, etc.

I A-1 .1.2 Temporary noise sources and equipment not associated withthe cas turbine are excluded from this standard unless the purchaser’s.,,specdication specifically includes them.

A-1.1.3 The number of gas turbine units in operation simultaneously,for which the noise specification is applicable, shall be stated.

A-2. QUANTITY TO BE MEASURED

A-2.1 Gas turbine installation environmental noise is specified by threeprocedures as follows : /

a) Mandatory, in A-weighted sound pressure levels,

b) Optionally, in C-weighted sounded pressure level, and

c) Optionally, in 9 octave-bands with centre frequencies from31-5 to 8000 Hz.

A-3. SPECIFIED DISTANCE

A-3.1 A specified distance d ( see Fig. 1 ) shall be selected and its valuestated in the noise specification. This distance d is the distance betweenthe microphone position and the nearest point on the perimetersurrounding the noise source as would be determined by stretching astring around the installation. The value chosen for d is preferably 100 m,but it may be increased to 200 m for large installations, depending onthe maximal dimension 1 of the installation ( including chimney height ).Values of d for different values of 1 are as follows:

d = 100 m for 1<50 m ( preferred distance )

d=150mfor 50m<l<100m

d==200mfor100m<l

A-3.1.1 The expected values of background noise may well influencethe value chosen for d ( see 4.2 and 8.3 ).

13

IS :10534-1983

A-4. SPECIFICATION LEVEL

A-4.1 The purchaser’s specification may place limits either on themaximum level at one or more of the measurement positions or on themean value determined from measurements at all the prescribedpositions.

A-5. TEST ENVIRONMENT

A-5.1 The purchaser’s specification shall state whether or not the terrainis relatively flat and shall mention any large reflecting surfaces( buildings, cooling towers, etc ), with a surface greater than 10 mz,which are within ( d + 50 ) m of the source.

A-5.1.1 These factors may influence the acoustic design for theinstallation and the measurement results. In the absence of such a state-ment the terrain is assumed to be a flat reflecting surface, without othersignificant reflecting surfaces.

14